CN112176147B - Manufacturing method of normalized thick steel plate suitable for large-wire welding - Google Patents
Manufacturing method of normalized thick steel plate suitable for large-wire welding Download PDFInfo
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- CN112176147B CN112176147B CN202011092893.9A CN202011092893A CN112176147B CN 112176147 B CN112176147 B CN 112176147B CN 202011092893 A CN202011092893 A CN 202011092893A CN 112176147 B CN112176147 B CN 112176147B
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 161
- 239000010959 steel Substances 0.000 title claims abstract description 161
- 238000003466 welding Methods 0.000 title claims abstract description 43
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 24
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims abstract description 38
- 238000005096 rolling process Methods 0.000 claims abstract description 24
- 238000005266 casting Methods 0.000 claims abstract description 20
- 229910052786 argon Inorganic materials 0.000 claims abstract description 19
- 238000001816 cooling Methods 0.000 claims abstract description 19
- 238000003756 stirring Methods 0.000 claims abstract description 14
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910000882 Ca alloy Inorganic materials 0.000 claims abstract description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 11
- 229910000636 Ce alloy Inorganic materials 0.000 claims abstract description 7
- 239000002994 raw material Substances 0.000 claims abstract description 3
- 230000001276 controlling effect Effects 0.000 claims description 46
- 238000000034 method Methods 0.000 claims description 38
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 26
- 229910052757 nitrogen Inorganic materials 0.000 claims description 25
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 24
- 229910045601 alloy Inorganic materials 0.000 claims description 23
- 239000000956 alloy Substances 0.000 claims description 23
- 230000008569 process Effects 0.000 claims description 23
- 229910052748 manganese Inorganic materials 0.000 claims description 21
- 229910052710 silicon Inorganic materials 0.000 claims description 18
- 229910052720 vanadium Inorganic materials 0.000 claims description 16
- 238000003723 Smelting Methods 0.000 claims description 14
- 239000000203 mixture Substances 0.000 claims description 14
- 239000002893 slag Substances 0.000 claims description 13
- 229910052698 phosphorus Inorganic materials 0.000 claims description 12
- 238000007664 blowing Methods 0.000 claims description 11
- 239000007789 gas Substances 0.000 claims description 11
- 229910052719 titanium Inorganic materials 0.000 claims description 10
- 229910052796 boron Inorganic materials 0.000 claims description 8
- 229910052758 niobium Inorganic materials 0.000 claims description 8
- 229910052717 sulfur Inorganic materials 0.000 claims description 8
- 229910052804 chromium Inorganic materials 0.000 claims description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims description 6
- 229910052759 nickel Inorganic materials 0.000 claims description 6
- 238000009489 vacuum treatment Methods 0.000 claims description 6
- 229910052802 copper Inorganic materials 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 5
- 238000004321 preservation Methods 0.000 claims description 4
- 238000005098 hot rolling Methods 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 3
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims description 3
- 238000005507 spraying Methods 0.000 claims description 3
- 238000009849 vacuum degassing Methods 0.000 claims description 3
- 230000001105 regulatory effect Effects 0.000 claims description 2
- 229910000859 α-Fe Inorganic materials 0.000 abstract description 4
- 239000010936 titanium Substances 0.000 description 34
- 239000011575 calcium Substances 0.000 description 29
- 229910052799 carbon Inorganic materials 0.000 description 21
- 239000011572 manganese Substances 0.000 description 20
- 238000009847 ladle furnace Methods 0.000 description 18
- 239000000047 product Substances 0.000 description 18
- 239000012071 phase Substances 0.000 description 16
- 229910001566 austenite Inorganic materials 0.000 description 15
- 229910052742 iron Inorganic materials 0.000 description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 11
- 229910052791 calcium Inorganic materials 0.000 description 11
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 9
- 239000002131 composite material Substances 0.000 description 8
- 238000007689 inspection Methods 0.000 description 8
- 229910052684 Cerium Inorganic materials 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- 230000009466 transformation Effects 0.000 description 7
- 229910052782 aluminium Inorganic materials 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000005728 strengthening Methods 0.000 description 6
- 230000001914 calming effect Effects 0.000 description 5
- 230000002401 inhibitory effect Effects 0.000 description 5
- 238000001556 precipitation Methods 0.000 description 5
- 230000009467 reduction Effects 0.000 description 5
- 238000010079 rubber tapping Methods 0.000 description 5
- 238000007711 solidification Methods 0.000 description 5
- 230000008023 solidification Effects 0.000 description 5
- 239000005997 Calcium carbide Substances 0.000 description 4
- 238000005275 alloying Methods 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 238000010606 normalization Methods 0.000 description 4
- 238000007781 pre-processing Methods 0.000 description 4
- 238000003303 reheating Methods 0.000 description 4
- CLZWAWBPWVRRGI-UHFFFAOYSA-N tert-butyl 2-[2-[2-[2-[bis[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]amino]-5-bromophenoxy]ethoxy]-4-methyl-n-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]anilino]acetate Chemical compound CC1=CC=C(N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(OCCOC=2C(=CC=C(Br)C=2)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)=C1 CLZWAWBPWVRRGI-UHFFFAOYSA-N 0.000 description 4
- 229910000851 Alloy steel Inorganic materials 0.000 description 3
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000011574 phosphorus Substances 0.000 description 3
- 230000002829 reductive effect Effects 0.000 description 3
- 238000007670 refining Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- 229910000742 Microalloyed steel Inorganic materials 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 229910001563 bainite Inorganic materials 0.000 description 2
- 239000010953 base metal Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000009749 continuous casting Methods 0.000 description 2
- 230000001627 detrimental effect Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 230000001939 inductive effect Effects 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 230000000670 limiting effect Effects 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 239000010955 niobium Substances 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- RMLPZKRPSQVRAB-UHFFFAOYSA-N tris(3-methylphenyl) phosphate Chemical compound CC1=CC=CC(OP(=O)(OC=2C=C(C)C=CC=2)OC=2C=C(C)C=CC=2)=C1 RMLPZKRPSQVRAB-UHFFFAOYSA-N 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- IUVCFHHAEHNCFT-INIZCTEOSA-N 2-[(1s)-1-[4-amino-3-(3-fluoro-4-propan-2-yloxyphenyl)pyrazolo[3,4-d]pyrimidin-1-yl]ethyl]-6-fluoro-3-(3-fluorophenyl)chromen-4-one Chemical compound C1=C(F)C(OC(C)C)=CC=C1C(C1=C(N)N=CN=C11)=NN1[C@@H](C)C1=C(C=2C=C(F)C=CC=2)C(=O)C2=CC(F)=CC=C2O1 IUVCFHHAEHNCFT-INIZCTEOSA-N 0.000 description 1
- 229910000744 A-2 tool steel Inorganic materials 0.000 description 1
- 229910000926 A-3 tool steel Inorganic materials 0.000 description 1
- 229910001087 A-4 tool steel Inorganic materials 0.000 description 1
- 229910001275 Niobium-titanium Inorganic materials 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- SKKMWRVAJNPLFY-UHFFFAOYSA-N azanylidynevanadium Chemical group [V]#N SKKMWRVAJNPLFY-UHFFFAOYSA-N 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000005422 blasting Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000001427 coherent effect Effects 0.000 description 1
- 239000007771 core particle Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- RJSRQTFBFAJJIL-UHFFFAOYSA-N niobium titanium Chemical compound [Ti].[Nb] RJSRQTFBFAJJIL-UHFFFAOYSA-N 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 150000004763 sulfides Chemical class 0.000 description 1
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical compound S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Treatment Of Steel In Its Molten State (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
A manufacturing method of a normalized thick steel plate suitable for large-line weldable and having a yield strength of not less than 380MPa comprises the following steps: the obtained molten steel is taken as a raw material, a Ca alloy wire and a Ce alloy wire are fed, then argon is blown weakly at the bottom of a tank for stirring, a casting blank is obtained by pouring, iron oxide scales on the surface of the casting blank are removed, a steel plate is obtained by rolling, and a normalized thick steel plate is obtained by water cooling and normalizing. After the produced casting blank is hot-rolled into a steel plate, the steel plate which has the yield strength of more than 380MPa and KV2 at-20 ℃ of more than 120J and takes ferrite as a main body structure can be obtained after normalizing, the obtained steel plate is welded under the condition of large linear energy with welding heat input of 400-500 KJ/cm, and KV2 at-20 ℃ in a HAZ zone of a welding seam can reach more than 80J.
Description
The technical field is as follows:
the invention relates to a method for manufacturing a normalized thick steel plate with yield strength not lower than 380MPa, which is suitable for large-line welding, and belongs to the field of low-alloy steel manufacturing.
Background art:
in order to ensure the impact toughness of the HAZ superheat zone of the steel plate under the condition of large linear energy welding, people generally take measures from three aspects, one is that the excessive hardening of the welding heat affected zone is inhibited as far as possible and the M-A phase is rarely generated by controlling the content of alloy elements and carbon equivalent; secondly, the influence of the segregation of impurity elements on the low-temperature toughness of the HAZ zone is reduced through high-cleanness control and organization and multi-interface of the HAZ zone; and thirdly, the steel matrix and the corresponding HAZ zone phase composition need to have good toughness.
For these reasons, the carbon content of steel sheets for large-diameter wire weldability is relatively low, and steel sheets produced by the TMCP process or the temper process are generally used to obtain high strength, but as the thickness increases, the uniformity of the structure in the thickness direction of steel sheets produced by these two processes deteriorates, the requirements on equipment conditions also become higher, and high-strength steel sheets for large-diameter wire weldability having a thickness of 60mm or more are difficult to produce. The normalizing process can ensure that the steel plate has the characteristics of uniform section structure and stable performance, and the degree of limitation of equipment conditions in the aspect of large thickness is smaller, so the steel plate is more favored when being used for producing thick steel plates. However, since the structure strengthening and the fine grain strengthening after the normalizing are greatly weakened, the solid solution strengthening compensation by adopting the carbon content and the alloy elements is contrary to the strategy of improving the toughness of the HAZ zone, so that how to produce the high-strength normalized steel plate suitable for large-line welding becomes a problem.
Aiming at the problem of toughness degradation of large-wire weldable HAZ, a method that dispersed and precipitated TiN particles and the like are not completely redissolved in the reheating process and residual nitrides reach critical-scale effective nail-rolling austenite grain boundaries is introduced to inhibit austenite coarsening.
Document 1 "publication No. CN 1962916A" is based on this assumption. This document employs a method of controlling the relation of the ratio of Ti to N, and intends to suppress coarsening of the reheated austenite by TiN fine particles remaining during reheating, thereby obtaining a fine transformation structure during the subsequent cooling process and securing the toughness of the HAZ region. The steel plate is designed to contain more than 0.020% of Nb, the nitrogen content range is 30-100 PPm, the V content is less than or equal to 0.06%, the ranges of other elements are wide, the influence of M-A on the performance of an HAZ region is not considered, and the steel plate is suitable for hot rolling.
In the document 2, "CN 104498827A" improves the performance of the base material by controlling the low carbon equivalent and the low P, S, so as to ensure that the HAZ zone also has good toughness, the toughness of the HAZ zone under the condition of large-line welding cannot be completely ensured, and the yield strength after normalizing cannot reach 355 MPa. Document 3 "CN 102459656A" is a document in which reheat austenite coarsening is suppressed by Ti nitrides, oxides and sulfides of Mg and Ca, and phase transformation core particles are induced by BN and VN as HAZ zones. It is not suitable for normalized high-strength steel which is compatible with large-line weldability, and is not industrially easy to realize because the contents of each element are strictly controlled to satisfy the corresponding restriction relationship. Document 4 "CN 106574316B" proposes improvement of toughness by controlled rolling with a low carbon equivalent content. The core is to guarantee the strength by controlling the cooling on the premise of low carbon equivalent. In the aspect of large-wire-energy welding adaptability, firstly, the formation of M-A is controlled by using low-C component and low-strength carbide forming elements, secondly, TiN is used for inhibiting the coarsening of HAZ reheat austenite, and thirdly, BN and oxysulfide are used as intragranular transformation induction cores to refine bainite in an HAZ superheat zone. The weight percentage of the calcium remained after the combination with oxygen is controlled to be 1.25 times lower than that of sulfur, which is the first characteristic of the method, the addition of Ti \ B and the control of N content are similar ideas of the document 1 and the document 3, and the addition of Zr, Mg, REM and the like are similar to the document 3. The preferable range of Ti is 0.01-0.035%, the preferable content of Al is 0.01-0.10%, the preferable range of B is 0.0008-0.0025%, N in the steel is preferentially combined with Ti and Al, so that the content of B is large enough to sharply increase the hardenability of the steel, namely, B is easy to deviate to a crystal boundary in the reheating process to block the diffusion of carbon, and when strong carbide forming elements such as Mo, V, Cr and Nb exist in the steel, side plate bainite or more MA phases appear after phase transformation, which may sharply damage the toughness of an HAZ zone. The content range of N is 0.003-0.010%, and the content range of V, Mo and Cr is wide, but in a normalized state, because the strength needs to be ensured, elements which are easy to form an M-A phase such as V, Mo and Cr need to be improved, the high strength and the excellent toughness of a large-wire weldable HAZ region are difficult to be considered at the same time. Document 5 "CN 103114241 a" proposes measures to control the ultra-low carbon content, add Ni and Cu, control low P, low S, and make higher N present in the steel, make Ti/N value 1-2, add B, and control Al to be 0.01% or less, with the intention of suppressing the growth of reheated austenite by forming TiN with high re-dissolution temperature. Because the content of nitrogen fixation elements is low and excessive N exists, the welded heat affected zone is easy to embrittle on the basis of insufficient nitrogen fixation elements, and the toughness stability of the heat affected zone under the condition of large-linear-energy welding cannot be completely guaranteed. To ensure that the yield strength after normalizing reaches above 355MPa, noble metals such as Cu, Ni and the like with higher content need to be added, and the economic value is insufficient.
Document 6 "CN 107287508A" is actually a low carbon microalloyed steel, the composition of which is very common, and the base metal can be made to have high impact toughness by adopting TMCP process, but the HAZ zone performance of large wire weldable is uncertain.
Document 7 "CN 106756543 a" is actually a low-carbon microalloyed steel, which substantially limits the carbon equivalent, reduces P \ S, and produces a steel sheet by a trace Ca treatment. Compared with the existing common high-performance steel, the method does not embody a substantive technology aiming at large-line welding, and in the component range, because the carbon equivalent is limited, the component control range of the normalized yield strength reaching above 355MPa is very narrow according to the design, so that the method is not suitable for industrial production of the high-strength normalized steel.
Document 8 "CN 106906413 a" also proposes a composition scheme intended to realize a nucleation core with dispersed fine oxides as the reheat austenite intracrystalline mass transfer induced synergistic phase transformation in the HAZ region by composition control. The composition design emphasizes that the S content is less than 0.007 percent but not less than 0.0015 percent, limits the range of Al, Ti, Mg, N and the like, and proposes that the Mg/Ti value is not less than 0.017, and the S content after subtracting one-to-one molar ratio of S to Ca, REM, Zr, Mg and the like is 0.0003 to 0.003 percent and the like. The yield strength after normalizing is difficult to stably reach more than 355 MPa.
Document 9 "CN 108677088A" proposes a composition scheme and a smelting and rolling scheme in which the contents of boron and nitrogen in steel are increased based on low-carbon low-silicon nickel-added manganese-containing steel, and after one-to-one boron with the nitrogen content as a molar ratio is subtracted, the remaining boron is 0.001% to 0.0020%. The proposal has more noble alloys (the minimum content is 0.80 percent), high cost and low economy, and the interval of components with the yield strength stably reaching above 355MPa after the normalization of the thick steel plate is narrow, thereby being difficult to realize the industrial production control.
Document 10 "CN 109097685 a" discloses a method for producing a large-wire weldable steel plate in which coarsening of weld reheating austenite is suppressed by TiN, which is characterized in that based on a low-phosphorus low-sulfur low-carbon manganese-containing low-alloy steel, AL deoxidation is performed, acid-soluble aluminum of 0.02% or more is retained, microtitanium treatment is performed, 0.0008 to 0.0015% of B element is added, 0.04 to 0.10% of V is added, and N is controlled to be 0.007 to 0.009% and not more than 0.003+0.28Ti +0.03V +1.27B, and a cast slab is heated and then rolled by three-stage controlled rolling to obtain the steel plate. A toughness measurement of the HAZ zone of the steel sheet after welding at a weld heat input of 100KJ/cm is given. The method is suitable for production in a controlled rolling and controlled cooling mode, N in the normalized steel is preferentially combined with Al, B, Ti and the like for precipitation, and VN strengthening effect is almost not achieved. Document 10 "CN 109161671 a" discloses a method for manufacturing steel for large-wire welding based on low-carbon niobium-titanium microalloyed low alloy steel, which is characterized in that a converter and a refining electric furnace are used for smelting steel with the final component range of C: 0.06% -0.18%, Si: 0.15 to 0.50 percent of steel, 1.10 to 1.60 percent of Mn, less than or equal to 0.012 percent of P, less than or equal to 0.003 percent of S, 0.10 to 0.40 percent of Ni, 0.010 to 0.030 percent of Nb, less than or equal to 0.010 percent of Al, 0.010 to 0.030 percent of Ti and 0.002 to 0.010 percent of Ca, wherein Al deoxidation is not adopted in refining after smelting in a converter, Al element is controlled to be less than or equal to 0.0075 percent, free oxygen in the steel is in the range of 10 to 100PPm, Ti is added for microalloying, small Ti oxides are formed in the steel, and calcium treatment is carried out after LF refining and RH treatment. The components obtained by the method are suitable for producing high-strength steel plates by controlled rolling and controlled cooling. If the yield strength of the normalized steel plate is over 355MPa, elements such as C, Mn, Nb, Ti and the like are inevitably improved, and an M-A phase is easy to appear in an HAZ overheating area during large-line welding, so that the toughness is poor; in order to achieve high toughness in the HAZ superheat zone during large-line welding, the C, Mn, Nb and Ti components need to be controlled to be in the middle and lower limits, and the yield strength is insufficient. In addition, nitrogen fixation elements are insufficient, and when too high N is introduced during smelting, there is a risk of aging embrittlement of the HAZ region outside the coarse crystal region due to nitrogen during high linear weldability.
Documents 11 "CN 109321847 a", 12 "CN 109321815A", 13 "CN 109321846A", 14 "CN 109321816A" and the like are all intended to apply large-line energy welding by controlling the timing of oxide formation and the composite structure and inducing phase transformation of needle ferrite in the austenite grains in the HAZ superheat region by fine composite oxides dispersed and distributed in a dispersed manner.
Although a great deal of research on normalized steel plates welded by large heat input exists in the prior art, the research is oriented to a production mode of controlled rolling and controlled cooling, and the problems that the applicability of large heat input welding and the strength after normalization cannot be considered simultaneously exist. Therefore, it is urgently required to develop a method for producing a normalized thick steel sheet having a sufficiently high yield strength suitable for large-line weldability.
Disclosure of Invention
Based on the analysis of the prior art, aiming at the defects of the prior art in producing the large-thickness normalizing steel plate with the thickness of more than 60mm suitable for large-line welding, the invention takes the strength and the large-line welding applicability into consideration, controls CeS, CaS and TiN inclusions to be formed in the steel in a dispersed way by reasonably blending the components, and controls the steel to form second-phase particle precipitates such as VN and the like after normalizing, thereby obtaining the 380 MPa-grade normalizing steel plate with the thickness of more than 40-180mm and excellent obdurability and large-line welding adaptability.
The specific scheme of the invention is as follows:
a method for manufacturing a normalized thick steel plate suitable for large-line weldable comprises the following steps: the obtained molten steel is taken as a raw material, a Ca alloy wire and a Ce alloy wire are fed, then argon is blown weakly at the bottom of a tank for stirring, a casting blank is obtained by pouring, iron oxide scales on the surface of the casting blank are removed, a steel plate is obtained by rolling, and a normalized thick steel plate is obtained by water cooling and normalizing.
Preferably, the process for obtaining the molten steel comprises the following steps: smelting in a converter, controlling a weak oxide forming element to pre-deoxidize, regulating and controlling the temperature of molten steel in an LF (ladle furnace), performing final deoxidation by using Ti, performing white slag making operation in the LF, performing vacuum degassing treatment and fine adjustment of components in an RH (relative humidity) process, feeding a nitrogenous alloy into the molten steel tank after RH is broken to empty, and controlling the nitrogen content to be within a target range.
Preferably, the molten steel comprises the following components in percentage by weight: 0.06-0.10%, Si: 0.10 to 0.30%, Mn: 1.50-1.60%, P is less than or equal to 0.012%, S: 0.001-0.003%, Cr is less than or equal to 0.20%, Ni: 0.20-0.30%, Cu: 0.20-0.30%, Mo is less than or equal to 0.06%, V: 0.08-0.10%, Ti: 0.007-0.013%, Nb: less than or equal to 0.020%, B: less than or equal to 0.0008 percent, Alt: less than or equal to 0.012%, free [ O ] less than or equal to 5PPm, and [ H ]: less than or equal to 2PPm, and the balance of Fe and inevitable impurity elements in steel.
Preferably, the N content satisfies 0.004% to N- [14 × (Ti/48+ Nb/92+ Al/27+ B/11) ]. to V/6.
Preferably, after RH vacuum treatment, feeding Ce alloy wires according to the Ce/S ratio of more than or equal to 1 and less than or equal to 2 in a finished product, feeding Ca alloy wires according to the Ca/S ratio of more than or equal to 0.8 and less than or equal to 1.8 in the finished product, stirring by blowing argon gas weakly at the bottom of a tank, controlling the flow of the argon gas according to the diameter (average diameter length) of the exposed surface on the surface of molten steel at a gas outlet point to be less than or equal to 80mm, stirring for 3-10 min, casting on a machine within 15min after argon gas blowing is finished, controlling the superheat degree of a tundish to be 15-25 ℃, and controlling the thickness of a cast blank to.
Preferably, the alloying is performed after RH in the order of Ce treatment and Ca treatment.
Preferably, the rolling process route is to heat the plate blank at 1150-1250 ℃ and finish hot rolling at 1100-800 ℃.
Preferably, the steel plate is cooled in air after rolling, or is cooled to 600-700 ℃ by water cooling and accelerating cooling, and then is subjected to air cooling.
Preferably, the steel plate is cooled to room temperature and then is subjected to normalizing treatment, and the normalizing heat preservation temperature is 880-920 ℃.
Preferably, soaking the obtained casting blank in a temperature range of 1150-1250 ℃, removing the iron oxide scale on the surface of the blank by high-pressure water spraying, rolling on a heavy and medium plate mill, producing a steel plate with the thickness of 40-180mm, controlling the total deformation rate to be more than or equal to 40% at 930-800 ℃, and controlling the temperature of red return to be 600-700 ℃ when the thickness of a finished product is more than 80mm by water cooling and accelerated cooling; when the thickness of the finished product is less than or equal to 80mm, the finished product can be naturally cooled in the air.
The steel plate produced by the method has the yield strength (ReH) of more than or equal to 380MPa, Rm of more than or equal to 490MPa and KV2 stabilized at the temperature of-20 ℃ of more than 120J. Welding under the welding line energy of 400-500 KJ/cm, and stabilizing the KV2 at-20 ℃ of a HAZ zone of a welded joint to be more than 80J.
Therefore, the control C: 0.06-0.10%, Si: 0.10 to 0.30%, Mn: 1.50-1.60% because these elements are less than the lower limit, do not contribute sufficiently to the strength of the steel, and do not easily make the post-normalization strength meet the requirements, and if they exceed the upper limit, the weld joint HAZ superheated zone tends to form an M-a phase, which is detrimental to toughness.
Therefore, the ratio of Cr: less than or equal to 0.20 percent, Mo: less than or equal to 0.06 percent, Nb: less than or equal to 0.020%, and also because the HAZ superheat zone of the welded joint is easy to form an M-A phase beyond this content, which is unfavorable for toughness.
Therefore, the control B: less than or equal to 0.0008 percent, Alt: less than or equal to 0.012 percent because the two elements are easy to combine with N, and the N forming a precipitation phase with V in the steel is abstracted, so that the precipitation strengthening amplitude of the steel is insufficient and is lower than the limited upper limit value, and the influence in the design is not obvious.
Therefore, the ratio of Ti: 0.007 to 0.013 percent, on one hand, because Ti can be combined with N in steel and forms TiN precipitation particles in a high-temperature region before V, the particles have obvious effect on inhibiting austenite coarsening. When the Ti content is less than 0.007%, most of TiN particles are dissolved back and the effect of inhibiting austenite coarsening disappears when the temperature is raised to 1350 ℃, but when the Ti content is more than 0.013%, TiN is precipitated in a liquid phase and the particle size is coarse, which is not favorable for the toughness of the steel.
Therefore, the control V: 0.08-0.10%, it is expected that V and N are combined into a fine VN coherent or semi-coherent precipitated phase in the normalizing process, so as to improve the ferrite matrix strength of the steel. Below 0.08% results in insufficient reinforcement in the present design, and above 0.10% increases the tendency for M-A phase to appear in the HAZ zone of the weld, which is detrimental to the toughness of the HAZ superheat zone.
The reason why the N content is controlled to be 0.004% to N- [ 14X (Ti/48+ Nb/92+ Al/27+ B/11) ]. ltoreq.V/6 is to ensure the strength of steel by forming a vanadium-nitrogen bonded precipitation phase of at least 0.004% or more of N and V in the steel, but if the N content fixed by Ti, Nb, Al and B is removed and the remaining N exceeds V/6, the tendency of aging embrittlement of the steel increases, so that the upper limit is controlled to V/6.
Therefore, it is desirable that the steel contains 0.001 to 0.003% of S, and a certain amount of S, Ce and Ca form fine inclusions of CeS (x), CaS (x) and the combination thereof in the molten steel, and the inclusions can strongly inhibit coarsening of austenite, and when the amount of the inclusions is less than 0.001%, the amount of the formed inclusions is insufficient to affect the effect of inhibiting coarsening of austenite, and when the amount of the formed inclusions is more than 0.003%, the coarsening of the grain size of the inclusions is remarkable, and the effect of inhibiting coarsening of austenite is reduced.
The reason why the free [ O ] is controlled to be less than or equal to 5PPm is that the free [ O ] in the steel preferentially reacts with Ca \ Ce, the content of the free [ O ] exceeds 5PPm, severe combination reaction can be caused when the Ce and Ca are alloyed subsequently, the Ce and Ca alloying operation can not be carried out, and formed inclusions can be coarsened.
The reason why [ H ] in the steel is controlled to be less than or equal to 2PPm is that the steel is polymerized at the casting blank defect position to form a hydrogen-induced crack or a hydrogen embrittlement defect when the limit value is exceeded, so that the flaw detection of a finished product is unqualified and the toughness is reduced.
The Ce alloy wire is controlled to be fed into the molten steel according to the condition that the content of Ce in a finished product is 1-2 times of the content of S, and the Ca alloy wire is controlled to be fed into the molten steel according to the condition that the content of Ca in the finished product is 0.8-1.8 times of the content of S, so that enough CeS (x), CaS (x) and composite inclusions thereof are formed in the steel, MnS segregation which is easy to deform does not exist in the steel, and the inclusions are fine and dispersed and do not float out of the molten steel. Because CeS (x) is high in specific gravity and is not easy to float out of molten steel, Ce alloying is preferentially carried out, so that CeS (x), CaS (x) and composite inclusions thereof are uniformly distributed; the Ca treatment is carried out after the Ce is alloyed, so that the formed inclusion has proper size and reasonable structure, and the CeS (x) -CaS (x) -MnS structure is formed at normal temperature, which is favorable for inducing the overheated austenite to generate the transformation of the acicular ferrite in the crystal. The Ce content is 1 time the S content and the Ca content is 0.8 time the S content, and the desired effect can be completely achieved. However, when the content of Ce exceeds 2 times the content of S and the content of Ca exceeds 1.8 times the content of S, the reducibility of the molten steel is increased, the corrosion resistance to the refractory is increased, and the flocculent large-particle inclusions are easily formed in the steel, which are disadvantageous in terms of the production order and the quality of the final product.
The normalizing temperature is selected to be 880-920 ℃, and is preferably 900 +/-5 ℃, because the strength and toughness of the steel plate in the temperature range are better matched.
Has the advantages that: the invention solves the problem of insufficient toughness of HAZ coarse crystal zone of a 360 MPa-level low-alloy ultra-thick normalized steel plate under the condition of ultra-large linear energy welding of more than 400KJ/cm, the base metal of the invented steel plate has the yield strength of more than 360MPa, the toughness of a Charpy impact value KV2 of not less than 80J at minus 40 ℃, the Charpy impact value KV2 of the HAZ zone of the invention stably reaches more than 80J at minus 20 ℃ under the condition of 400-500 KJ/cm large linear energy welding, and the steel plate is suitable for being used on thick steel plate structural members needing high-efficiency welding.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar modules or modules having the same or similar functionality throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
The invention provides a manufacturing method of a normalizing thick steel plate suitable for large-line energy welding, which comprises the following process routes of converter smelting, controlling weak oxide forming elements to pre-deoxidize, carrying out molten steel temperature regulation and control in an LF furnace, carrying out final deoxidation by using Ti, carrying out white slag manufacturing operation in the LF furnace, carrying out vacuum degassing treatment and fine adjustment of components in an RH process, feeding a nitrogen-containing alloy line into a molten steel tank after RH is broken to be empty, and controlling the nitrogen content to be in a target range. The obtained component is C: 0.06-0.10%, Si: 0.10 to 0.30%, Mn: 1.50-1.60%, P is less than or equal to 0.012%, S: 0.001-0.003%, Cr is less than or equal to 0.20%, Ni: 0.20-0.30%, Cu: 0.20-0.30%, Mo is less than or equal to 0.06%, V: 0.08-0.10%, Ti: 0.007-0.013%, Nb: less than or equal to 0.020%, B: less than or equal to 0.0008 percent, Alt: less than or equal to 0.012%, free [ O ] less than or equal to 5PPm, and [ H ]: the method comprises the steps of (1) molten steel with the PPm less than or equal to 2PPm and the N content less than or equal to 0.004% and less than or equal to N- [14 x (Ti/48+ Nb/92+ Al/27+ B/11) ], feeding a Ce alloy wire into the molten steel according to the Ce content of a finished product being 1-2 times of the S content, feeding a Ca alloy wire into the molten steel according to the Ca content of the finished product being 0.8-1.8 times of the S content, carrying out weak blowing and stirring, controlling the argon gas flow according to the diameter (average radial length) of a bare surface of the molten steel surface of an air outlet point being less than or equal to 80mm, stirring for 3-10 min, carrying out pouring on a continuous casting machine within 15min, controlling the superheat degree of a tundish to be 15-25 ℃, and controlling the thickness of a cast blank to be not less than 2.5 times of the thickness of a finished steel plate.
Soaking the obtained casting blank in a temperature range of 1150-1250 ℃, removing iron oxide scales on the surface of the blank by high-pressure water spraying, rolling on a medium plate mill to produce a steel plate with the thickness of 40-180mm, controlling the total deformation rate to be more than or equal to 40% at 930-800 ℃, and controlling the temperature of red return to be 600-700 ℃ when the thickness of a finished product is more than 80mm by water cooling accelerated cooling; when the thickness of the finished product is less than or equal to 80mm, the finished product can be naturally cooled in the air.
And normalizing the cooled steel plate, wherein the normalizing heat preservation temperature is 880-920 ℃, and the preferred temperature is 900 +/-5 ℃.
Example A1
Firstly, preprocessing molten iron used for smelting in a converter, controlling the content of S in the molten iron to be less than or equal to 0.010 percent and the content of P to be less than or equal to 0.08 percent, controlling elements such as C, Si, Mn, P and the like through composite blowing at the top and the bottom of the converter, and controlling the tapping temperature of the converter to be more than or equal to 1620 ℃. And then deoxidizing through Si and Mn, adjusting the temperature of molten steel in an LF furnace to ensure the tundish temperature during the on-machine process, further deoxidizing through alloys containing Si and Mn, calcium carbide and the like, carrying out Ti microalloying, carrying out white slag manufacturing operation on large slag amount in the LF furnace, controlling the total Al content to be less than or equal to 0.012%, adjusting alloy components except N and V to a control target, carrying out RH vacuum treatment, controlling the N and free O content, carrying out N content inspection and all control component inspection, adjusting the N and V content to the target through V iron and VN alloys, and further finely adjusting other alloys to the control target. Calculating the S content of the finished product, determining the wire feeding amount of Ce and Ca according to the calculated value, wherein Ce/S is 1.5, and Ca/S is 1.3, injecting pure Ce wires into the steel at the speed of 180-300 m/min, and then injecting Ca alloy wires into the steel at the speed of 180-300 m/min. Adding a low-nitrogen covering agent into the tank, starting argon at the bottom of the tank, adjusting the pressure and flow of the argon, and controlling the diameter of the exposed surface of the gas outlet point on the surface of the molten steel to be about 60 mm. Stirring for 5-10 min, calming for 9-13 min, and pouring on a machine, wherein the superheat degree of the tundish is controlled to be 15-25 ℃. The section of the casting blank is 320mm multiplied by 2000mm, the pulling speed is 0.83-0.86 m/min, and the solidification tail end is adopted for soft reduction. And stacking the casting blanks after the hot corner cleaning treatment. The tundish smelting components of the steel obtained by the process are A1, A2 and A3 in Table 1.
Wherein N of A1f＝N-[14×(Ti/48+Nb/92+Al/27+B/11)]＝0.0092-[14×(0.009/48+0.002/92+0.003/27+0.0004/11)]0.0042 and 0.014 for V/6, wherein Nf is more than or equal to 0.004 and less than or equal to V/6. Ce/S of a1 is 1.3 and Ca/S is 1.3. N is a radical offVariables representing the N element in the Steel, example N belowfThe meaning is the same.
Example A2
Firstly, preprocessing molten iron used for smelting in a converter, controlling the content of S in the molten iron to be less than or equal to 0.010 percent and the content of P to be less than or equal to 0.08 percent, controlling elements such as C, Si, Mn, P and the like through composite blowing at the top and the bottom of the converter, and controlling the tapping temperature of the converter to be more than or equal to 1620 ℃. And then deoxidizing through Si and Mn, adjusting the temperature of molten steel in an LF furnace to ensure the tundish temperature during the on-machine process, further deoxidizing through alloys containing Si and Mn, calcium carbide and the like, carrying out Ti microalloying, carrying out white slag manufacturing operation on large slag amount in the LF furnace, controlling the total Al content to be less than or equal to 0.012%, adjusting alloy components except N and V to a control target, carrying out RH vacuum treatment, controlling the N and free O content, carrying out N content inspection and all control component inspection, adjusting the N and V content to the target through V iron and VN alloys, and further finely adjusting other alloys to the control target. Calculating the S content of the finished product, determining the wire feeding amount of Ce and Ca according to the calculated value, wherein Ce/S is 1.5, and Ca/S is 1.3, injecting pure Ce wires into the steel at the speed of 180-300 m/min, and then injecting Ca alloy wires into the steel at the speed of 180-300 m/min. Adding a low-nitrogen covering agent into the tank, starting argon at the bottom of the tank, adjusting the pressure and flow of the argon, and controlling the diameter of the exposed surface of the gas outlet point on the surface of the molten steel to be about 60 mm. Stirring for 5-10 min, calming for 9-13 min, and pouring on a machine, wherein the superheat degree of the tundish is controlled to be 15-25 ℃. The section of the casting blank is 320mm multiplied by 2000mm, the pulling speed is 0.83-0.86 m/min, and the solidification tail end is adopted for soft reduction. And stacking the casting blanks after the hot corner cleaning treatment.
Wherein N of A2f＝N-[14×(Ti/48+Nb/92+Al/27+B/11)]＝0.011-[14×(0.010/48+0.003/92+0.002/27+0.0005/11)]0.0060 and 0.0148, wherein Nf is more than or equal to 0.004 and less than or V/6. Ce/S of a2 is 1.1 and Ca/S is 1.0.
Example A3
Firstly, preprocessing molten iron used for smelting in a converter, controlling the content of S in the molten iron to be less than or equal to 0.010 percent and the content of P to be less than or equal to 0.08 percent, controlling elements such as C, Si, Mn, P and the like through composite blowing at the top and the bottom of the converter, and controlling the tapping temperature of the converter to be more than or equal to 1620 ℃. And then deoxidizing through Si and Mn, adjusting the temperature of molten steel in an LF furnace to ensure the tundish temperature during the on-machine process, further deoxidizing through alloys containing Si and Mn, calcium carbide and the like, carrying out Ti microalloying, carrying out white slag manufacturing operation on large slag amount in the LF furnace, controlling the total Al content to be less than or equal to 0.012%, adjusting alloy components except N and V to a control target, carrying out RH vacuum treatment, controlling the N and free O content, carrying out N content inspection and all control component inspection, adjusting the N and V content to the target through V iron and VN alloys, and further finely adjusting other alloys to the control target. Calculating the S content of the finished product, determining the wire feeding amount of Ce and Ca according to the calculated value, wherein Ce/S is 1.5, and Ca/S is 1.3, injecting pure Ce wires into the steel at the speed of 180-300 m/min, and then injecting Ca alloy wires into the steel at the speed of 180-300 m/min. Adding a low-nitrogen covering agent into the tank, starting argon at the bottom of the tank, adjusting the pressure and flow of the argon, and controlling the diameter of the exposed surface of the gas outlet point on the surface of the molten steel to be about 60 mm. Stirring for 5-10 min, calming for 9-13 min, and pouring on a machine, wherein the superheat degree of the tundish is controlled to be 15-25 ℃. The section of the casting blank is 320mm multiplied by 2000mm, the pulling speed is 0.83-0.86 m/min, and the solidification tail end is adopted for soft reduction. And stacking the casting blanks after the hot corner cleaning treatment.
Wherein N of A3f＝N-[14×(Ti/48+Nb/92+Al/27+B/11)]＝0.0125-[14×(0.013/48+0.005/92+0.005/27+0.0005/11)]0.0047 and 0.0155 satisfy Nf and V/6 of 0.004 and not more than V/6. Ce/S of a3 is 1.6 and Ca/S is 1.8.
Example A4
Firstly, preprocessing molten iron used for smelting in a converter, controlling the content of S in the molten iron to be less than or equal to 0.010 percent and the content of P to be less than or equal to 0.08 percent, controlling elements such as C, Si, Mn, P and the like through composite blowing at the top and the bottom of the converter, and controlling the tapping temperature of the converter to be more than or equal to 1620 ℃. And then deoxidizing through Si and Mn, adjusting the temperature of molten steel in an LF furnace to ensure the tundish temperature during the on-machine process, further deoxidizing through alloys containing Si and Mn, calcium carbide and the like, carrying out Ti microalloying, carrying out white slag manufacturing operation on large slag amount in the LF furnace, controlling the total Al content to be less than or equal to 0.012%, adjusting alloy components except N and V to a control target, carrying out RH vacuum treatment, controlling the N and free O content, carrying out N content inspection and all control component inspection, adjusting the N and V content to the target through V iron and VN alloys, and further finely adjusting other alloys to the control target. Calculating the S content of the finished product, determining the wire feeding amount of Ce and Ca according to the calculated value, wherein Ce/S is 1.5, and Ca/S is 1.3, injecting pure Ce wires into the steel at the speed of 180-300 m/min, and then injecting Ca alloy wires into the steel at the speed of 180-300 m/min. Adding a low-nitrogen covering agent into the tank, starting argon at the bottom of the tank, adjusting the pressure and flow of the argon, and controlling the diameter of the exposed surface of the gas outlet point on the surface of the molten steel to be about 60 mm. Stirring for 5-10 min, calming for 9-13 min, and pouring on a machine, wherein the superheat degree of the tundish is controlled to be 15-25 ℃. The section of the casting blank is 320mm multiplied by 2000mm, the pulling speed is 0.83-0.86 m/min, and the solidification tail end is adopted for soft reduction. And stacking the casting blanks after the hot corner cleaning treatment.
Wherein N of A4f＝N-[14×(Ti/48+Nb/92+Al/27+B/11)]＝0.013-[14×(0.009/48+0.005/92+0.005/27+0.0004/11)]0.0065, 0.016 satisfies Nf and V/6 of 0.004 and 6. Ce/S of a4 is 1.14 and Ca/S is 1.07.
Comparative examples B1 and B2
Compared with steel grades B1 and B2, the low-phosphorus molten steel is smelted by adopting the traditional process, the converter is used for smelting the low-phosphorus molten steel, the deoxidization is not limited by a deoxidizer after tapping, the condition is created for the operation of making white slag by LF (ladle furnace) by strengthening the deoxidizer AL for pre-deoxidization, the alloying is completed by adjusting the temperature in the LF furnace, and the white slag is made and kept for more than 10 min. Performing RH degassing treatment after LF treatment, feeding Ca wire after RH treatment, stirring for 10min by weak argon blowing, calming for 11 min and pouring on a machine after 12min, wherein the average superheat degree of the tundish is 18 ℃ and 22 ℃ respectively. The control of the casting blank section and the drawing speed of the comparative steel is basically consistent with that of the steel of the invention, and the solidification tail end is also adopted for soft reduction. The RH processing parameters for the inventive steels and the comparative steel grades are listed in Table 2.
The steel plate manufacturing process comprises the following steps: the steel grades A1, A2, A3 and A4 of the invention and the comparative steel grades B1 and B2 are all subjected to slab heating by a walking beam heating furnace, rolled on a wide and thick plate rolling mill into a steel plate with the thickness of 60mm by adopting a two-stage rolling method, and air-cooled after rolling or sprayed water after rolling. Controlling the temperature of the re-reddening by water spray cooling to be over 620 ℃, then carrying out normalizing treatment in a roller-hearth continuous heat treatment furnace after shot blasting treatment, wherein the set normalizing temperature is 900 ℃, and the net heat preservation time is 30 min.
The main rolling processes for the inventive steels and the comparative steels are listed in table 3. The results of the steel sheet property test after normalizing are shown in Table 4. A welding test plate is taken from the steel of the invention and the comparative steel, the length direction of a welding line is parallel to the length direction of the steel plate, butt welding is carried out by a double-wire electric vertical welder, the adopted welding parameters and welding wires are shown in a table 5, and the impact toughness test results of a welding joint are shown in a table 6 and a table 7.
Table 4 shows that the yield strength of the A1, A2, A3 and A4 steel plates of the invention is stable above 380MPa, the impact toughness is stable, and the difference is not large compared with the traditional clean smelting comparison steel, and tables 6 and 7 show that the impact toughness of the welding seam of the steel of the invention is far better than that of the comparison steel under the welding condition of the linear energy of above 400Kj/cm, the steel is applied to large linear energy welding, and the performance of the welding seam area is safe and reliable.
TABLE 1 melting analysis composition
TABLE 2 main relevant control operation parameters for continuous casting to the upper machine after RH breaking
TABLE 3 thickness of finished product, rolling process and Heat treatment Process parameters of the composition billet-rolled steel sheets of each example
TABLE 4 mechanical Properties after normalization of the steel sheets rolled with the compositions of the examples
Table 5 welding process of steel plates rolled with each example composition
TABLE 6 weld joint impact toughness for each composition number (1/4 thickness position)
TABLE 7 weld joint impact toughness for each composition number (1/2 thickness position)
In the description herein, references to the description of "one embodiment," "another embodiment," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (5)
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