CN115125443B - High-toughness easy-to-weld steel and preparation method thereof - Google Patents
High-toughness easy-to-weld steel and preparation method thereof Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 119
- 239000010959 steel Substances 0.000 title claims abstract description 119
- 238000002360 preparation method Methods 0.000 title claims abstract description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 61
- 229910052742 iron Inorganic materials 0.000 claims abstract description 30
- 239000012535 impurity Substances 0.000 claims abstract description 15
- 239000000126 substance Substances 0.000 claims abstract description 15
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 14
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 12
- 238000004519 manufacturing process Methods 0.000 claims abstract description 12
- 238000005096 rolling process Methods 0.000 claims description 79
- 238000001816 cooling Methods 0.000 claims description 46
- 238000010438 heat treatment Methods 0.000 claims description 45
- 238000009749 continuous casting Methods 0.000 claims description 33
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 33
- 238000005266 casting Methods 0.000 claims description 22
- 229910001294 Reinforcing steel Inorganic materials 0.000 claims description 12
- 238000007670 refining Methods 0.000 claims description 12
- 238000003723 Smelting Methods 0.000 claims description 11
- 239000000498 cooling water Substances 0.000 claims description 11
- 238000009847 ladle furnace Methods 0.000 claims description 11
- 238000005507 spraying Methods 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 7
- 101100366060 Caenorhabditis elegans snap-29 gene Proteins 0.000 claims description 6
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- 230000002787 reinforcement Effects 0.000 claims description 3
- 238000003466 welding Methods 0.000 abstract description 25
- 229910052720 vanadium Inorganic materials 0.000 abstract description 10
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 7
- 230000007547 defect Effects 0.000 abstract description 4
- 239000011572 manganese Substances 0.000 description 23
- 230000000052 comparative effect Effects 0.000 description 8
- 229910001566 austenite Inorganic materials 0.000 description 7
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
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- 238000010276 construction Methods 0.000 description 3
- 238000005098 hot rolling Methods 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- INZDTEICWPZYJM-UHFFFAOYSA-N 1-(chloromethyl)-4-[4-(chloromethyl)phenyl]benzene Chemical compound C1=CC(CCl)=CC=C1C1=CC=C(CCl)C=C1 INZDTEICWPZYJM-UHFFFAOYSA-N 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 2
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- 239000007921 spray Substances 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 1
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- 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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/16—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- 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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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Abstract
The invention discloses high-toughness easy-to-weld steel and a preparation method thereof, wherein the high-toughness easy-to-weld steel comprises the following chemical components in percentage by mass: 0.14-0.18% of C, 0.35-0.55% of Si, 0.80-1.00% of Mn, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.005-0.020% of Al, 0.05-0.08% of V, 0.0060-0.0080% of N, and the balance of iron and unavoidable impurities, wherein the carbon equivalent Ceq=C+Mn/6+V/5,0.28% < Ceq less than or equal to 0.38%. On the basis of overcoming the defect of poor welding performance of the traditional steel bar, the steel provided by the invention has high toughness and easy welding performance by reducing the carbon equivalent and adding V, N, al and other elements on the premise of not affecting the mechanical performance, and meets the industrial intelligent manufacturing requirement of the bridge.
Description
Technical Field
The invention relates to the technical field of reinforcing steel bars for bridges, in particular to high-toughness easy-to-weld steel and a preparation method thereof.
Background
Along with the development of modern bridges to large scale and large span, the bridge manufacturing industry is changed from traditional labor intensive, poor manufacturing environment and unstable manufacturing quality to industrialized and digital construction, and is integrated with advanced intelligent manufacturing technology and developed to intelligent construction direction, so that higher requirements are put forward on materials for bridge manufacturing. The traditional bridge tower bridge construction is before the concrete pouring, and its vertical main muscle of reinforcing bar and horizontal stirrup cloth are connected and need lean on the constructor to carry out artifical ligature on the tower bridge, not only inefficiency, ligature quality is unstable, easy slip, and the security is poor moreover. The industrial manufacturing of the modern bridge adopts a robot automatic welding mode to connect the longitudinal main reinforcement and the transverse stirrup of the reinforcing steel bar, so that the production efficiency is improved, the quality is stable and reliable, and no potential safety hazard exists; however, after the conventional steel bars are welded by the longitudinal main bars and the transverse stirrup cloth, the welding heat affected zone affects the performance of the main bars, and the requirements of design safety cannot be met.
Patent CN 165586538A discloses a high strength high weldability steel bar. The strength, corrosion resistance and welding performance of the steel are improved by adding a large amount of precious alloy such as Nb, V, ti, ni, cr, mo, cu and the like into the steel, and the steel comprises the following components in percentage by weight: 0.06-0.10% of C, 0.15-0.50% of Si, 0.40-0.60% of Mn, 0.05-0.08% of V, 0.01-0.05% of Ti, 0.01-0.05% of Nb, 0.01-0.02% of Ni, 0.2-0.5% of Cr, 0.1-0.2% of Mo, 0.2-0.5% of Cu and the balance of Fe and unavoidable impurities. The yield strength of the steel is more than 610MPa, and the carbon content is less than 0.40 percent. The method has the defects that a large amount of precious alloy elements are added, so that compared with the traditional HRB400E, the method has the advantages that the cost is greatly increased, meanwhile, the steel is added with high hardenability and heat embrittlement elements Cr, mo, cu and the like, a large amount of martensite is easily formed in a welding heat affected zone, stress concentration is easily generated due to stress, and brittle fracture occurs.
The patent CN 105648307A discloses a high-strength steel bar, which relates to the technical field of building materials and comprises the following chemical components in percentage by mass: c less than or equal to 0.15%, si0.2-0.4%, mn0.3-0.6%, S less than or equal to 0.03%, P less than or equal to 0.03%, V0.1-0.2%, ni0.01-0.03%, cr less than or equal to 0.1%, mo0.06-0.08%, al0.006-0.01%, and Fe and unavoidable impurities as the rest. The yield strength reaches 700MPa, but the elongation is only about 10 percent, and the plasticity is low.
Patent CN 108977729A discloses a high-strength reinforcing steel bar, which comprises the following components, by weight, 0.23-0.28% of C, 0.50-0.70% of Si, 1.30-1.60% of Mn, 0.060-0.080% of V, and the balance of Fe, wherein the impurity content is controlled: s is less than or equal to 0.045%, P is less than or equal to 0.045%, the yield strength is more than 600MPa, the elongation is only 20%, the plasticity is poor, and the carbon equivalent is more than 0.50, so that the welding is not facilitated.
In view of the fact that the existing steel bar patents cannot meet the industrial intelligent manufacturing requirements of modern large-scale bridges in terms of cost, welding performance and the like, the high-toughness easy-to-weld steel capable of guaranteeing high strength and shock resistance needs to be developed, toughness is improved, welding performance is improved, and the industrial intelligent manufacturing requirements of the large-scale bridges are met.
Disclosure of Invention
The invention aims to solve the defects of the background technology and provide high-toughness easy-to-weld steel with high strength and shock resistance.
The technical scheme of the invention is as follows:
the invention aims to provide high-toughness easy-to-weld steel, which comprises the following chemical components in percentage by mass:
C 0.14-0.18％，
Si 0.35-0.55％，
Mn 0.80-1.00％，
P≤0.015％，
S≤0.010％，
Al 0.005-0.020％，
V 0.05-0.08％，
N 0.0060-0.0080％，
the balance of iron and unavoidable impurities,
wherein the carbon equivalent Ceq=C+Mn/6+V/5,0.28% < Ceq.ltoreq.0.38%.
In the invention, the carbon equivalent Ceq is the sum of C percentage, mn percentage of 1/6 and V percentage of 1/5.
Preferably, the composition comprises the following chemical components in percentage by mass:
C 0.14-0.16％，
Si 0.4-0.48％，
Mn 0.85-1.00％，
P≤0.015％，
S≤0.010％，
Al 0.01-0.016％，
V 0.065-0.08％，
N 0.0062-0.0072％，
the balance of iron and unavoidable impurities,
0.3％≤Ceq≤0.35％。
further, the method comprises the following chemical components in percentage by mass:
C 0.14％，
Si 0.45％，
Mn 0.90％，
P 0.010％，
S 0.004％，
Al 0.015％，
V 0.070％，
N 0.0072％，
the balance of iron and unavoidable impurities.
Furthermore, the yield strength of the high-toughness easy-to-weld steel is more than or equal to 420MPa, the tensile strength is more than or equal to 550MPa, and the elongation is more than or equal to 30%.
Furthermore, after the high-toughness easy-to-weld steel is used as a main reinforcement and welded with stirrups, the yield strength is more than or equal to 420MPa, the tensile strength is more than or equal to 550MPa, and the elongation is more than or equal to 30%.
Further, the fracture area is positioned in a non-welding and heat affected zone during the tensile test of the high-toughness easy-to-weld steel, and the fracture is a toughness fracture.
The second object of the invention is to provide a method for preparing the high-toughness easy-to-weld steel, which comprises the following steps:
s1, smelting molten iron through a converter, refining the molten iron in a ladle furnace, and pouring the molten iron into a square billet through a continuous casting tundish and a crystallizer; the temperature of the molten steel of the continuous casting tundish is 1530-1560 ℃, and the cooling water flow of the crystallizer is 2200-2400L/min; the temperature of the casting blank after being cooled by water spraying is 950-1000 ℃ and the pulling speed of the casting blank is 3.2-3.6 m/min;
s2, loading the continuous casting billet into a billet heating furnace for heating, wherein the temperature of a heating section is 1100-1180 ℃ and the heating time is 80-120 min;
s3, after the heated square billet is subjected to high-pressure water descaling, the square billet enters a high-rigidity short-stress continuous rolling unit to be rolled into a threaded steel bar with the diameter of 28mm to 40mm, the rolling is divided into three stages of initial rolling, middle rolling and finish rolling, wherein the finish rolling temperature is 950 ℃ to 1000 ℃, the steel bar after finish rolling is subjected to water cooling, and then the steel bar enters a cooling bed to be subjected to air cooling.
Preferably, in step S1, the square billet has a cross-sectional dimension of 150mm x 150mm to 170mm x 170mm.
Preferably, in the step S3, a high-rigidity short-stress continuous rolling unit is adopted to roll the steel bars into the threaded steel bars with the diameter of phi 28mm to phi 40 mm.
Preferably, the temperature of the reinforcing steel bar entering the cooling bed in the step S3 is 900-950 ℃.
Preferably, the method comprises the following steps:
s1, smelting molten iron by a converter, refining by a ladle furnace, and pouring into a continuous casting tundish and a crystallizer to form square billets with the cross sections of 150mm multiplied by 150mm to 170mm multiplied by 170 mm; the molten steel temperature of the continuous casting tundish is 1536 ℃, and the cooling water flow of the crystallizer is 2250L/min; the temperature of the casting blank after being cooled by water spraying is 995 ℃ and the drawing speed of the casting blank is 3.3m/min.
S2, loading the continuous casting billet into a billet heating furnace for heating, wherein the temperature of a heating section is 1150 ℃, and the heating time is 110min.
S3, after the heated square billet is subjected to descaling by high-pressure water, the square billet enters a high-rigidity short-stress continuous rolling unit to be rolled into a threaded steel bar with the diameter of 28 mm-40 mm, the rolling is divided into three stages of initial rolling, middle rolling and finish rolling, wherein the finish rolling temperature is 980 ℃, the steel bar after finish rolling is subjected to water cooling, then the steel bar enters a cooling bed to be subjected to air cooling, and the temperature of the steel bar entering the cooling bed is 920 ℃.
The beneficial effects of the invention are as follows:
1. the carbon content has important influence on the strength and welding performance of the steel. The higher the carbon content, the higher the strength of the steel, the greater the hardening tendency of the heat affected zone, the greater the tendency to cold crack, and the poorer the weldability. Therefore, the invention adopts lower carbon content to ensure the welding performance of the steel; meanwhile, manganese has great influence on the toughness of welded seams of the steel, and the proper manganese content is favorableEnsuring the strength and toughness of weld metal; silicon is deoxidized element and has strong solid solution strengthening effect in steel, but SiO generated by the reaction of silicon and oxygen in steel during welding 2 The floating removal is difficult, slag inclusion is easy to form in the welding seam, and the welding performance is affected, so the Si and Mn contents in the invention are designed to be 0.35-0.55% and 0.80-1.00%.
2. According to the invention, a proper amount of V, N is added to enable the austenite to be separated out in the steel in the form of separated-out phases such as VN, VC, V (C, N) and the like, so that austenite grains can be refined, and the toughness of the steel can be improved. Vanadium carbo-nitrides have a large solubility in steel, while their nitrides have a solubility about two orders of magnitude lower than carbides, in contrast to Nb, which is similar to Ti. Because V has a greater solubility in austenite, coarse vanadium carbonitride compounds prior to hot rolling are also more soluble than vanadium carbide. The relatively high solubility of vanadium carbonitride plus the much lower solubility of vanadium nitride than vanadium carbide makes vanadium an element that is easy to control and has a strong precipitation strengthening effect. Therefore, vanadium and nitrogen are added into the steel, and small carbon and nitride dispersed particles can play a role in pinning a welded austenite grain boundary, so that migration of the austenite grain boundary is blocked, namely, the growth of the austenite grain is prevented.
Al is taken as a strong deoxidizing element, so that the oxygen content in steel can be effectively reduced, meanwhile, aluminum nitride formed by Al and nitrogen in the steel can be separated out as fine aluminum nitride particles along with solidification of molten steel, and austenite grains can be effectively prevented from growing and refining during rolling heating and welding.
4. According to the invention, the P, S content in the steel is strictly controlled, the influence on the welding performance of the steel is reduced as much as possible, and the toughness is improved.
5. On the basis of overcoming the defect of poor welding performance of the traditional steel bar, the steel provided by the invention has high toughness and easy welding performance by reducing the carbon equivalent and adding V, N, al and other elements on the premise of not affecting the mechanical performance, and meets the industrial intelligent manufacturing requirement of the bridge.
Drawings
FIG. 1 is a diagram showing fracture parts and cross-section morphology of a high toughness easy-to-weld steel according to the present invention
FIG. 2 is a partial view and a sectional view of a fracture zone of a conventional steel material
Detailed Description
The invention is illustrated in further detail by the following specific examples.
Example 1
The high-toughness easy-to-weld steel of the embodiment comprises the following chemical components in percentage by mass: 0.18% of C, 0.35% of Si, 0.82% of Mn, 0.012% of P, 0.010% of S, 0.008% of Al, 0.061% of V, 0.0070% of N, ceq=C+Mn/6+V/5=0.33% of Ceq=C+Mn/6+V/5%, and the balance of iron and unavoidable impurities.
The preparation method comprises the following steps:
s1, smelting molten iron by a converter, refining by a ladle furnace, and pouring into a continuous casting tundish and a crystallizer to form square billets with the cross sections of 150mm multiplied by 150mm to 170mm multiplied by 170 mm; the molten steel temperature of the continuous casting tundish is 1540 ℃, and the cooling water flow of the crystallizer is 2300L/min; the temperature of the casting blank after being cooled by water spraying is 970 ℃ and the pulling speed of the casting blank is 3.3m/min.
S2, loading the continuous casting billet into a billet heating furnace for heating, wherein the temperature of a heating section is 1135 ℃, and the heating time is 115min.
S3, after the heated square billet is subjected to descaling by high-pressure water, the square billet enters a high-rigidity short-stress continuous rolling unit to be rolled into a threaded steel bar with the diameter of 28mm to 40mm, the rolling is divided into three stages of initial rolling, middle rolling and finish rolling, wherein the finish rolling temperature is 990 ℃, the steel bar after finish rolling is subjected to water cooling, then the steel bar enters a cooling bed to be subjected to air cooling, and the temperature of the steel bar entering the cooling bed is 945 ℃.
Example 2
The high-toughness easy-to-weld steel of the embodiment comprises the following chemical components in percentage by mass: 0.16% of C, 0.40% of Si, 0.85% of Mn, 0.009% of P, 0.006% of S, 0.010% of Al, 0.065% of V, 0.0066% of N, ceq=C+Mn/6+V/5=0.31% of Ceq=C+Mn/6+V/5%, and the balance of iron and unavoidable impurities.
The preparation method comprises the following steps:
s1, smelting molten iron by a converter, refining by a ladle furnace, and pouring into a continuous casting tundish and a crystallizer to form square billets with the cross sections of 150mm multiplied by 150mm to 170mm multiplied by 170 mm; the molten steel temperature of the continuous casting tundish is 1550 ℃, and the cooling water flow of the crystallizer is 2320L/min; after the casting blank leaves the crystallizer, the temperature is 975 ℃ after water spray cooling, and the drawing speed of the casting blank is 3.4m/min.
S2, loading the continuous casting billet into a billet heating furnace for heating, wherein the temperature of a heating section is 1165 ℃, and the heating time is 95min.
S3, after the heated square billet is subjected to descaling by high-pressure water, the square billet enters a high-rigidity short-stress continuous rolling unit to be rolled into a threaded steel bar with the diameter of phi 28 mm-phi 40mm, the rolling is divided into three stages of initial rolling, intermediate rolling and finish rolling, wherein the finish rolling temperature is 975 ℃, the steel bar after finish rolling is subjected to water cooling, then the steel bar enters a cooling bed to be subjected to air cooling, and the temperature of the steel bar entering the cooling bed is 945 ℃.
Example 3
The high-toughness easy-to-weld steel of the embodiment comprises the following chemical components in percentage by mass: 0.14% of C, 0.45% of Si, 0.90% of Mn, 0.10% of P, 0.004% of S, 0.015% of Al, 0.070% of V, 0.0072% of N, ceq=C+Mn/6+V/5=0.30% of Ceq=C+Mn/6+V/5%, and the balance of iron and unavoidable impurities.
The preparation method comprises the following steps:
s1, smelting molten iron by a converter, refining by a ladle furnace, and pouring into a continuous casting tundish and a crystallizer to form square billets with the cross sections of 150mm multiplied by 150mm to 170mm multiplied by 170 mm; the molten steel temperature of the continuous casting tundish is 1536 ℃, and the cooling water flow of the crystallizer is 2250L/min; the temperature of the casting blank after being cooled by water spraying is 995 ℃ and the drawing speed of the casting blank is 3.3m/min.
S2, loading the continuous casting billet into a billet heating furnace for heating, wherein the temperature of a heating section is 1150 ℃, and the heating time is 110min.
S3, after the heated square billet is subjected to descaling by high-pressure water, the square billet enters a high-rigidity short-stress continuous rolling unit to be rolled into a threaded steel bar with the diameter of 28 mm-40 mm, the rolling is divided into three stages of initial rolling, middle rolling and finish rolling, wherein the finish rolling temperature is 980 ℃, the steel bar after finish rolling is subjected to water cooling, then the steel bar enters a cooling bed to be subjected to air cooling, and the temperature of the steel bar entering the cooling bed is 920 ℃.
Example 4
The high-toughness easy-to-weld steel of the embodiment comprises the following chemical components in percentage by mass: 0.14% of C, 0.48% of Si, 1.00% of Mn, 0.013% of P, 0.008% of S, 0.016% of Al, 0.080% of V, 0.0062% of N, ceq=C+Mn/6+V/5=0.32% of Ceq=C+Mn/6+V/5%, and the balance of iron and unavoidable impurities.
The preparation method comprises the following steps:
s1, smelting molten iron by a converter, refining by a ladle furnace, and pouring into a continuous casting tundish and a crystallizer to form square billets with the cross sections of 150mm multiplied by 150mm to 170mm multiplied by 170 mm; the molten steel temperature of the continuous casting tundish is 1530 ℃, and the cooling water flow of the crystallizer is 2220L/min; the temperature of the casting blank after being cooled by water spraying is 988 ℃ and the drawing speed of the casting blank is 3.5m/min.
S2, loading the continuous casting billet into a billet heating furnace for heating, wherein the temperature of a heating section is 1150 ℃, and the heating time is 90min.
S3, after the heated square billet is subjected to descaling by high-pressure water, the square billet enters a high-rigidity short-stress continuous rolling unit to be rolled into a threaded steel bar with the diameter of phi 28 mm-phi 40mm, the rolling is divided into three stages of initial rolling, middle rolling and finish rolling, wherein the finish rolling temperature is 965 ℃, the steel bar after finish rolling is subjected to water cooling, then the steel bar enters a cooling bed to be subjected to air cooling, and the temperature of the steel bar entering the cooling bed is 925 ℃.
Example 5
The high-toughness easy-to-weld steel of the embodiment comprises the following chemical components in percentage by mass: 0.15% C, 0.37% Si, 0.98% Mn, 0.011% P, 0.007% S, 0.007% Al, 0.072% V, 0.0075% N, ceq=c+mn/6+V/5=0.33%, the balance being iron and unavoidable impurities.
The preparation method comprises the following steps:
s1, smelting molten iron by a converter, refining by a ladle furnace, and pouring into a continuous casting tundish and a crystallizer to form square billets with the cross sections of 150mm multiplied by 150mm to 170mm multiplied by 170 mm; the temperature of the molten steel of the continuous casting tundish is 1535 ℃, and the cooling water flow of the crystallizer is 2200L/min; the temperature of the casting blank after being cooled by water spraying is 960 ℃ and the drawing speed of the casting blank is 3.2m/min.
S2, loading the continuous casting billet into a billet heating furnace for heating, wherein the temperature of a heating section is 1100 ℃, and the heating time is 110min.
S3, after the heated square billet is subjected to descaling by high-pressure water, the square billet enters a high-rigidity short-stress continuous rolling unit to be rolled into a threaded steel bar with the diameter of phi 28 mm-phi 40mm, the rolling is divided into three stages of initial rolling, middle rolling and finish rolling, wherein the finish rolling temperature is 960 ℃, the steel bar after finish rolling is subjected to water cooling, then the steel bar enters a cooling bed to be subjected to air cooling, and the temperature of the steel bar entering the cooling bed is 930 ℃.
Example 6
The high-toughness easy-to-weld steel of the embodiment comprises the following chemical components in percentage by mass: 0.17% of C, 0.52% of si, 0.88% of Mn, 0.009% of P, 0.004% of S, 0.006% of Al, 0.060% of V, 0.0076% of N, ceq=c+mn/6+V/5=0.33% of iron and unavoidable impurities in balance.
The preparation method comprises the following steps:
s1, smelting molten iron by a converter, refining by a ladle furnace, and pouring into a continuous casting tundish and a crystallizer to form square billets with the cross sections of 150mm multiplied by 150mm to 170mm multiplied by 170 mm; the molten steel temperature of the continuous casting tundish is 1555 ℃, and the cooling water flow of the crystallizer is 2350L/min; after the casting blank is discharged from the crystallizer, the temperature is 990 ℃ after water spray cooling, and the drawing speed of the casting blank is 3.6m/min.
S2, loading the continuous casting billet into a billet heating furnace for heating, wherein the temperature of a heating section is 1170 ℃, and the heating time is 85min.
S3, after the heated square billet is subjected to descaling by high-pressure water, the square billet enters a high-rigidity short-stress continuous rolling unit to be rolled into a threaded steel bar with the diameter of phi 28 mm-phi 40mm, the rolling is divided into three stages of initial rolling, middle rolling and finish rolling, wherein the finish rolling temperature is 965 ℃, the steel bar after finish rolling is subjected to water cooling, then the steel bar enters a cooling bed to be subjected to air cooling, and the temperature of the steel bar entering the cooling bed is 950 ℃.
Performance testing
Two existing steels were selected as the comparative steels, and the chemical compositions of the high-toughness easy-to-weld steels and the comparative steels in examples 1 to 6 are shown in the following Table 1. The hot rolling properties and the post-weld properties of the steel are shown in Table 2 below.
TABLE 1 chemical composition (wt%) of inventive and comparative steels
TABLE 2 Hot rolling Properties and post-weld Properties of inventive and comparative steels
As can be seen from the data in Table 2, the yield strength of the high-toughness easy-to-weld steel prepared by the invention is 425-450MPa, the tensile strength is 565-590MPa, the elongation data is 31-34%, and the elongation is at least 1.7 times that of the comparative steel; the yield strength data after welding is 425-445MPa, the tensile strength data is 570-585MPa, the elongation data is 31-34%, and the elongation after welding is at least more than 2.6 times of that of the comparative steel.
The high-toughness easy-to-weld steel prepared by the invention and the comparative steel 1 are welded and tensile tested according to JGJ18-2012, GB/28900-2012 and GB/T1499.2-2018, the fracture parts are shown in figure 1, the steel bars are broken in a non-welding area, and the fracture is a ductile fracture, so that the high-toughness easy-to-weld steel prepared by the invention has good welding performance, and the comparative steel 1 is broken in a welding area, the fracture is a brittle fracture and the welding performance is poor, as shown in figure 2.
Claims (5)
1. The high-toughness easy-to-weld steel is characterized by comprising the following chemical components in percentage by mass:
C 0.14-0.16％，
Si 0.4-0.48％，
Mn 0.85-1.00％，
P≤0.013％，
S≤0.008％，
Al 0.01-0.016％，
V 0.065-0.08％，
N 0.0062-0.0072％，
the balance of iron and unavoidable impurities,
wherein the carbon equivalent Ceq=C+Mn/6+V/5,0.3% Ceq is less than or equal to 0.32%;
the yield strength of the high-toughness easy-to-weld steel is more than or equal to 420MPa, the tensile strength is more than or equal to 550MPa, and the elongation is more than or equal to 30%;
after the high-toughness easy-to-weld steel is used as the main reinforcement and welded with the stirrup, the yield strength is not less than
420MPa, tensile strength is more than or equal to 550MPa, and elongation is more than or equal to 30%;
the preparation method of the high-toughness easy-to-weld steel comprises the following steps:
s1, smelting molten iron through a converter, refining the molten iron in a ladle furnace, and pouring the molten iron into a square billet through a continuous casting tundish and a crystallizer; the temperature of the molten steel of the continuous casting tundish is 1530-1560 ℃, and the cooling water flow of the crystallizer is 2200-2400L/min; the temperature of the casting blank after being cooled by water spraying is 950-1000 ℃ and the pulling speed of the casting blank is 3.2-3.6 m/min;
s2, loading the continuous casting billet into a billet heating furnace for heating, wherein the temperature of a heating section is 1100-1180 ℃ and the heating time is 80-120 min;
s3, after the heated square billet is subjected to descaling by high-pressure water, the square billet enters a high-rigidity short-stress continuous rolling unit to be rolled into a threaded reinforcing steel bar with the diameter of phi 28 mm-phi 40mm, the rolling is divided into three stages of initial rolling, intermediate rolling and finish rolling, wherein the finish rolling temperature is 950-1000 ℃, the reinforcing steel bar after finish rolling is subjected to water cooling, then the reinforcing steel bar enters a cooling bed to be subjected to air cooling, and the temperature of the reinforcing steel bar entering the cooling bed is 900-950 ℃.
2. The high toughness easy weld steel according to claim 1, comprising the following chemical composition in mass percent:
C 0.14％，
Si 0.45％，
Mn 0.90％，
P 0.010％，
S 0.004％，
Al 0.015％，
V 0.070％，
N 0.0072％，
the balance of iron and unavoidable impurities.
3.A method of producing a high toughness weldable steel according to any one of claims 1-2, comprising the steps of:
s1, smelting molten iron through a converter, refining the molten iron in a ladle furnace, and pouring the molten iron into a square billet through a continuous casting tundish and a crystallizer; the temperature of the molten steel of the continuous casting tundish is 1530-1560 ℃, and the cooling water flow of the crystallizer is 2200-2400L/min; the temperature of the casting blank after being cooled by water spraying is 950-1000 ℃ and the pulling speed of the casting blank is 3.2-3.6 m/min;
s2, loading the continuous casting billet into a billet heating furnace for heating, wherein the temperature of a heating section is 1100-1180 ℃ and the heating time is 80-120 min;
s3, after the heated square billet is subjected to descaling by high-pressure water, the square billet enters a high-rigidity short-stress continuous rolling unit to be rolled into a threaded reinforcing steel bar with the diameter of phi 28 mm-phi 40mm, the rolling is divided into three stages of initial rolling, intermediate rolling and finish rolling, wherein the finish rolling temperature is 950-1000 ℃, the reinforcing steel bar after finish rolling is subjected to water cooling, then the reinforcing steel bar enters a cooling bed to be subjected to air cooling, and the temperature of the reinforcing steel bar entering the cooling bed is 900-950 ℃.
4. A method for producing a high toughness weldable steel according to claim 3, wherein the square billet in step S1 has a cross-sectional dimension of 150mm x 150mm to 170mm x 170mm.
5. A method of producing a high toughness weldable steel according to claim 3, comprising the steps of:
s1, smelting molten iron by a converter, refining by a ladle furnace, and pouring into a continuous casting tundish and a crystallizer to form square billets with the cross sections of 150mm multiplied by 150mm to 170mm multiplied by 170 mm; the molten steel temperature of the continuous casting tundish is 1536 ℃, and the cooling water flow of the crystallizer is 2250L/min; the temperature of the casting blank after being cooled by water spraying is 995 ℃ and the drawing speed of the casting blank is 3.3m/min;
s2, loading the continuous casting billet into a billet heating furnace for heating, wherein the temperature of a heating section is 1150 ℃, and the heating time is 110min;
s3, after the heated square billet is subjected to descaling by high-pressure water, the square billet enters a high-rigidity short-stress continuous rolling unit to be rolled into a threaded steel bar with the diameter of 28 mm-40 mm, the rolling is divided into three stages of initial rolling, middle rolling and finish rolling, wherein the finish rolling temperature is 980 ℃, the steel bar after finish rolling is subjected to water cooling, then the steel bar enters a cooling bed to be subjected to air cooling, and the temperature of the steel bar entering the cooling bed is 920 ℃.
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