CN113106351A - Ultralow-temperature 9Ni steel and preparation process thereof - Google Patents
Ultralow-temperature 9Ni steel and preparation process thereof Download PDFInfo
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- CN113106351A CN113106351A CN202110421448.0A CN202110421448A CN113106351A CN 113106351 A CN113106351 A CN 113106351A CN 202110421448 A CN202110421448 A CN 202110421448A CN 113106351 A CN113106351 A CN 113106351A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 57
- 239000010959 steel Substances 0.000 title claims abstract description 57
- 238000002360 preparation method Methods 0.000 title claims abstract description 10
- 238000010438 heat treatment Methods 0.000 claims abstract description 44
- 238000005242 forging Methods 0.000 claims abstract description 30
- 238000010791 quenching Methods 0.000 claims abstract description 25
- 230000000171 quenching effect Effects 0.000 claims abstract description 25
- 238000000034 method Methods 0.000 claims abstract description 23
- 230000008569 process Effects 0.000 claims abstract description 23
- 238000001816 cooling Methods 0.000 claims abstract description 14
- 238000005496 tempering Methods 0.000 claims abstract description 14
- 239000000126 substance Substances 0.000 claims abstract description 8
- 239000012535 impurity Substances 0.000 claims abstract description 5
- 238000004321 preservation Methods 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- 239000007921 spray Substances 0.000 claims description 8
- 238000005520 cutting process Methods 0.000 claims description 7
- 238000005507 spraying Methods 0.000 claims description 7
- 239000002689 soil Substances 0.000 claims 1
- 229910001566 austenite Inorganic materials 0.000 description 17
- 239000010949 copper Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 239000011572 manganese Substances 0.000 description 6
- 229910000734 martensite Inorganic materials 0.000 description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 239000013078 crystal Substances 0.000 description 5
- 229910052717 sulfur Inorganic materials 0.000 description 5
- 239000011593 sulfur Substances 0.000 description 5
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 229910052748 manganese Inorganic materials 0.000 description 4
- 238000005728 strengthening Methods 0.000 description 4
- 238000003466 welding Methods 0.000 description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 229910052698 phosphorus Inorganic materials 0.000 description 3
- 239000011574 phosphorus Substances 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 239000006104 solid solution Substances 0.000 description 3
- 230000006378 damage Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- FBPFZTCFMRRESA-JGWLITMVSA-N D-glucitol Chemical compound OC[C@H](O)[C@@H](O)[C@H](O)[C@H](O)CO FBPFZTCFMRRESA-JGWLITMVSA-N 0.000 description 1
- 229910017112 Fe—C Inorganic materials 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000009863 impact test Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000010587 phase diagram Methods 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910002066 substitutional alloy Inorganic materials 0.000 description 1
- 238000004154 testing of material Methods 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
-
- 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
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/28—Normalising
-
- 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
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
-
- 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
-
- 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
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
-
- 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
- C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
The invention relates to the technical field of ultralow-temperature 9Ni steel preparation, and discloses ultralow-temperature 9Ni steel which comprises the following chemical components in percentage by mass: 0.05-0.06% of C, 0.05-0.06% of Si, 0.55-0.59% of Mn, less than or equal to 0.005% of P, less than or equal to 0.001% of S, 8.5-9.5% of Ni, 0.02-0.05% of Al, 0.01-1.0% of Cu, and the balance of Fe and impurity elements. The invention also discloses a preparation process of the ultralow-temperature 9Ni steel, which comprises the following steps: preparing a 9Ni steel large-section forging; step two, carrying out low-temperature impact toughness heat treatment on the 9Ni steel large-section forging, specifically comprising the following steps: the heat treatment process of quenching-two-phase zone sub-temperature quenching-tempering-cooling is adopted, wherein, quenching is carried out at 830-900 ℃, sub-temperature quenching is carried out at 635-655 ℃, and tempering is carried out at 560-600 ℃. The invention solves the technical problem of insufficient ultralow-temperature impact toughness of the 9Ni steel in the prior art.
Description
Disclosure of Invention
Technical problem to be solved
Aiming at the defects of the prior art, the invention provides an ultralow temperature 9Ni steel and a preparation process thereof, aiming at solving the technical problem of insufficient ultralow temperature impact toughness of the 9Ni steel in the prior art.
(II) technical scheme
In order to achieve the purpose, the invention provides the following technical scheme:
the ultralow-temperature 9Ni steel comprises the following chemical components in percentage by mass: 0.05-0.06% of C, 0.05-0.06% of Si, 0.55-0.59% of Mn, less than or equal to 0.005% of P, less than or equal to 0.001% of S, 8.5-9.5% of Ni, 0.02-0.05% of Al, 0.01-1.0% of Cu, and the balance of Fe and impurity elements.
A preparation process of ultralow-temperature 9Ni steel comprises the following steps:
preparing a 9Ni steel large-section forging;
step two, carrying out low-temperature impact toughness heat treatment on the 9Ni steel large-section forging, specifically comprising the following steps: the heat treatment process of quenching-two-phase zone sub-temperature quenching-tempering-cooling is adopted, wherein, quenching is carried out at 830-900 ℃, sub-temperature quenching is carried out at 635-655 ℃, and tempering is carried out at 560-600 ℃.
Further, the specific process of the large-section forging process of the 9Ni steel is as follows:
step S1, selecting a blank, and cutting off a dead head and a water gap, wherein the cutting amount is 5-20%;
step S2, loading the blanks into a furnace, wherein gaps are reserved among the blanks, and the gap distance is 4-20 mm;
step S3, heating the blank in the furnace for the first time at 1100-1300 ℃, then carrying out heat preservation treatment for the first time at 1100-1300 ℃ for 20-30 minutes, and then carrying out upsetting and drawing, wherein the forging ratio is 4-5;
step S4, carrying out secondary heating on the large-section forge piece in the furnace, wherein the secondary heating temperature is 1000-1100 ℃, then carrying out secondary heat preservation treatment, the secondary heat preservation temperature is 1000-1100 ℃, the secondary heat preservation time is 40-60 minutes, then carrying out upsetting and drawing, and the forging ratio is 3-4;
step S5, heating the large-section forge piece in the furnace for three times at the temperature of 600-850 ℃, then carrying out heat preservation treatment for three times at the temperature of 600-850 ℃, keeping the temperature for three times for 1-2 hours, and then carrying out upsetting and drawing, wherein the forging ratio is 1.8-3.1;
in step S6, the large-section workpiece upset and drawn out in step S5 is immediately subjected to a normalizing process.
Further, the specific process of the heat treatment process is as follows:
step S1, quenching for the first time, feeding in a cold furnace at room temperature or in a warm furnace at 220 +/-5 ℃, and preserving heat for 8-10 hours for warm furnace preheating; heating to 400-450 ℃ at a speed of 15-30 ℃/h, and keeping the temperature for 10-15 h; continuously heating to 600-650 ℃ at the heating rate of 15-20 ℃/h, and keeping the temperature for 10-15 h; then the temperature of the high-temperature section is increased to 830-900 ℃ at the heating rate of 50 ℃/h;
step S2, performing secondary sub-temperature quenching, wherein the temperature is reduced to 650-Ac 790 ℃, and performing sub-temperature quenching at a lower Acl-Ac3 temperature;
step S3, tempering, wherein the tempering temperature is 560-;
and step S4, cooling for 20 minutes, vertically placing the workpiece in a vertical spray quenching device, and spraying water for cooling for 25-30 hours.
(III) advantageous technical effects
Compared with the prior art, the invention has the following beneficial technical effects:
1. aiming at the defect of insufficient ultralow-temperature impact toughness of 9Ni steel in the prior art, the structure form is changed through a heat treatment process, so that inverted austenite is separated out in a flaky manner among martensite lath crystals and is uniformly distributed, the thermal stability of the inverted austenite is further improved, the grain boundary and a matrix are toughened, and the ultralow-temperature impact toughness of the 9Ni steel is obviously improved.
2. The Cu element is added to the chemical components, so that the stability of the residual austenite is improved, the strength of the steel plate is improved, a large amount of rare and precious molybdenum elements are avoided, and the strength of the steel plate is further improved.
3. According to the invention, by cutting off the dead head and the water gap and carrying out the heating and heat preservation process for 3 times, the influence on the product quality caused by rapid growth of crystal grains due to overhigh finish forging temperature and over-small final deformation of the product is avoided, no crack is generated on the surface and inside of the large-section forging, the chemical components of the forging are uniform, and the structure is stable.
4. The invention adopts the variable frequency pump to control the flow of cooling water, can greatly reduce the water and electricity consumption in the heat treatment process, saves the quenching heat treatment cost, breaks through the constant flow process during spray quenching cooling, and realizes energy conservation and emission reduction.
5. The heating process adopts the preheating of the warm furnace, the intermediate holding of the two times and the rapid temperature rise in the high-temperature section, thereby effectively reducing the temperature difference of the core wall in the heating process and avoiding the overlarge thermal stress in the workpiece.
6. According to the invention, three steps of heating, cooling and tempering are carried out, so that the temperature difference of QL, QQ and NN in QLT, QQT and NNT is enlarged, inverted austenite is separated out in a sheet shape among martensite lath crystals and is uniformly distributed, and the thermal stability of the inverted austenite is further improved, so that the crystal boundary and the matrix are toughened, the ultralow-temperature impact toughness of the 9Ni steel can be obviously improved, and the strength is ensured.
7. The impact energy of the large-section 9Ni steel forging prepared by the invention is more than 80J in a cryogenic environment at the temperature of 196 ℃ below zero after the large-section forging is subjected to heat treatment of a heat treatment process.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The improved 9Ni steel comprises the following chemical components in percentage by mass: 0.05-0.06% of C, 0.05-0.06% of Si, 0.55-0.59% of Mn, less than or equal to 0.005% of P, less than or equal to 0.001% of S, 8.5-9.5% of Ni, 0.02-0.05% of Al, 0.01-1.0% of Cu, and the balance of Fe and impurity elements;
the ultrahigh-strength 9Ni steel applied to the cryogenic environment comprises the following components in percentage by weight:
c: carbon is a strong solid solution strengthening element, can obviously improve the strength of the steel plate, can improve the stability of austenite at the same time, but reduces toughness and plasticity, obviously deteriorates the welding performance of the steel plate, and in the chemical composition design of the ship plate steel, in order to ensure that the steel plate has good welding performance and good low-temperature impact toughness, the carbon content in the steel must be reduced and controlled at the middle lower limit;
si: silicon plays a role in solid solution strengthening in steel, improves the strength of the steel plate, can improve the activity of carbon, promotes ferrite formation, and diffuses the carbon into the residual austenite, so that the silicon in 9Ni steel contributes to the formation and stability of residual martensite and inhibits the formation of cementite, but the low-temperature toughness and welding performance of the steel plate are seriously damaged due to the over-high content of silicon;
mn: manganese is a substitutional alloy element, the strength of the steel is improved by solid solution strengthening and grain refining, meanwhile, the manganese can expand a gamma phase region in an Fe-C phase diagram to play a role in stabilizing austenite, but when the content of the manganese is too high, a segregation structure is easy to form and is harmful to the performance of the steel, and in addition, the manganese reduces the activity of carbon in the austenite and promotes the formation of carbides;
s: sulfur is a harmful inclusion forming element in steel, is often distributed along the rolling direction in the form of inclusions such as MnS and the like, and is used for reducing the sulfur content because the sulfur destroys the continuity of the steel, obviously reduces the ductility and the toughness, aggravates the anisotropy and damages the weldability, and the influence degree is aggravated along with the increase of the sulfur content, so the sulfur content is generally controlled below 0.002 percent in Japan 9Ni steel;
p: phosphorus is an important grain boundary segregation element in steel and has great harm effect on low-temperature impact toughness and welding performance, the phosphorus content of Japanese 9Ni steel is generally controlled below 0.005%, and the phosphorus content of 9Ni steel produced by Nissian iron and JFE is generally controlled below 0.002%;
ni: nickel is the most main alloy element in 9Ni steel and is also an austenite forming element, the austenite region can be enlarged, the Ar3 temperature is reduced, the nickel element is diffused and enriched in the austenite during tempering, and the retained austenite can be stabilized after cooling, so that the impact toughness under a cryogenic environment is greatly improved;
cu: the copper element can increase the strength of the steel plate and improve the corrosion resistance of the steel plate, fine and dispersed Cu can be precipitated during proper tempering treatment, the precipitation strengthening effect is achieved, and the stability of the retained austenite can be improved by the Cu;
a preparation process of ultralow-temperature 9Ni steel comprises the following steps:
step one, a forging process of a large section of 9Ni steel, which comprises the following specific steps:
step S1, selecting a blank, and cutting off a dead head and a water gap, wherein the cutting amount is 5-20%;
step S2, loading the blanks into a furnace, wherein gaps are reserved among the blanks, and the gap distance is 4-20 mm;
step S3, heating the blank in the furnace for the first time at 1100-1300 ℃, then carrying out heat preservation treatment for the first time at 1100-1300 ℃ for 20-30 minutes, and then carrying out upsetting and drawing, wherein the forging ratio is 4-5;
step S4, carrying out secondary heating on the large-section forge piece in the furnace, wherein the secondary heating temperature is 1000-1100 ℃, then carrying out secondary heat preservation treatment, the secondary heat preservation temperature is 1000-1100 ℃, the secondary heat preservation time is 40-60 minutes, then carrying out upsetting and drawing, and the forging ratio is 3-4;
step S5, heating the large-section forge piece in the furnace for three times at the temperature of 600-850 ℃, then carrying out heat preservation treatment for three times at the temperature of 600-850 ℃, keeping the temperature for three times for 1-2 hours, then carrying out upsetting and drawing, wherein the forging ratio is 1.8-3.1, and the influence on the product quality caused by rapid growth of crystal grains due to overhigh finish forging temperature and over-small final deformation of the product is avoided;
step S6, immediately normalizing the large-section part subjected to upsetting and drawing in the step S5, eliminating internal stress in the forging process and refining grains;
the surface and the interior of the large-section forging forged by the process have no cracks, and the forging has uniform chemical components and stable structure;
step two, the heat treatment process of the low-temperature impact toughness of the large-section forging of the 9Ni steel adopts a heat treatment process of quenching-two-phase zone sub-temperature quenching-tempering (QLT) -cooling, wherein the heat treatment process comprises the following specific steps of quenching at 830-900 ℃, sub-temperature quenching at 635-655 ℃ and tempering at 560-600 ℃:
step S1, quenching for the first time, feeding in a cold furnace at room temperature or in a warm furnace at 220 +/-5 ℃, and preserving heat for 8-10 hours for warm furnace preheating; heating to 400-450 ℃ at a speed of 15-30 ℃/h, and keeping the temperature for 10-15 h; continuously heating to 600-650 ℃ at the heating rate of 15-20 ℃/h, and keeping the temperature for 10-15 h; then the temperature of the high-temperature section is increased to 830-900 ℃ at the heating rate of 50 ℃/h, so that the tissue is completely austenitized, impurities and second-phase particles are redissolved, and austenite grains are refined;
step S2, performing secondary sub-temperature quenching, wherein the temperature is reduced to 650-790 ℃, and performing sub-temperature quenching at a lower Acl-Ac3 temperature so as to obtain fine ferrite and martensite structures through phase change recrystallization;
step S3, in the tempering stage, the tempering temperature is 560-600 ℃, so that the steel obtains a structure mainly comprising tempered sorbite, the quantity of reversed austenite in the steel is increased through the reverse transformation of martensite, and the reversed austenite is mainly distributed on the lath martensite boundary, so that the structure is more dispersed and uniformly distributed; meanwhile, the precipitation amount of carbide is large and fine and dispersed;
step S4, cooling for 20 minutes, vertically placing the workpiece in a vertical spray quenching device, spraying water for cooling for 25-30 hours, wherein the final cooling time of the water spray is given according to the time when the core part is cooled to be lower than 180 ℃; in the spray quenching process, the water spraying flow is controlled to be reduced in a step-by-step mode according to the spray quenching time, for example, 2700t/h is carried out in the first 30 minutes, 900t/h is carried out in the last 2 hours, and finally water is sprayed according to the minimum spraying amount required by the device; or a shallow thermocouple is adopted to measure the surface temperature in real time, the frequency of the variable frequency pump is controlled according to the reduction rate of the surface temperature, the water spraying amount is continuously reduced from 2700t/h to the minimum flow, and the minimum flow is the larger value of the minimum spraying amount required by the spray quenching device and the minimum rated flow of the variable frequency pump;
testing the impact temperature of the prepared 9Ni steel large-section forging to be-196 ℃ by adopting a low-temperature impact testing machine with the model of JBD-300A, wherein the impact energy is more than 80J in a cryogenic environment at the temperature of-196 ℃;
a universal material testing machine with the model of WE-600 is adopted to test that the yield strength of the prepared 9Ni steel large-section forging is more than or equal to 585MPa, the tensile strength is more than or equal to 690MPa, and the elongation is more than or equal to 22%.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (4)
1. The ultralow-temperature 9Ni steel is characterized by comprising the following chemical components in percentage by mass: 0.05-0.06% of C, 0.05-0.06% of Si, 0.55-0.59% of Mn, less than or equal to 0.005% of P, less than or equal to 0.001% of S, 8.5-9.5% of Ni, 10.02-0.05% of A, 0.01-1.0% of CuO, and the balance of Fe and impurity elements.
2. The preparation process of the ultralow-temperature 9Ni steel is characterized by comprising the following steps of:
preparing a 9Ni steel large-section forging;
step two, carrying out low-temperature impact toughness heat treatment on the 9Ni steel large-section forging, specifically comprising the following steps: the heat treatment process of quenching-two-phase zone sub-temperature quenching-tempering-cooling is adopted, wherein, quenching is carried out at 830-900 ℃, sub-temperature quenching is carried out at 635-655 ℃, and tempering is carried out at 560-600 ℃.
3. The preparation process of the ultralow-temperature 9Ni steel as claimed in claim 2, wherein the 9Ni steel large-section forging process comprises the following specific steps:
step S1, selecting a blank, and cutting off a dead head and a water gap, wherein the cutting amount is 5-20%;
step S2, loading the blanks into a furnace, wherein gaps are reserved among the blanks, and the gap distance is 4-20 mm;
step S3, heating the blank in the furnace for the first time at 1100-1300 ℃, then carrying out heat preservation treatment for the first time at 1100-1300 ℃ for 20-30 minutes, and then carrying out upsetting and drawing, wherein the forging ratio is 4-5;
step S4, carrying out secondary heating on the large-section forge piece in the furnace, wherein the secondary heating temperature is 1000-1100 ℃, then carrying out secondary heat preservation treatment, the secondary heat preservation temperature is 1000-1100 ℃, the secondary heat preservation time is 40-60 minutes, then carrying out upsetting and drawing, and the forging ratio is 3-4;
step S5, heating the large-section forge piece in the furnace for three times at the temperature of 600-850 ℃, then carrying out heat preservation treatment for three times at the temperature of 600-850 ℃, keeping the temperature for three times for 1-2 hours, and then carrying out upsetting and drawing, wherein the forging ratio is 1.8-3.1;
in step S6, the large-section workpiece upset and drawn out in step S5 is immediately subjected to a normalizing process.
4. The preparation process of the ultra-low temperature 9Ni steel as claimed in claim 3, wherein the heat treatment process comprises the following steps:
step S1, quenching for the first time, feeding in a cold furnace at room temperature or feeding in a warm furnace at 5 ℃ of 220 soil, and preserving heat for 8-10h for warm furnace preheating; heating to 400-450 ℃ at a speed of 15-30 ℃/h, and keeping the temperature for 10-15 h; continuously heating to 600-650 ℃ at the heating rate of 15-20 ℃/h, and keeping the temperature for 10-15 h; then the temperature of the high-temperature section is increased to 830-900 ℃ at the heating rate of 50 ℃/h;
step S2, performing secondary subtemperature quenching, wherein the temperature is reduced to 650-790 ℃, and the subtemperature quenching is performed at a lower temperature of Ac1-Ac 3;
step S3, tempering, wherein the tempering temperature is 560-;
and step S4, cooling for 20 minutes, vertically placing the workpiece in a vertical spray quenching device, and spraying water for cooling for 25-30 hours.
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| CN114622073A (en) * | 2022-03-09 | 2022-06-14 | 包头钢铁（集团）有限责任公司 | Method for improving low-temperature impact toughness of boron-containing steel by using sub-temperature quenching |
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| CN114622073B (en) * | 2022-03-09 | 2024-02-23 | 包头钢铁（集团）有限责任公司 | Method for improving low-temperature impact toughness of boron-containing steel by utilizing sub-temperature quenching |
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