CN115976405B - Large-thickness SM3Cr2Ni1Mo die steel and production method thereof - Google Patents
Large-thickness SM3Cr2Ni1Mo die steel and production method thereof Download PDFInfo
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- CN115976405B CN115976405B CN202211607361.3A CN202211607361A CN115976405B CN 115976405 B CN115976405 B CN 115976405B CN 202211607361 A CN202211607361 A CN 202211607361A CN 115976405 B CN115976405 B CN 115976405B
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 68
- 239000010959 steel Substances 0.000 title claims abstract description 68
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 14
- 238000000034 method Methods 0.000 claims abstract description 40
- 238000005096 rolling process Methods 0.000 claims abstract description 39
- 238000001816 cooling Methods 0.000 claims abstract description 37
- 238000005266 casting Methods 0.000 claims abstract description 34
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 10
- 238000010791 quenching Methods 0.000 claims abstract description 6
- 230000000171 quenching effect Effects 0.000 claims abstract description 6
- 238000005242 forging Methods 0.000 claims abstract description 4
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 4
- 238000010438 heat treatment Methods 0.000 claims description 24
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 23
- 238000007664 blowing Methods 0.000 claims description 23
- 238000005496 tempering Methods 0.000 claims description 21
- 238000001514 detection method Methods 0.000 claims description 16
- 238000010079 rubber tapping Methods 0.000 claims description 16
- 238000007670 refining Methods 0.000 claims description 15
- 238000004140 cleaning Methods 0.000 claims description 12
- 238000004321 preservation Methods 0.000 claims description 12
- 238000010583 slow cooling Methods 0.000 claims description 12
- 229910052742 iron Inorganic materials 0.000 claims description 11
- 238000004512 die casting Methods 0.000 claims description 9
- 238000001125 extrusion Methods 0.000 claims description 9
- 238000007600 charging Methods 0.000 claims description 6
- 238000007689 inspection Methods 0.000 claims description 5
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- 230000000630 rising effect Effects 0.000 claims description 4
- 239000000126 substance Substances 0.000 claims description 4
- 238000007872 degassing Methods 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 238000011009 performance qualification Methods 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims description 2
- 229910052750 molybdenum Inorganic materials 0.000 claims description 2
- 229910052799 carbon Inorganic materials 0.000 abstract description 9
- 230000007547 defect Effects 0.000 abstract description 7
- 238000005204 segregation Methods 0.000 abstract description 5
- 229910045601 alloy Inorganic materials 0.000 abstract description 3
- 239000000956 alloy Substances 0.000 abstract description 3
- 229910052804 chromium Inorganic materials 0.000 abstract description 2
- 238000007711 solidification Methods 0.000 abstract description 2
- 230000008023 solidification Effects 0.000 abstract description 2
- 239000002893 slag Substances 0.000 description 25
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 24
- 229910052786 argon Inorganic materials 0.000 description 12
- 230000000694 effects Effects 0.000 description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 5
- 241000209094 Oryza Species 0.000 description 4
- 235000007164 Oryza sativa Nutrition 0.000 description 4
- BYFGZMCJNACEKR-UHFFFAOYSA-N aluminium(i) oxide Chemical compound [Al]O[Al] BYFGZMCJNACEKR-UHFFFAOYSA-N 0.000 description 4
- 230000000903 blocking effect Effects 0.000 description 4
- 239000010903 husk Substances 0.000 description 4
- 235000009566 rice Nutrition 0.000 description 4
- 238000003723 Smelting Methods 0.000 description 3
- 239000005997 Calcium carbide Substances 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 2
- 229910000604 Ferrochrome Inorganic materials 0.000 description 2
- 229910000616 Ferromanganese Inorganic materials 0.000 description 2
- 229910001309 Ferromolybdenum Inorganic materials 0.000 description 2
- 229910001200 Ferrotitanium Inorganic materials 0.000 description 2
- 235000011941 Tilia x europaea Nutrition 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 238000007373 indentation Methods 0.000 description 2
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 description 2
- 239000004571 lime Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000011819 refractory material Substances 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 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 2
- 229910000914 Mn alloy Inorganic materials 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 238000005187 foaming Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000001259 photo etching Methods 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 238000007781 pre-processing Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000009849 vacuum degassing Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/58—Roll-force control; Roll-gap control
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
- B22D27/04—Influencing the temperature of the metal, e.g. by heating or cooling the mould
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D37/00—Controlling or regulating the pouring of molten metal from a casting melt-holding vessel
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D7/00—Casting ingots, e.g. from ferrous metals
- B22D7/06—Ingot moulds or their manufacture
-
- 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
- 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
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
- C22C33/06—Making ferrous alloys by melting using master 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
- C22C38/02—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
- C22C38/04—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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
-
- 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
- C22C38/50—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
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
- 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 discloses a method for producing SM3Cr2Ni1Mo with the thickness of 250-280mm by adopting slab ingot rolling, which comprises the following C：0.35-0.40％,Si：0.20-0.40％,Mn：0.85-0.95,P：≤0.015,S：≤0.003,Cr1.80-1.95％,Mo0.30-0.35％,Ni0.85-0.95％,B0.00080-0.0020％,Ti0.030-0.050％, steps of adopting liquidus line +40-50 ℃ to carry out water-cooling ingot mold casting process control and rolling and cooling control to replace forging and quenching processes, thereby ensuring that a rolled steel plate meets the first-level requirements of forge pieces GB/T2970-2016. According to the invention, by combining and collocating the basic elements such as C, mn, si, P, S, als and the alloy elements such as Cr, mo, ni, B, ti, under the micro B condition, the hardenability of the steel plate is improved, so that the core hardness is improved. By adopting water-cooling ingot casting and water quantity control, the solidification speed of molten steel is accelerated, the defects of loosening, segregation and the like are reduced, and meanwhile, the component deviation of the head part and the tail part of the steel plate is reduced. The loose and segregation defects of the steel plate core structure are further eliminated by rolling under high pressure.
Description
Technical Field
The invention belongs to the field of medium plate production, and particularly relates to large-thickness SM3Cr2Ni1Mo die steel and a production method thereof.
Background
SM3Cr2Ni1Mo is one of the common steel types for plastic die steel, and because the steel is subjected to pre-hardening treatment, the material quality is uniform, the cleanliness is high, the steel has excellent polishing performance and photoetching performance, the application is relatively wide, but the steel has high alloy content, a large-thickness steel plate adopts a forging piece to match with a quenching and tempering process so as to meet the pre-hardening requirement, the process has high production cost, and meanwhile, the quenching adopted has cracking risk and relatively high production difficulty.
Disclosure of Invention
In order to solve the technical defects, the invention aims to provide the SM3Cr2Ni1Mo die steel with large thickness, which can obviously reduce the production of finished products compared with the traditional process, has mature heat treatment process and is not easy to crack.
Another object of the present invention is to provide a method for producing a large-thickness SM3Cr2Ni1Mo mold steel.
In order to achieve the above purpose, the invention adopts the following technical scheme: a large-thickness SM3Cr2Ni1Mo die steel, the thickness of the steel plate is 250-280mm, and the steel plate comprises the following chemical components in percentage by mass (unit, wt%) ,C：0.35-0.40％、Si：0.20-0.40％、Mn：0.85-0.95、P：≤0.015、S：≤0.003、Cr：1.80-1.95％、Mo：0.30-0.35％、Ni：0.85-0.95％、B：0.00080-0.0020％、Ti：0.030-0.050％.
Compared with the standard components, the chemical components are added with B and Ti, wherein B has the effect of increasing hardenability, and Ti has the effect of fixing N.
The production method of the steel plate comprises the following steps: blast furnace molten iron, molten iron pretreatment, top and bottom combined blowing converter, LF refining, VD degassing, water-cooling die casting, slow cooling, cleaning, charging and heating, dephosphorization, controlled rolling and controlled cooling, air cooling, high-temperature tempering, slow cooling, flaw detection, sawing, hardness detection, performance qualification, external inspection, warehousing and the like, and finally ensuring that the steel plate is qualified and warehoused, wherein the method comprises the following steps of:
1) Blast furnace molten iron- & gt molten iron pretreatment is carried out according to a normal procedure;
2) The top-bottom combined blown converter is subjected to carbon drawing to reach 0.09% at the end point, and tapping P is less than or equal to 0.012%; the point blowing times are 1 time in the process, the molten steel is not peroxidized, a slag blocking cone is adopted in the tapping process, slag blocking is successful in the tapping process, and slag is not discharged in the tapping process;
3) Adding an aluminum block for deoxidization in the early stage of the tapping process, and adding an aluminum wire for strong deoxidization of molten steel after tapping;
4) 900-1200Kg of lime is added in total in LF refining, 80-130Kg of alumina balls is added in total, 60-100Kg of calcium carbide is added in total, 80-100Kg of aluminum particles is added in total for slagging, slag is white slag or ash white slag after one heating is required to be refined, the smelting final slag is white slag which has good fluidity and foam slag condition, the holding time of the white slag is more than or equal to 35min, 2.0-2.2Kg/t of carbon powder is added in one heating process, the C content is controlled to be rolled at the lower limit, two heating and three heating are added in small quantity to meet the C content requirement, high-carbon ferromanganese, high-carbon ferrochrome, ferromolybdenum and nickel plates are mainly added in two heating, three heating can be added according to two heating components, the adjustment times of Als components in the whole LF refining process are controlled to be less than 2 times, single sampling Als is controlled to be more than 0.030%, the total refining time is required to be controlled to be 60-70min, and the final slag components are: 50-58% of CaO, 28-15% of SiO, 323-30% of Al2O, 5-8% of MgO, less than or equal to 0.8% of FeO and 3-8% of R; adding ferrotitanium after refining;
5) The vacuum refining requires that the vacuum degree in the tank is controlled to be less than or equal to 35Pa, the VD pressure maintaining time is longer than 18min, the argon flow is controlled in the pressure maintaining process, the argon blowing intensity is controlled to be 400-600L/min, the tumbling effect is enhanced, and the H value is controlled to be less than 1.0 ppm; after vacuum breaking, VD is carried out continuously, for example, argon blowing is carried out, and B iron is added according to the ratio of 0.1-0.13 Kg/t.
6) Water-cooling die casting: controlling the soft blowing time before pouring after the steel ladle reaches die casting, and controlling the soft blowing time: controlling argon flow after molten steel reaches die casting, adopting a soft blowing process, controlling the soft blowing flow to be 20-30NL/min, controlling the soft blowing time to be not lower than 10min, stopping blowing argon after the temperature is reduced to 1535-1540 ℃, standing for 5-8min, and pouring, wherein the purpose of blowing argon is to ensure that inclusions float up fully; the casting adopts liquidus +40-50deg.C to perform water-cooled ingot mold casting process control and controlled rolling and controlled cooling to replace forging and quenching processes, the casting temperature adopts liquidus +40-50deg.C to perform water-cooled ingot mold casting, 3/5 of full flow is adopted to start casting when casting is started, full flow casting is adopted until the riser part is cast when casting is started for 5S, 4/5 of full flow is adopted until the riser is fully cast when 300mm from the riser, and the body casting time is controlled at 18min, wherein, in addition, the riser casting time is controlled at 8min when molten steel enters the riser; after pouring, 150-200kg of carbonized rice husk is added for heat preservation, and 100kg of carbonized rice husk is added for a second time after half an hour to improve the heat preservation effect of the riser;
7) And (5) ingot discharging and cleaning: removing an ingot from an ingot mould, directly transferring to a slow cooling pit to release internal stress of a steel ingot, and after slow cooling for 24 hours, starting cleaning, wherein the steel ingot cleaning temperature is 350-360 ℃, so that the cleaning of harmful defects such as cracks, pits, indentations, riser flash, residual refractory materials, riser line folding and the like on the surface of a steel ingot body is thorough, and four edges and corners of the steel ingot are required to be cleaned smoothly;
8) Heating before rolling: the temperature rising speed is less than 50 ℃/h below 700 ℃, the heat preservation temperature is 1220+/-20 ℃, and the heat preservation time is 1.1-1.5 min/mm; before tapping, the temperature of the steel ingot body needs to be measured and is not lower than 1200 ℃; then dephosphorizing;
9) And (3) controlled cooling and rolling: when the ingot is rolled, the surface temperature of the ingot is over 980 ℃, the rough rolling adopts differential temperature rolling, high-pressure water is applied once for each rolling, the rolling is stopped for a single pass, the rolling is stopped when the thickness is up to 350mm, cold steel is carried out, the rolling is started for a second time when the temperature is reduced to 800-850 ℃, and simultaneously, vertical roller edge extrusion is carried out, the single pass of the vertical roller edge extrusion is required to be controlled to be 10mm, and the repeated edge extrusion is required, so that the aim of delivering goods in a uniform edge is fulfilled; after rolling, entering a laminar cooling device, controlling the reddening temperature to be 550-600 ℃, and then hanging to a cooling bed for cooling;
10 Tempering: when the temperature is reduced to 250-300 ℃, charging and tempering, wherein the tempering temperature is controlled to 600+/-10 ℃, and the tempering coefficient T=4 min/mm; stacking and slowly cooling the steel plates from the tempering furnace until the temperature is reduced to normal temperature;
11 Flaw detection and cutting dimensions: unstacking and flaw detection, sawing and hardness detection.
According to the invention, by combining and collocating the basic elements such as C, mn, si, P, S, als and the alloy elements such as Cr, mo, ni, B, ti, under the micro B condition, the hardenability of the steel plate is improved, so that the core hardness is improved. By adopting water-cooling ingot casting and water quantity control, the solidification speed of molten steel is accelerated, the defects of loosening, segregation and the like are reduced, and meanwhile, the component deviation of the head part and the tail part of the steel plate is reduced. The loose and segregation defects of the steel plate core structure are further eliminated by rolling under high pressure. The purposes of quenching are achieved by rolling and cooling control, the cost is effectively reduced, the furnace is charged at low temperature, the heating is slow, and the tempering and stacking cooling are realized, so that the stress of the whole steel plate is reduced, and the hardness uniformity is improved.
Detailed Description
For a better understanding of the present application, the following examples are set forth to further illustrate the application, but are not to be construed as limiting the application. In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present application. It will be apparent, however, to one skilled in the art that the application may be practiced without one or more of these details.
Examples
The production of 280mm thick SM3Cr2Ni1Mo die steel comprises the following chemical components in percentage by mass (unit, wt%):
C：0.35-0.40％,Si：0.20-0.40％,Mn：0.85-0.95,P：≤0.015,S：≤0.003,Cr1.80-1.95％,Mo0.30-0.35％,Ni0.85-0.95％,B0.00080-0.0020％,Ti0.030-0.050％, The others are residual elements.
The production process of the die steel comprises the following steps: the method comprises the steps of self-producing molten iron (strictly controlling the content of residual elements), preprocessing molten iron, carrying out top-bottom combined blowing converter, LF refining, VD degassing, water-cooling die casting, slow cooling, cleaning, charging and heating, controlling rolling, laminar cooling, air cooling, high-temperature tempering, slow cooling, flaw detection, sawing, hardness detection, performance qualification, external inspection and warehousing. The process flow is characterized by controlling residual elements, pretreating molten iron, adopting a converter process, adopting an LF process, adopting a VD vacuum degassing process, adopting a water-cooling die casting process, adopting a slow cooling process after ingot removal, adopting a high-temperature cleaning process, adopting a heating process, adopting a rolling process, adopting a cold control process, adopting a low-temperature charging tempering process and adopting a slow cooling process after tempering.
Through KR molten iron pretreatment, slag layer thickness is controlled below 10mm through slag skimming, and S content after S removal is 0.008%.
Smelting in a converter: by increasing the flow of bottom blowing argon, the stirring effect is strong, the carbon pulling is uniform at the end point, double slag operation is adopted, the carbon is tapped by 0.09%, and the tapping P is less than or equal to 0.012%; the number of times of point blowing is 1, molten steel is not peroxidized, a slag blocking cone is adopted in the tapping process, slag blocking is successful in the tapping process, and slag is not discharged in the tapping process.
Adding a tapping deoxidizer: 100kg of Si-Al-Ca-Ba is added for deoxidization in the tapping process, si-Mn alloy is added for compounding ingredients, and 200m of aluminum wire is added for strong deoxidization after tapping.
Refining in an LF furnace: the LF refining slag making adopts 1100Kg lime, 120Kg alumina balls, 70Kg calcium carbide and 60Kg aluminum particles for slag making, the slag after heating is in off-white, the smelting final slag is white slag with good fluidity and foaming slag condition, the subsequent white slag holding time is 38min, 2.0-2.2Kg/t carbon powder is added in the heating process, the C content is controlled to be rolled at the lower limit, the secondary heating and the tertiary heating are supplemented in a small amount to meet the C content requirement, the secondary heating is mainly added with high-carbon ferromanganese, high-carbon ferrochrome, ferromolybdenum and nickel plates, the tertiary heating can be supplemented according to the secondary heating components, the adjustment times of Als components in the LF whole refining process are controlled to be 2 times, the tertiary sampling Als is controlled to be more than 0.030%, the total refining time is required to be controlled to be 68min, and the final slag components are as follows: 52% of CaO, 211% of SiO, 325% of Al2O, 6% of MgO, 0.72% of FeO and 4.8% of R; adding ferrotitanium after refining.
And (3) VD vacuum refining: the VD vacuum refining requires that the limit vacuum degree in the tank is controlled to be 15-30Pa, the VD pressure maintaining time is controlled to be 19min, the pressure maintaining process is operated according to a large argon blowing process, the argon blowing intensity is controlled to be 500-600L/min, the turning effect is enhanced, and the H value is controlled to be 0.78ppm; after vacuum breaking, VD is carried out continuously, for example, argon blowing is carried out, and B iron is added according to the ratio of 0.1-0.13 Kg/t.
Soft blowing time control: and controlling the flow of argon after the molten steel reaches die casting, adopting a soft blowing process, controlling the soft blowing flow to be 25NL/min, controlling the soft blowing time to be 12min, and stopping blowing argon after the temperature is reduced to 1538 ℃.
Confirming the temperature before casting: measuring the temperature of 3 rods, wherein the measured temperature is 1536 ℃, 1538 ℃, 1536 ℃, the error between 3 rods is within 2 ℃, and then standing for 7min for pouring.
The casting process comprises the following steps: the ingot casting with 40t is adopted, the thickness of the ingot is 850mm at the upper opening, the thickness of the ingot is 820mm at the lower opening, the left taper and the right taper are controlled to be 30+/-5 mm, and the hot heat preservation cap is adopted to perform the sitting-up preparation casting in advance. And (3) during casting, adopting full-flow 3/5 to start casting, adopting full-flow casting until the dead head is cast when the casting is started for 5S, adopting full-flow 4/5 casting until the dead head is full when the distance from the dead head is 300mm, controlling the casting time of the body at 18min, and controlling the dead head time at 8min.
Controlling the water cooling die water quantity: with the apparatus of patent number [ patent number 200910064854.5 ], water control: the water quantity in the early stage is controlled to be 360m < 3 >/h, and the water quantity is not reduced in the process due to strong crack sensitivity of the steel grade, and the steel grade is demoulded after 8 hours.
And (3) heat preservation measures: after casting, 150-200kg of carbonized rice husk is added for heat preservation, and 100kg of carbonized rice husk is added for a second time after half an hour to improve the heat preservation effect of the riser.
Slowly cooling and cleaning: after the ingot is demolded, the ingot is directly transferred to a slow cooling pit to release the internal stress of the steel ingot, the steel ingot is cleaned after slow cooling for 24 hours, the steel ingot cleaning temperature is 350-360 ℃, and the cleaning of harmful defects such as cracks, pits, indentations, riser flash, residual refractory materials, riser line folding and the like on the surface of the steel ingot body is thorough, and meanwhile, the cleaning of four edges and corners of the steel ingot is required to be smooth.
Heating the cast ingot: the temperature rising speed below 700 ℃ is less than 50 ℃/h, the heat preservation temperature is 1220+/-20 ℃, and the heat preservation time is 1.1-1.5 min/mm. Before tapping, the temperature of the steel ingot body needs to be measured and is not lower than 1200 ℃.
Rolling: the surface temperature of a spindle during initial rolling is higher than 980 ℃, rough rolling adopts differential temperature rolling, high-pressure water is pumped once for each rolling, the rolling is stopped for a single time, the rolling is stopped when the thickness is up to 350mm, cold steel is cooled, secondary initial rolling is performed when the temperature is reduced to 800-850 ℃, and vertical rod edge extrusion is performed simultaneously, the single time of vertical rod edge extrusion is required to be controlled at 10mm, multiple times of edge extrusion are required, and the aim of delivering goods in an aligned way is fulfilled; after the secondary rolling is finished, the mixture enters a laminar cooling device, the reddening temperature is controlled to be 550-600 ℃, and then the mixture is hung to a cooling bed for cooling.
Tempering and heating: when the temperature of the steel plate is reduced to 250-300 ℃, charging and tempering, wherein the tempering temperature is controlled to 600+/-10 ℃, and the tempering coefficient T=4 min/mm; and (3) stacking and slowly cooling the steel plates from the tempering furnace, and after the temperature is reduced to normal temperature, unstacking and flaw detection, sawing and hardness detection are carried out.
The mass of the SM3Cr2Ni1Mo die steel with the thickness of 280mm in the embodiment is as follows:
Surface hardness detection
Section hardness detection
Inclusion detection
The inclusion is rated according to GB/T10561 microscopic examination method of measuring standard rating diagram for nonmetallic inclusion content in steel, and the detection results are shown in the following table:
Nondestructive flaw detection: and carrying out nondestructive inspection according to GB/T2970-2016 ultrasonic inspection method for thick steel plates, and combining the steps. According to the test results, the components of different parts of the SM3Cr2Ni1Mo die steel with the thickness of 280mm are uniform, the structure is compact, the segregation is slight, and the components and the impurity content meet the technical requirements of the SM3Cr2Ni1Mo die steel. The detected steel plate has uniform surface and thickness section hardness, and can meet the steel requirement for plastic molds.
Claims (1)
1. A production method of large-thickness SM3Cr2Ni1Mo die steel is characterized by comprising the following steps: the thickness of the steel plate is 250-280mm, and the steel plate comprises the following chemical components in percentage by mass ,C：0.35-0.40％、Si：0.20-0.40％、Mn：0.85-0.95、P：≤0.015、S：≤0.003、Cr：1.80-1.95％、Mo：0.30-0.35％、Ni：0.85-0.95％、B：0.00080-0.0020％、Ti：0.030-0.050％;
The production method of the steel plate comprises the following steps: blast furnace molten iron, molten iron pretreatment, top and bottom combined blowing converter, LF refining, VD degassing, water-cooling die casting, slow cooling, cleaning, charging and heating, descaling, rolling and cooling control, air cooling, high-temperature tempering, slow cooling, flaw detection, sawing, hardness detection, performance qualification, external inspection and warehousing, and finally ensuring that the steel plate is qualified and warehoused, wherein the method comprises the following steps of:
Water-cooling die casting: the casting adopts liquidus +40-50deg.C to perform water-cooled ingot mold casting process control and controlled rolling and controlled cooling to replace forging and quenching processes, the casting temperature adopts liquidus +40-50deg.C to perform water-cooled ingot mold casting, 3/5 of full flow is adopted to start casting when casting is started, full flow casting is adopted until the riser part is cast when casting is started for 5s, 4/5 of full flow is adopted until the riser is fully cast when 300mm from the riser, and the body casting time is controlled at 18min, wherein, in addition, the riser casting time is controlled at 8min when molten steel enters the riser;
heating before rolling: the temperature rising speed below 700 ℃ is less than 50 ℃/h, after 700 ℃, the temperature rising speed is accelerated, the heat preservation temperature is 1220+/-20 ℃, and the heat preservation time is 1.1-1.5 min/mm; before tapping, measuring the temperature of a steel ingot body, and then descaling, wherein the temperature of the steel ingot body is not lower than 1200 ℃;
Rolling and cooling control: the cogging rolling temperature is >980 ℃, the rough rolling adopts differential temperature rolling, high-pressure water is applied once every rolling, the single-pass rolling reduction is 50-60mm, rolling is stopped when the thickness is up to 350mm, cooling is carried out, secondary rolling is started when the temperature is reduced to 800-850 ℃, and edge extrusion of a vertical roller is carried out, the single-pass edge extrusion of the vertical roller is required to be controlled at 10mm, multiple edge extrusion is required, and the aim of delivering goods in a uniform edge is achieved; after secondary rolling is finished, entering laminar cooling equipment, controlling the reddening temperature to be 550-600 ℃, and then hanging to a cooling bed for cooling;
Tempering: when the temperature is reduced to 250-300 ℃, loading the mixture into a tempering furnace, controlling the tempering temperature to 600+/-10 ℃ and controlling the tempering coefficient T=4 min/mm; and (5) stacking and slowly cooling the steel plates after discharging until the temperature is reduced to normal temperature.
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| PCT/CN2023/123719 WO2024125055A1 (en) | 2022-12-14 | 2023-10-10 | Large-thickness sm3cr2ni1mo mold steel and production method therefor |
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