CN114438394A - Production process of pre-hardened high-polishing plastic mold steel - Google Patents
Production process of pre-hardened high-polishing plastic mold steel Download PDFInfo
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- CN114438394A CN114438394A CN202210090893.8A CN202210090893A CN114438394A CN 114438394 A CN114438394 A CN 114438394A CN 202210090893 A CN202210090893 A CN 202210090893A CN 114438394 A CN114438394 A CN 114438394A
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- 238000005498 polishing Methods 0.000 title claims abstract description 30
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- 229910001214 P-type tool steel Inorganic materials 0.000 title claims description 22
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 88
- 239000010959 steel Substances 0.000 claims abstract description 88
- 238000010438 heat treatment Methods 0.000 claims abstract description 72
- 238000003723 Smelting Methods 0.000 claims abstract description 62
- 238000005242 forging Methods 0.000 claims abstract description 38
- 238000000034 method Methods 0.000 claims abstract description 25
- 230000008569 process Effects 0.000 claims abstract description 19
- 238000010274 multidirectional forging Methods 0.000 claims abstract description 14
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- 238000007670 refining Methods 0.000 claims description 88
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- 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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/002—Hybrid process, e.g. forging following casting
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- 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
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- 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
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- 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
- C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/16—Remelting metals
- C22B9/18—Electroslag remelting
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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Abstract
The invention relates to a production process of pre-hardened high-polishing plastic mould steel, which mainly comprises the following steps: s1, smelting an electrode blank; s2, electroslag smelting; s3, homogenizing at high temperature; s4, multidirectional forging; s5, performing heat treatment after forging; s6 pre-hard processing. Based on common plastic die steel, the prepared product has excellent purity, texture uniformity and mechanical property by adopting special smelting, forging and heat treatment processes. The die made of the material can better meet the requirements of modern industrial production on high-end dies. The invention also relates to pre-hardened high-polishing plastic die steel, and the prepared plastic die steel has excellent polishing performance, dermatoglyph performance and excellent tissue and hardness uniformity.
Description
Technical Field
The invention relates to die steel and a preparation method thereof, in particular to a production process of pre-hardened high-polishing plastic die steel.
Background
With the development of the plastic industry, the demand for high-quality plastic die steel is increasing, and the high-quality plastic die steel requires that the steel have higher polishing performance (generally, polishing degree requirement is over 12000 #), higher hardenability and hardness uniformity. As die steel produced by domestic iron and steel enterprises still has a larger gap in quality level compared with international enterprises, high-quality plastic die steel depends on import for a long time. For example, 718 of the Swedish UDDEHOLM company, 2311 and 2738 of the Germany SAAARS company, HPM7 of the Hitachi metal company, PDS3 of the Daqiong special steel company and the like are common imported brands in the domestic market, and the price is 2-3 times or even higher than that in the domestic market.
In order to reach the quality level close to that of foreign plastic die steel, forging is not feasible only by smelting steel ingots by an electric furnace, and the die steel is ensured to have excellent polishing and dermatoglyph performances and excellent tissue and hardness uniformity by the procedures of electroslag remelting, high-temperature homogenization, multidimensional forging, normalizing hydrogen diffusion, pre-hardening and the like.
However, each link in the procedures of electroslag remelting, high-temperature homogenization, multidimensional forging, normalizing hydrogen diffusion, pre-hardening and the like must be implemented by adopting excellent equipment and reasonable process parameters; in particular, white spots, uneven hardness and the like can occur when the process control is improper in the heat treatment process after forging of plastic die steel with a large cross section, so that the die material is failed or scrapped, and great economic loss is caused.
Disclosure of Invention
The invention aims to provide a production process of pre-hardened high-polishing plastic die steel, and the prepared plastic die steel has excellent polishing performance and dermatoglyph performance and excellent tissue and hardness uniformity.
In order to achieve the purpose of the invention, the production process of the pre-hardened high-polishing plastic mould steel mainly comprises the following steps:
s1, smelting an electrode blank:
batching scrap steel and alloy materials according to the component content of the plastic die steel, smelting by adopting an electric arc furnace smelting, a ladle refining furnace refining and a vacuum refining furnace refining, and casting by adopting a die casting mode to obtain a die casting electrode blank;
wherein the plastic die steel comprises, by mass, 0.20-0.30% of C, less than or equal to 0.50% of Si, 1.0-2.0% of Mn, 1.0-2.0% of Cr1, less than or equal to 0.60% of Mo, less than or equal to 0.20% of V, 0.5-1.5% of Ni, less than or equal to 0.01% of P, less than or equal to 0.002% of S, and the balance of Fe;
the purity of the steel is improved by combining the improvement of the preparation process and the change of the content of the components. Wherein P is less than or equal to 0.010 percent, S is less than or equal to 0.002 percent, and meanwhile, the accurate control of the component segregation and the inclusion content of the electrode blank is realized through the selection of smelting raw materials, the optimization of a steelmaking process and the control of key control points (such as steel casting temperature and casting speed) of a casting process.
S2, electroslag smelting:
carrying out electroslag remelting on the die-cast electrode blank prepared in the step S1 under the protection of argon by adopting a protective atmosphere electroslag furnace, and then obtaining an electroslag ingot;
the purity of the electroslag ingot is ensured through the protective atmosphere smelting, the proper constant melting speed control, the reasonable pre-melted slag selection and the electrode blank smelting sequence, and the crystal structure, the composition segregation (especially the control of liquated carbide) and the compactness are further improved.
S3, high-temperature homogenization:
carrying out high-temperature diffusion on the electroslag ingot at 1150-1250 ℃, and keeping the temperature for 20-30 h; through long-time high-temperature diffusion, carbides are effectively dissolved and diffused, and the composition segregation of the electroslag ingot is greatly improved.
S4, multidirectional forging:
carrying out upsetting and drawing out on the electroslag ingot subjected to high-temperature homogenization treatment in X, Y, Z three directions, and finally drawing out the electroslag ingot in the Z direction to obtain a finished product, wherein X, Y is two mutually perpendicular diameter directions, Z is the axial direction of the original electroslag ingot, the forging starting temperature is 1150-1200 ℃, and the forging finishing temperature is not less than 900 ℃;
the strip shape and the anisotropy are more effectively improved by multidirectional deformation, full crushing and compaction of as-cast structures and matching with high-temperature diffusion.
S5, heat treatment after forging: the post-forging heat treatment is divided into two steps,
the first step is as follows: air cooling or air cooling the workpiece after multidirectional forging until the surface temperature of the forged piece is 250-350 ℃, then placing the workpiece into an annealing furnace with the furnace temperature of 280-320 ℃, preserving heat for 2-8 h, heating to 640-660 ℃, preserving heat for 5-10h, heating to 900-0 ℃, preserving heat for 930 ℃, preserving heat for 2D h, wherein D is the maximum thickness of the workpiece in the furnace, and the unit is dm, and after heat preservation is finished, hoisting the workpiece to a trolley for air cooling or air cooling to 250-350 ℃; the grain size of the workpiece is further refined and uniform through the cooling and normalizing processes after forging, and the workpiece mixed crystal and tissue unevenness of the forged workpiece caused by the temperature difference of the core surface are improved;
the second step is that: putting the cooled workpiece into an annealing furnace at 280-320 ℃ again, preserving heat for 5-10h, heating to 740-760 ℃, preserving heat for 4-5h, cooling the workpiece to 640-660 ℃ along with the furnace, preserving heat for 5D-7D h, cooling to below 250-300 ℃ along with the furnace, and taking out of the furnace for air cooling;
keeping the temperature of the forging piece isothermal for 4-5h when the temperature of the forging piece surface reaches 750 ℃ in heating, and forming an austenite layer with a certain thickness on the forging piece surface. Because of the high solubility of hydrogen in austenite (about 2 times higher), the hydrogen in the steel will diffuse rapidly from the core to the surface (the hydrogen in the core of the forging is in a supersaturated state and has strong diffusion capacity). Then, the forging is cooled to 640-660 ℃, at the moment, the austenite on the surface layer is converted into pearlite, the solubility of hydrogen is greatly reduced, the diffusion capacity is greatly improved, and the hydrogen is discharged into the atmosphere
S6 pre-hard processing;
the workpiece processed in step S5 is subjected to pre-hard processing.
Preferably, in step S1, the specific steps of electric arc furnace smelting, ladle refining and vacuum refining are as follows:
smelting in an electric furnace A1:
smelting waste steel in an electric furnace, wherein the temperature of molten steel is more than or equal to 1640 ℃, oxidizing and slagging off, adding alloy materials after slagging off and completely melting the alloy materials, then adding lime and fluorite to form alkaline slag, and carrying out dephosphorization and desulfurization treatment on the molten steel melted in the electric furnace; when the temperature of the molten steel is more than or equal to 1630 ℃, adding aluminum wires for deoxidation, and then tapping;
refining in a A2 ladle refining furnace:
after smelting in an electric furnace, the molten steel is transferred into a ladle and lifted to a refining furnace base, and slag materials CaO and CaF are added2Reducing the C-Si powder to produce white slag, and adding corresponding alloy materials according to the deviation of the actual components and the target components of the molten steel in the refining furnace base to finish the operations of component fine adjustment, desulfurization and deoxidation;
refining in a vacuum refining furnace A3:
the vacuum refining furnace is pumped step by step, the final vacuum degree is more than or equal to 67Pa, the vacuum time is maintained for more than 15min for two times, and the target value of the residual gas H is less than or equal to 2.0 ppm; and after degassing is finished, sampling and analyzing, and blowing argon into the crane ladle after the components are qualified.
Preferably, in step S2, the melting rate at the starting point and the melting rate at the end point of the steady-state stage of electroslag smelting are 10-12 kg/min and 8-10 kg/min respectively, so as to obtain an electroslag ingot, and then the furnace cooling is stopped for 100-150 min.
Preferably, in step S3, the specific heating process of the electroslag ingot at 1150-1250 ℃ is as follows: firstly, heating an electroslag ingot to 400-450 ℃, and preserving heat for 5 hours; then heating to 800-850 ℃, and preserving heat for 8 hours; then heating to 1150-1250 ℃ and preserving the heat for 20-30 h.
Preferably, in the first step of step S5, to reduce the thermal stress during the temperature raising process, the temperature is raised to 640-660 ℃ at a rate of 70 ℃/h or less and is kept for 5-10h, and then the temperature is raised to 900-930 ℃ at a rate of 80 ℃/h or less.
Preferably, in the second step of step S5, the thermal stress in the temperature raising process is reduced, the temperature is raised to 740-760 ℃ at a temperature of 70 ℃/h or less, and the temperature is maintained for 4-5 h.
Preferably, in step S6, the specific steps of pre-hardening the workpiece are as follows:
b1 quenching:
sawing the head and the tail of a workpiece after flaw detection, reheating the workpiece to the quenching temperature of 900-930 ℃, preserving heat for 2D h, cooling the workpiece by adopting a water quenching and quenching liquid cooling mode, and finally cooling the workpiece until the temperature of the core part of the workpiece is less than or equal to 250 ℃ and taking out the quenching liquid for air cooling;
b2 tempering:
putting the workpiece into a tempering furnace at 200-300 ℃ for heat preservation for 5-10 hours, then heating to the tempering temperature of 500-550 ℃, preserving the heat for 4D h, then cooling to the temperature below 250 ℃ along with the furnace, discharging the workpiece out of the furnace and air cooling to the room temperature;
b3 secondary tempering:
and (3) putting the secondary workpiece into a tempering furnace at 200-300 ℃ for heat preservation for 5-10 hours, then heating to the tempering temperature of 450-550 ℃ for heat preservation of 4D h, then cooling to below 250 ℃ along with the furnace, discharging and air cooling to room temperature.
And in the step B, cooling the blank in a water quenching liquid cooling double-liquid quenching mode, and simultaneously formulating corresponding cooling processes (different workpieces correspond to different water cooling time and liquid cooling time) for the blanks with different specifications and sizes by using thermal simulation software Deform-HT to ensure that the temperature of the core part of the blank is less than or equal to 250 ℃.
In the steps B2 and B3, the workpiece is kept at 250 ℃, so that the residual austenite in the quenched workpiece can be subjected to phase transformation again, the quenching stress is reduced, and cracking is avoided.
Preferably, in the steps B2 and B3 of the step S6, in order to reduce the thermal stress in the cooling process, the excessive cooling speed can cause the excessive internal stress of the workpiece, and the workpiece is cooled to below 250 ℃ along with the furnace at the speed of less than or equal to 30 ℃/h and then is discharged from the furnace and cooled to the room temperature.
Another object of the present invention is to provide a pre-hardened high-polished plastic mold steel prepared according to the above preparation method.
Compared with the prior art, the production process of the pre-hardened high-polishing plastic mold steel has the following advantages:
(1) based on common plastic die steel, the prepared product has excellent purity, texture uniformity and mechanical property by adopting special smelting, forging and heat treatment processes. The die made of the material can better meet the requirements of modern industrial production on high-end dies;
(2) by adding the electroslag remelting process, the purity of the steel is greatly improved, and external gas can be prevented from entering molten steel in the atmosphere protection electroslag remelting process, so that the gas content in the molten steel cannot be increased;
(3) by means of ultrahigh-temperature long-time high-temperature homogenization treatment, carbides are effectively dissolved and diffused, and segregation of the electroslag ingot is greatly improved;
(4) by multidirectional forging and full compaction of the fully-forged cast structure, the banded segregation and anisotropy of the workpiece can be effectively improved;
(5) by implementing a reasonable heat treatment process after forging, the grain size of a workpiece is more refined, the possibility of white point defects of the nickel-containing steel can be inhibited, the principle that the solubility of hydrogen in different tissue states is different is fully utilized by the hydrogen diffusion process, the hydrogen in the steel can be diffused and escaped by a simpler mode, the period is short, the rhythm is fast, and the practical value is high;
(6) the workpiece is enabled to obtain a better quenching effect in the quenching process by a water + quenching liquid double-liquid quenching mode, the workpiece can quickly pass through the nose tip of a steel continuous Cooling Curve (CCT) in a high-temperature section by a water cooling mode to obtain a better quenching cooling transformation structure, and the workpiece is placed into the quenching liquid for cooling in a low-temperature section, so that the workpiece can not crack in the cooling process at the temperature below a martensite transformation point (MS);
(7) the invention provides high-grade plastic die steel with high polishing and high uniformity, and the product can be rated by more than 90 under the polishing condition of 12000 #. The product can be widely used for automobile interior trim part molds, such as instrument panel molds, sound box molds, household appliances (television set cover, air conditioner shell molds) and the like.
Drawings
FIG. 1 is a microstructure of die steel obtained in example 1;
FIG. 2 is a microstructure of the die steel obtained in example 2;
FIG. 3 is a microstructure of die steel obtained in example 3;
FIG. 4 shows the microstructure of the die steel obtained in example 4.
Detailed Description
The invention is further described below with reference to the following figures and specific examples.
Example 1
A pre-hardened high-finish plastic die steel consisting essentially of, in mass fractions, the elements as in table 1:
TABLE 1
A production process of pre-hardened high-polishing plastic mold steel mainly comprises the following steps:
s1, smelting an electrode blank:
batching scrap steel and alloy materials according to the component content of the plastic mold steel, smelting by adopting an electric arc furnace smelting, a ladle refining furnace refining and a vacuum refining furnace refining, and then casting by adopting a die casting mode to obtain a die casting electrode blank; the method comprises the following steps of electric arc furnace smelting, ladle refining furnace refining and vacuum refining furnace refining:
smelting in an electric furnace A1:
smelting waste steel in an electric furnace, wherein the temperature of molten steel is more than or equal to 1640 ℃, oxidizing and slagging off, adding alloy materials after slagging off and completely melting the alloy materials, then adding lime and fluorite to form alkaline slag, and carrying out dephosphorization and desulfurization treatment on the molten steel melted in the electric furnace; when the temperature of the molten steel is more than or equal to 1630 ℃, adding aluminum wires for deoxidation, and then tapping;
refining in a A2 ladle refining furnace:
after smelting in an electric furnace, the molten steel is transferred into a ladle and lifted to a refining furnace base, and slag materials CaO and CaF are added2Reducing the C-Si powder to produce white slag, and adding corresponding alloy materials according to the deviation of the actual components and the target components of the molten steel in the refining furnace base to finish the operations of component fine adjustment, desulfurization and deoxidation;
refining in a vacuum refining furnace A3:
the vacuum refining furnace is pumped step by step, the final vacuum degree is 67Pa, the vacuum time is maintained for 15min for two times, and the target value of the residual gas H is less than or equal to 2.0 ppm; and after degassing is finished, sampling and analyzing, and blowing argon into the crane ladle after the components are qualified.
S2, electroslag smelting:
carrying out electroslag remelting on the die-cast electrode blank prepared in the step S1 under the protection of argon by adopting a protective atmosphere electroslag furnace, and then obtaining an electroslag ingot; wherein, the melting speed value at the starting point of the stable-state stage of electroslag smelting is 10kg/min, the melting speed value at the end point is 8kg/min, an electroslag ingot is obtained, and then furnace cooling is stopped for 110 min.
S3, high-temperature homogenization:
carrying out high-temperature diffusion on the electroslag ingot at 1230 ℃, and keeping the temperature for 30 h; the specific heating process of the electroslag ingot at 1230 ℃ is as follows: firstly, heating an electroslag ingot to 450 ℃, and preserving heat for 5 hours; then heating to 850 ℃, and preserving heat for 8 hours; then heating to 1230 ℃, and keeping the temperature for 30 h.
S4, multidirectional forging:
carrying out upsetting and drawing out on the electroslag ingot subjected to high-temperature homogenization treatment in X, Y, Z three directions, and finally drawing out the electroslag ingot in the Z direction to obtain a finished product, wherein X, Y is two mutually perpendicular diameter directions, Z is the axial direction of the original electroslag ingot, the forging starting temperature is 1160 ℃, and the forging finishing temperature is 910 ℃;
s5, heat treatment after forging: the post-forging heat treatment is divided into two steps,
the first step is as follows: air cooling or air cooling the workpiece after multidirectional forging until the surface temperature of the forged piece is 280 ℃, then loading the workpiece into an annealing furnace with the furnace temperature of 300 ℃, preserving heat for 5 hours, heating to 650 ℃ at the speed of 60 ℃/h, preserving heat for 5 hours, heating to 910 ℃ at the speed of 60 ℃/h, preserving heat for 2D h, D is the maximum thickness of the workpiece in the furnace, and the unit is dm, and hanging down a trolley for air cooling or air cooling to 300 ℃ after heat preservation;
the second step is that: putting the cooled workpiece into an annealing furnace at 300 ℃ again, preserving heat for 5h, heating to 750 ℃ at a speed of 60 ℃/h, preserving heat for 5h, cooling the workpiece to 650 ℃ along with the furnace, preserving heat for 5D h, cooling to below 250 ℃ along with the furnace, discharging and air cooling;
s6 pre-hard processing;
pre-hardening the workpiece processed in the step S5; the specific steps of pre-hardening the workpiece are as follows:
b1 quenching:
sawing the head and the tail of a workpiece after flaw detection, reheating the workpiece to the quenching temperature of 900 ℃, preserving heat by 2D h, cooling the workpiece by adopting a water quenching and quenching liquid cooling mode, and finally cooling the workpiece until the temperature of the core part of the workpiece is less than or equal to 250 ℃ and taking out the quenching liquid for air cooling;
b2 tempering:
putting the workpiece into a tempering furnace at 250 ℃ for heat preservation for 10 hours, then heating to the tempering temperature of 530 ℃, preserving the heat for 4D h, then cooling to the temperature below 250 ℃ along with the furnace, discharging the workpiece out of the furnace, and air cooling to the room temperature;
b3 secondary tempering:
and (3) putting the secondary workpiece into a tempering furnace at 250 ℃ for heat preservation for 10 hours, then heating to the tempering temperature of 540 ℃ for heat preservation of 4D h, then cooling to the temperature below 250 ℃ along with the furnace, discharging the workpiece out of the furnace, and air cooling to the room temperature.
Wherein, in the steps B2 and B3, the workpiece is cooled to below 250 ℃ along with the furnace at the speed of less than or equal to 30 ℃/h, taken out of the furnace and cooled to room temperature.
Example 2
A pre-hardened high-finish plastic die steel consisting essentially of, in mass fractions, the elements as in table 2:
TABLE 2
A production process of pre-hardened high-polishing plastic mold steel mainly comprises the following steps:
s1, smelting an electrode blank:
batching scrap steel and alloy materials according to the component content of the plastic mold steel, smelting by adopting an electric arc furnace smelting, a ladle refining furnace refining and a vacuum refining furnace refining, and then casting by adopting a die casting mode to obtain a die casting electrode blank; the method comprises the following steps of electric arc furnace smelting, ladle refining furnace refining and vacuum refining furnace refining:
smelting in an electric furnace A1:
smelting waste steel in an electric furnace, wherein the temperature of molten steel is more than or equal to 1640 ℃, oxidizing and slagging off, adding alloy materials after slagging off and completely melting the alloy materials, then adding lime and fluorite to form alkaline slag, and carrying out dephosphorization and desulfurization treatment on the molten steel melted in the electric furnace; when the temperature of the molten steel is more than or equal to 1630 ℃, adding aluminum wires for deoxidation, and then tapping;
refining in a A2 ladle refining furnace:
after smelting in an electric furnace, the molten steel is transferred into a ladle and lifted to a refining furnace base, and slag materials CaO and CaF are added2Reducing the C-Si powder to produce white slag, and adding corresponding alloy materials according to the deviation of the actual components and the target components of the molten steel in the refining furnace base to finish the operations of component fine adjustment, desulfurization and deoxidation;
a3 refining in a vacuum refining furnace:
the vacuum refining furnace is pumped step by step, the final vacuum degree is 68Pa, the vacuum time is maintained for 15min twice, and the target value of the residual gas H is less than or equal to 2.0 ppm; and after degassing is finished, sampling and analyzing, and blowing argon into the crane ladle after the components are qualified.
S2, electroslag smelting:
carrying out electroslag remelting on the die-cast electrode blank prepared in the step S1 under the protection of argon by adopting a protective atmosphere electroslag furnace, and then obtaining an electroslag ingot; wherein the melting speed value at the starting point of the stable-state electroslag smelting stage is 11kg/min, the melting speed value at the end point is 9kg/min, an electroslag ingot is obtained, and then furnace cooling is stopped for 120 min.
S3, high-temperature homogenization:
carrying out high-temperature diffusion on the electroslag ingot at 1240 ℃ and keeping the temperature for 28 h; wherein the specific heating process of the electroslag ingot at 1240 ℃ is as follows: firstly, heating an electroslag ingot to 450 ℃, and preserving heat for 5 hours; then heating to 850 ℃, and preserving heat for 8 hours; then heating to 1240 ℃ and keeping the temperature for 28 h.
S4, multidirectional forging:
carrying out upsetting and drawing out on the electroslag ingot subjected to high-temperature homogenization treatment in X, Y, Z three directions, and finally drawing out the electroslag ingot in the Z direction to obtain a finished product, wherein X, Y is two mutually perpendicular diameter directions, Z is the axial direction of the original electroslag ingot, the forging starting temperature is 1170 ℃, and the forging finishing temperature is 920 ℃;
s5, heat treatment after forging: the post-forging heat treatment is divided into two steps,
the first step is as follows: air cooling or air cooling the workpiece after multidirectional forging until the surface temperature of the forged piece is 320 ℃, then loading the workpiece into an annealing furnace with the furnace temperature of 320 ℃, preserving heat for 5 hours, heating to 650 ℃ at the speed of 60 ℃/h, preserving heat for 5 hours, heating to 915 ℃ at the speed of 70 ℃/h, preserving heat for 2D h, wherein D is the maximum thickness of the workpiece in the furnace, and the unit is dm, and hanging down a trolley for air cooling or air cooling to 300 ℃ after heat preservation;
the second step is that: putting the cooled workpiece into an annealing furnace at 300 ℃ again, preserving heat for 5h, heating to 750 ℃ at a speed of 60 ℃/h, preserving heat for 5h, cooling the workpiece to 650 ℃ along with the furnace, preserving heat for 6D h, cooling to below 250 ℃ along with the furnace, discharging and air cooling;
s6 pre-hard processing;
pre-hardening the workpiece processed in the step S5; the specific steps of pre-hardening the workpiece are as follows:
b1 quenching:
sawing the head and the tail of a workpiece after flaw detection, reheating the workpiece to the quenching temperature of 915 ℃, preserving heat by 2D h, cooling the workpiece by adopting a water quenching and quenching liquid cooling mode, and finally cooling the workpiece until the temperature of the core part of the workpiece is less than or equal to 250 ℃ and taking out the quenching liquid for air cooling;
b2 tempering:
putting the workpiece into a tempering furnace at 250 ℃ for heat preservation for 8 hours, then heating to the tempering temperature of 530 ℃, preserving the heat for 4D h, then cooling to the temperature below 250 ℃ along with the furnace, discharging the workpiece out of the furnace, and air cooling to the room temperature;
b3 secondary tempering:
and (3) putting the secondary workpiece into a tempering furnace at 250 ℃ for heat preservation for 8 hours, then heating to the tempering temperature of 520 ℃ for heat preservation of 4D h, then cooling to below 250 ℃ along with the furnace, discharging from the furnace, and air cooling to room temperature.
Wherein, in the steps B2 and B3, the workpiece is cooled to below 250 ℃ along with the furnace at the speed of less than or equal to 30 ℃/h, taken out of the furnace and cooled to room temperature.
Example 3
A pre-hardened high-finish plastic die steel consisting essentially of, in mass fractions, the elements as in table 3:
TABLE 3
A production process of pre-hardened high-polishing plastic mold steel mainly comprises the following steps:
s1, smelting an electrode blank:
batching scrap steel and alloy materials according to the component content of the plastic mold steel, smelting by adopting an electric arc furnace smelting, a ladle refining furnace refining and a vacuum refining furnace refining, and then casting by adopting a die casting mode to obtain a die casting electrode blank; the method comprises the following steps of electric arc furnace smelting, ladle refining furnace refining and vacuum refining furnace refining:
smelting in an electric furnace A1:
smelting waste steel in an electric furnace, wherein the temperature of molten steel is more than or equal to 1640 ℃, oxidizing and slagging off, adding alloy materials after slagging off and completely melting the alloy materials, then adding lime and fluorite to form alkaline slag, and carrying out dephosphorization and desulfurization treatment on the molten steel melted in the electric furnace; when the temperature of the molten steel is more than or equal to 1630 ℃, adding aluminum wires for deoxidation, and then tapping;
refining in a A2 ladle refining furnace:
after smelting in an electric furnace, the molten steel is transferred into a ladle and lifted to a refining furnace base, and slag materials CaO and CaF are added2Reducing the C-Si powder to produce white slag, and adding corresponding alloy material according to the deviation of the actual composition and the target composition of the molten steel in the refining furnace baseFinishing the operations of component fine adjustment, desulfurization and deoxidation;
refining in a vacuum refining furnace A3:
the vacuum refining furnace is pumped step by step, the final vacuum degree is 67Pa, the vacuum time is maintained for more than 18min for two times, and the target value of the residual gas H is less than or equal to 2.0 ppm; and after degassing is finished, sampling and analyzing, and blowing argon into the crane ladle after the components are qualified.
S2, electroslag smelting:
carrying out electroslag remelting on the die-cast electrode blank prepared in the step S1 under the protection of argon by adopting a protective atmosphere electroslag furnace, and then obtaining an electroslag ingot; wherein the melting speed value at the starting point of the stable-state electroslag smelting stage is 10.5kg/min, the melting speed value at the end point is 9kg/min, an electroslag ingot is obtained, and then furnace cooling is stopped for 120 min.
S3, high-temperature homogenization:
carrying out high-temperature diffusion on the electroslag ingot at 1250 ℃, and keeping the temperature for 25 h; wherein the specific heating process of the electroslag ingot at 1250 ℃ is as follows: firstly, heating an electroslag ingot to 450 ℃, and preserving heat for 5 hours; then heating to 850 ℃, and preserving heat for 8 hours; then heating to 1250 ℃ and keeping the temperature for 25 h.
S4, multidirectional forging:
carrying out upsetting and drawing out on the electroslag ingot subjected to high-temperature homogenization treatment in X, Y, Z three directions, and finally drawing out the electroslag ingot in the Z direction to obtain a finished product, wherein X, Y is two mutually perpendicular diameter directions, Z is the axial direction of the original electroslag ingot, the forging starting temperature is 1200 ℃, and the forging finishing temperature is more than or equal to 930 ℃;
s5, heat treatment after forging: the post-forging heat treatment is divided into two steps,
the first step is as follows: air cooling or air cooling the workpiece after multidirectional forging until the surface temperature of the forged piece is 300 ℃, then placing the workpiece into an annealing furnace with the furnace temperature of 300 ℃, preserving heat for 6 hours, heating to 650 ℃ at 40 ℃/h, preserving heat for 10 hours, heating to 930 ℃ at 60 ℃/h, preserving heat for 2D h, wherein D is the maximum thickness of the workpiece in the furnace, and the unit is dm, and hanging down a trolley for air cooling or air cooling to 300 ℃ after heat preservation;
the second step is that: putting the cooled workpiece into an annealing furnace at 300 ℃ again, preserving heat for 6h, heating to 750 ℃ at a speed of 40 ℃/h, preserving heat for 5h, cooling the workpiece to 650 ℃ along with the furnace, preserving heat for 7D h, cooling to below 260 ℃ along with the furnace, discharging and air cooling;
s6 pre-hard processing;
pre-hardening the workpiece processed in the step S5; the specific steps of pre-hardening the workpiece are as follows:
b1 quenching:
sawing the head and the tail of a workpiece after flaw detection, reheating the workpiece to the quenching temperature of 930 ℃, preserving heat by 2D h, cooling the workpiece by adopting a water quenching and quenching liquid cooling mode, and finally cooling the workpiece until the temperature of the core part of the workpiece is less than or equal to 250 ℃ and taking out the quenching liquid for air cooling;
b2 tempering:
putting the workpiece into a tempering furnace at 250 ℃ for heat preservation for 6 hours, then heating to the tempering temperature of 525 ℃, preserving the heat for 4D h, then cooling to the temperature below 250 ℃ along with the furnace, discharging the workpiece out of the furnace, and air cooling to the room temperature;
b3 secondary tempering:
and (3) putting the secondary workpiece into a tempering furnace at 250 ℃ for heat preservation for 6 hours, then heating to the tempering temperature of 510 ℃ for heat preservation of 4D h, then cooling to the temperature below 250 ℃ along with the furnace, discharging the workpiece out of the furnace, and air cooling to the room temperature.
Wherein, in the steps B2 and B3, the workpiece is cooled to below 250 ℃ along with the furnace at the speed of less than or equal to 30 ℃/h, taken out of the furnace and cooled to room temperature.
Example 4
A pre-hardened high-finish plastic die steel consisting essentially of, in mass fractions, the elements as in table 3:
TABLE 3
A production process of pre-hardened high-polishing plastic mold steel mainly comprises the following steps:
s1, smelting an electrode blank:
batching scrap steel and alloy materials according to the component content of the plastic mold steel, smelting by adopting an electric arc furnace smelting, a ladle refining furnace refining and a vacuum refining furnace refining, and then casting by adopting a die casting mode to obtain a die casting electrode blank; the method comprises the following steps of electric arc furnace smelting, ladle refining furnace refining and vacuum refining furnace refining:
smelting in an electric furnace A1:
smelting waste steel in an electric furnace, wherein the temperature of molten steel is more than or equal to 1640 ℃, oxidizing and slagging off, adding alloy materials after slagging off and completely melting the alloy materials, then adding lime and fluorite to form alkaline slag, and carrying out dephosphorization and desulfurization treatment on the molten steel melted in the electric furnace; when the temperature of the molten steel is more than or equal to 1630 ℃, adding aluminum wires for deoxidation, and then tapping;
refining in a A2 ladle refining furnace:
after smelting in an electric furnace, the molten steel is transferred into a ladle and lifted to a refining furnace base, and slag materials CaO and CaF are added2Reducing C-Si powder to produce white slag, and adding corresponding alloy materials according to the deviation of actual components and target components of molten steel in the refining furnace base to finish component fine adjustment, desulfurization and deoxidation operations;
refining in a vacuum refining furnace A3:
the vacuum refining furnace is pumped step by step, the final vacuum degree is 68Pa, the vacuum time is maintained for more than 19min for two times, and the target value of the residual gas H is less than or equal to 2.0 ppm; and after degassing is finished, sampling and analyzing, and blowing argon into the crane ladle after the components are qualified.
S2, electroslag smelting:
carrying out electroslag remelting on the die-cast electrode blank prepared in the step S1 under the protection of argon by adopting a protective atmosphere electroslag furnace, and then obtaining an electroslag ingot; wherein the melting speed value at the starting point of the steady-state stage of electroslag smelting is 12kg/min, the melting speed value at the end point is 8kg/min, an electroslag ingot is obtained, and then furnace cooling is stopped for 150 min.
S3, high-temperature homogenization:
carrying out high-temperature diffusion on the electroslag ingot at 1250 ℃, and keeping the temperature for 30 h; wherein the specific heating process of the electroslag ingot at 1250 ℃ is as follows: firstly, heating an electroslag ingot to 400 ℃, and preserving heat for 5 hours; then heating to 800 ℃, and preserving heat for 8 hours; then heating to 1250 ℃ and keeping the temperature for 30 h.
S4, multidirectional forging:
carrying out upsetting and drawing out on the electroslag ingot subjected to high-temperature homogenization treatment in X, Y, Z three directions, and finally drawing out the electroslag ingot in the Z direction to obtain a finished product, wherein X, Y is two mutually perpendicular diameter directions, Z is the axial direction of the original electroslag ingot, the forging starting temperature is 1190 ℃, and the forging finishing temperature is more than or equal to 930 ℃;
s5, heat treatment after forging: the post-forging heat treatment is divided into two steps,
the first step is as follows: air cooling or air cooling the workpiece after multidirectional forging until the surface temperature of the forged piece is 250 ℃, then loading the workpiece into an annealing furnace with the furnace temperature of 280 ℃, preserving heat for 5 hours, heating to 650 ℃ at the speed of 50 ℃/h, preserving heat for 5 hours, heating to 930 ℃ at the speed of 60 ℃/h, preserving heat for 2D h, D is the maximum thickness of the workpiece in the furnace, and the unit is dm, and hanging down a trolley for air cooling or air cooling to 250 ℃ after heat preservation;
the second step is that: putting the cooled workpiece into a 280 ℃ annealing furnace again, preserving heat for 5h, heating to 750 ℃ at a speed of 50 ℃/h, preserving heat for 5h, cooling the workpiece to 650 ℃ along with the furnace, preserving heat for 7D h, cooling to below 250 ℃ along with the furnace, discharging and air cooling;
s6 pre-hard processing;
pre-hardening the workpiece processed in the step S5; the specific steps of pre-hardening the workpiece are as follows:
b1 quenching:
sawing the head and the tail of a workpiece after flaw detection, reheating the workpiece to the quenching temperature of 920 ℃, preserving heat by 2D h, cooling the workpiece by adopting a water quenching and quenching liquid cooling mode, and finally cooling the workpiece until the temperature of the core part of the workpiece is less than or equal to 250 ℃ and taking out the quenching liquid for air cooling;
b2 tempering:
putting the workpiece into a tempering furnace at 250 ℃ for heat preservation for 5 hours, then heating to the tempering temperature of 500 ℃, preserving the heat for 4D h, then cooling to the temperature below 250 ℃ along with the furnace, discharging the workpiece out of the furnace, and air cooling to the room temperature;
b3 secondary tempering:
and (3) putting the secondary workpiece into a tempering furnace at 250 ℃ for heat preservation for 10 hours, then heating to the tempering temperature of 510 ℃ and preserving the heat at 4D h, then cooling to the temperature below 250 ℃ along with the furnace, discharging the workpiece out of the furnace and air cooling to the room temperature.
Wherein, in the steps B2 and B3, the workpiece is cooled to below 250 ℃ along with the furnace at the speed of less than or equal to 30 ℃/h, taken out of the furnace and cooled to room temperature.
In order to verify the mechanical properties of the hot-work die steel provided by the preparation method of the present invention, the inventors respectively obtained 4 samples from the die steels obtained in examples 1 to 4, and performed electron microscope scanning and property detection, wherein the detection data are shown in table 5:
TABLE 5
Thus, 1, as shown in fig. 1 to 4, the pre-hardened microstructure of the die material is uniform, is fine acicular sorbite and a small amount of free ferrite, is graded according to the GB/T11354-2005 standard, is in grade 2-3, and has the grain size of more than 8;
2, the die material is polished and detected, and the polishing scores of the die material are over 90 points under the 12000# polishing grade, and the die material belongs to excellent grade;
3, from the hardness detection data of the embodiments 1 to 4, it can be found that the die steel produced by the same process parameter under the same composition has very uniform hardness, and the hardness fluctuation range is about +/-0.5 HRC.
Therefore, the die steel prepared by the preparation method has excellent polishing performance and excellent structure uniformity.
Claims (9)
1. A production process of pre-hardened high-polishing plastic mold steel is characterized by mainly comprising the following steps:
s1, smelting an electrode blank:
batching scrap steel and alloy materials according to the component content of the plastic mold steel, smelting by adopting an electric arc furnace smelting, a ladle refining furnace refining and a vacuum refining furnace refining, and then casting by adopting a die casting mode to obtain a die casting electrode blank;
wherein the plastic die steel comprises, by mass, 0.20-0.30% of C, less than or equal to 0.50% of Si, 1.0-2.0% of Mn, 1.0-2.0% of Cr, less than or equal to 0.60% of Mo, less than or equal to 0.20% of V, 0.5-1.5% of Ni, less than or equal to 0.01% of P, less than or equal to 0.002% of S, and the balance of Fe;
s2, electroslag smelting:
carrying out electroslag remelting on the die-cast electrode blank prepared in the step S1 under the protection of argon by adopting a protective atmosphere electroslag furnace, and then obtaining an electroslag ingot;
s3, high-temperature homogenization:
carrying out high-temperature diffusion on the electroslag ingot at 1150-1250 ℃, and keeping the temperature for 20-30 h;
s4, multidirectional forging:
carrying out upsetting and drawing out on the electroslag ingot subjected to high-temperature homogenization treatment in X, Y, Z three directions, and finally drawing out the electroslag ingot in the Z direction to obtain a finished product, wherein X, Y is two mutually perpendicular diameter directions, Z is the axial direction of the original electroslag ingot, the forging starting temperature is 1150-1200 ℃, and the forging finishing temperature is not less than 900 ℃;
s5, heat treatment after forging: the post-forging heat treatment is divided into two steps,
the first step is as follows: air cooling or air cooling the workpiece after multidirectional forging until the surface temperature of the forged piece is 250-350 ℃, then placing the workpiece into an annealing furnace with the furnace temperature of 280-320 ℃, preserving heat for 2-8 h, heating to 640-660 ℃, preserving heat for 5-10h, heating to 900-0 ℃, preserving heat for 930 ℃, preserving heat for 2D h, wherein D is the maximum thickness of the workpiece in the furnace, and the unit is dm, and after heat preservation is finished, hoisting the workpiece to a trolley for air cooling or air cooling to 250-350 ℃;
the second step is that: putting the cooled workpiece into an annealing furnace at 280-320 ℃ again, preserving heat for 5-10h, heating to 740-760 ℃, preserving heat for 4-5h, cooling the workpiece to 640-660 ℃ along with the furnace, preserving heat for 5D-7D h, cooling to below 250-300 ℃ along with the furnace, and taking out of the furnace for air cooling;
s6 pre-hard processing;
the workpiece processed in step S5 is subjected to pre-hard processing.
2. The manufacturing process of pre-hardened high-polishing plastic mold steel according to claim 1, wherein in step S1, the specific steps of electric arc furnace smelting, ladle refining furnace refining and vacuum refining furnace refining are as follows:
smelting in an electric furnace A1:
smelting waste steel in an electric furnace, wherein the temperature of molten steel is more than or equal to 1640 ℃, oxidizing and slagging off, adding alloy materials after slagging off and completely melting the alloy materials, then adding lime and fluorite to form alkaline slag, and carrying out dephosphorization and desulfurization treatment on the molten steel melted in the electric furnace; when the temperature of the molten steel is more than or equal to 1630 ℃, adding aluminum wires for deoxidation, and then tapping;
refining in a A2 ladle refining furnace:
after smelting in an electric furnace, the molten steel is transferred into a ladle and lifted to a refining furnace base, and slag materials CaO and CaF are added2Reducing the C-Si powder to produce white slag, and adding corresponding alloy materials according to the deviation of the actual components and the target components of the molten steel in the refining furnace base to finish the operations of component fine adjustment, desulfurization and deoxidation;
refining in a vacuum refining furnace A3:
the vacuum refining furnace is pumped step by step, the final vacuum degree is more than or equal to 67Pa, the vacuum time is maintained for more than 15min for two times, and the target value of the residual gas H is less than or equal to 2.0 ppm; and after degassing is finished, sampling and analyzing, and blowing argon into the crane ladle after the components are qualified.
3. The process for producing a pre-hardened high-polishing plastic mold steel as claimed in claim 1, wherein in step S2, the melting rate at the start point and the melting rate at the end point of the steady-state electroslag smelting stage are 10-12 kg/min and 8-10 kg/min respectively, so as to obtain an electroslag ingot, and then the furnace cooling is stopped for 100-150 min.
4. The process for producing a pre-hardened high-polishing plastic mold steel as claimed in claim 1, wherein in step S3, the specific heating process of the electroslag ingot at 1150-1250 ℃ is as follows: firstly, heating an electroslag ingot to 400-450 ℃, and preserving heat for 5 hours; then heating to 800-850 ℃, and preserving heat for 8 hours; then heating to 1150-1250 ℃ and preserving the heat for 20-30 h.
5. The process for producing pre-hardened high-polishing plastic mold steel as claimed in claim 1, wherein in the first step of step S5, the temperature is raised to 640-660 ℃ at a rate of 70 ℃/h or less and kept for 5-10h, and then raised to 900-930 ℃ at a rate of 80 ℃/h or less.
6. The manufacturing process of pre-hardened high-polishing plastic mold steel as claimed in claim 5, wherein in the second step of step S5, the temperature is raised to 740-760 ℃ at a rate of 70 ℃/h or less, and the temperature is maintained for 4-5 h.
7. The manufacturing process of pre-hardened high-polishing plastic mold steel as claimed in claim 1, wherein in step S6, the pre-hardening treatment of the workpiece comprises the following steps:
b1 quenching:
sawing the head and the tail of a workpiece after flaw detection, reheating the workpiece to the quenching temperature of 900-930 ℃, preserving heat for 2D h, cooling the workpiece by adopting a water quenching and quenching liquid cooling mode, and finally cooling the workpiece until the temperature of the core part of the workpiece is less than or equal to 250 ℃ and taking out the quenching liquid for air cooling;
b2 tempering:
putting the workpiece into a tempering furnace at 200-300 ℃ for heat preservation for 5-10 hours, then heating to the tempering temperature of 500-550 ℃, preserving the heat for 4D h, then cooling to the temperature below 250 ℃ along with the furnace, discharging the workpiece out of the furnace and air cooling to the room temperature;
b3 secondary tempering:
and (3) putting the secondary workpiece into a tempering furnace at 200-300 ℃ for heat preservation for 5-10 hours, then heating to the tempering temperature of 450-550 ℃ and preserving the heat for 4D h, then cooling to below 250 ℃ along with the furnace, discharging the furnace, and air cooling to room temperature.
8. The process for producing a pre-hardened high-finish plastic mold steel as claimed in claim 7, wherein in steps B2 and B3 of step S6, the workpiece is furnace cooled to below 250 ℃ at a rate of less than or equal to 30 ℃/h, and then taken out of the furnace and air-cooled to room temperature.
9. A pre-hardened high-polishing plastic mold steel prepared according to the preparation method of any one of claims 1 to 8.
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| CN116904865A (en) * | 2023-09-14 | 2023-10-20 | 成都先进金属材料产业技术研究院股份有限公司 | Large-specification 3Cr17 plastic die steel and production method thereof |
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Denomination of invention: Production process of pre hardened high polished plastic mold steel Granted publication date: 20221213 Pledgee: Bank of Jiangsu Limited by Share Ltd. Wuxi branch Pledgor: Jiangsu Hongsheng mould steel material technology Co.,Ltd. Registration number: Y2024980026024 |
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