CN111826589A - Plastic die steel with high strength and high corrosion resistance and preparation method thereof - Google Patents

Plastic die steel with high strength and high corrosion resistance and preparation method thereof Download PDF

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CN111826589A
CN111826589A CN202010644708.6A CN202010644708A CN111826589A CN 111826589 A CN111826589 A CN 111826589A CN 202010644708 A CN202010644708 A CN 202010644708A CN 111826589 A CN111826589 A CN 111826589A
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die steel
steel
temperature
corrosion resistance
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CN111826589B (en
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冯丹竹
赵坦
隋广雨
隋轶
范刘群
张宏亮
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Angang Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C21D1/32—Soft annealing, e.g. spheroidising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • 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
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
    • 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
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron

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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 Articles (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

The invention provides a plastic die steel with high strength and high corrosion resistance and a preparation method thereof, wherein the die steel comprises the following components in percentage by weight: c: 0.20% -0.30%, Si: 0.52% -0.65%, Mn: 0.65-0.80%, P is less than or equal to 0.015%, S is less than or equal to 0.015%, Cr: 11.0% -12.0%, Mo: 0.20% -0.40%, Sn: 0.06% -0.09%, Nb: 0.10% -0.20%, B: 0.001-0.002%, and the balance of Fe and inevitable impurities. The preparation method comprises the steps of molten iron pretreatment, smelting, LF-RH, continuous casting, slab heating, rolling, straightening, slow cooling and heat treatment; the die steel produced by the invention has the hardness of 37-40HRC, the same plate hardness difference of less than or equal to 2HRC, the central transverse tensile strength of more than or equal to 1020MPa, the yield strength of more than or equal to 860MPa, the elongation of more than or equal to 20 percent, the central transverse impact performance of more than or equal to 18J, and excellent corrosion resistance.

Description

Plastic die steel with high strength and high corrosion resistance and preparation method thereof
Technical Field
The invention belongs to the field of metal materials, and particularly relates to plastic die steel with high strength and high corrosion resistance and a preparation method thereof.
Background
In the production of plastic articles starting from chemically aggressive plastics, the moulds must have corrosion-inhibiting properties. The corrosion prevention method can be chrome plating or nickel plating, but the groove of the die is difficult to obtain a uniform plating layer, and the die is easy to crack and peel off the plating layer; in addition, because the sharp angle can not be kept to be completely closed after the plating of the die, thicker burrs are often formed on the formed plastic part, so the plating on the plastic die is gradually eliminated, and a corrosion-resistant steel die is adopted instead. For corrosion-resistant steels for such applications, certain hardness, strength, toughness, and the like are also required. At present, domestic die steel users generally use S136 series steel grades, but the cost is higher, the toughness and the plasticity are poorer, and the die market with the increasingly-improved requirements is more and more difficult to meet.
A large amount of work is done by many domestic units in the aspects of developing and developing novel high-strength high-corrosion-resistance plastic die steel, improving the metallurgical and rolling quality, optimizing the heat treatment process, prolonging the service life of the die and the like.
The invention relates to high-strength die steel with application number 201711443143.X, and discloses high-strength die steel, which comprises the following components in percentage by mass: c: 0.30% -0.42%, Cr: 2.5% -3.5%, Mn: 0.25% -0.45%, Ni: 1.3% -1.5%, Si: 0.3% -0.45%, V: 0.4-0.6%, Mo is 2.5-3.0%, W: 0.1% -0.25%, Sn: 0.01 to 0.02 percent of the total weight of the alloy, and the balance of iron and a small amount of impurities. The high-strength die steel has strong high-temperature resistance, stable performance, good wear resistance and corrosion resistance, and prolonged service life, but has no specific production method and performance indexes, and the performance indexes are difficult to quantify.
The invention with application number 201410194383.0, namely the ultrahigh-strength die steel with good corrosion resistance and toughness, comprises the following components in percentage by mass: 0.08% -0.32%, Si: less than or equal to 0.8 percent, Mn: less than or equal to 0.5 percent, Cr: 5% -10%, Ni: 6.0% -8.0%, Co: 1.3% -1.8%, W: 0.9% -1.1%, V: 0.2% -0.5%, Nb: 0.08% -0.15%, N: less than or equal to 0.002%, O: less than or equal to 0.0015 percent, Mo: 0.9% -1.4%, Ti: 0.05% -0.4%, S: 0.011 percent to 0.025 percent. The die steel can be widely applied to the automobile industry requiring high strength and high toughness through forging processing means. But the forging cost is high, the yield is low, and the impact performance of the plastic die steel is difficult to ensure.
The invention discloses a heat treatment method of high-nitrogen high-corrosion-resistance plastic die steel with application number 201811285368.1, which comprises the following components in percentage by weight: 0.35% -0.45%, Si: 0.3% -0.5%, Mn: 0.3% -0.6%, Cr: 13.0% -14.0%, Mo: 0.05% -0.08%, N: 0.06% -0.08%. The invention adopts the steps of spheroidizing annealing, salt bath quenching and tempering distribution, and element distribution is completed in the tempering stage to obtain the plastic die steel with excellent performance. But the section size of the die steel is small, the die steel is greatly limited by a heating furnace, and the die steel is difficult to realize in large-scale production.
Invention "a plastic die steel with corrosion resistance and manufacturing method thereof" of application No. 201711181166.8 wherein: 0.45% -0.55%, Si: 0.40% -0.80%, Mn: 0.80% -1.60%, V: 0.10% -0.25%, N: 0.007% -0.015%, Al: 0.005% -0.050%, Ni: 3.5% -4.0%, Cr: 8.5% -10.5%, Cu: 0.25 to 0.45 percent of Cr and Ni, 12 to 14.5 percent of Cr and Ni, and the production process route of forging, heat preservation tempering, rough machining, hot rolling, high temperature tempering, finish machining, forging, tempering and cooling is complex, the production period is long, and the method is not in line with the development direction of the current die manufacturing industry.
Disclosure of Invention
The present invention is directed to overcoming the above problems and disadvantages and providing a plastic die steel having high strength and high corrosion resistance, excellent overall properties such as high strength and hardness, high toughness and high corrosion resistance, and an efficient production process.
The purpose of the invention is realized as follows:
a plastic die steel with high strength and high corrosion resistance comprises the following components in percentage by weight: c: 0.20% -0.30%, Si: 0.52% -0.65%, Mn: 0.65-0.80%, P is less than or equal to 0.015%, S is less than or equal to 0.015%, Cr: 11.0% -12.0%, Mo: 0.20% -0.40%, Sn: 0.06% -0.09%, Nb: 0.10% -0.20%, B: 0.001-0.002%, and the balance of Fe and inevitable impurities.
The die steel has the hardness of 37-40HRC, the same-plate hardness difference of less than or equal to 2HRC, the transverse tensile strength of the core of more than or equal to 1020MPa, the yield strength of more than or equal to 860MPa, the elongation of more than or equal to 20 percent and the transverse impact performance (KV)2)≥18J。
The thickness of the die steel plate is 11-180 mm.
The invention adopts the design idea of reducing C, increasing Mn, increasing Nb and B composite action, properly adding Sn and Cr to strengthen the grain boundary and improve the corrosion resistance, and not adding Ni, thereby improving the strength hardness and the corrosion resistance of the plastic die steel, controlling the segregation degree of the plastic die steel to ensure the transverse impact toughness of a final steel plate, saving Ni elements and reducing the cost.
The invention has the following design reasons:
c: carbon can form dispersed alloy carbide in steel, so that the carbon has great influence on strength, plasticity and toughness, weldability and the like and is also a key factor for controlling the strength of martensite. In the case of plastic die steels, a portion of the carbon in the steel enters the matrix of the steel to cause solid solution strengthening, and another portion of the carbon will combine with carbide-forming elements in the alloying elements to form alloyed carbides. In the martensitic stainless steel of the present invention, too high a content of carbon causes various adverse effects such as a reduction in impact and corrosion properties and a severe segregation phenomenon in the core, etc. According to the use requirement of the die steel and the mutual synergy of different properties, the content of the added C is 0.20-0.30%.
Si: silicon is one of important elements for strengthening ferrite, can obviously improve the strength and hardness of steel, can improve the quenching temperature and improves the hardenability. When in a strong oxidizing medium, Si can be elevatedThe corrosion resistance of the steel shows that Si has good Cl resistance like Mo-The higher the Si content in the steel, the more positive the pitting potential, the less susceptible to corrosion. Silicon also reduces the austenite phase region, improves hardenability and basic strength, and is beneficial to secondary hardening. The silicon at the temperature of 540-580 ℃ can improve the dispersion degree of alloy carbide separated out in the tempering process of the die steel and can increase the secondary hardening peak. And meanwhile, the migration rate of carbon is limited, so that precipitated carbide is not easy to grow, the structure of the carbide is more stable, and the chemical stability of the steel is improved. However, the excessive amount of Si makes the spheroidized carbide particles larger in diameter and larger in spacing, and at the same time promotes segregation, resulting in the formation of a band-shaped structure, making the transverse properties lower than the longitudinal properties, so that the Si content is selected to be 0.52-0.65%.
Mn: the Mn-containing steel is a solid solution strengthening element in the steel, the crystal grains are refined, the ductile-brittle transition temperature is reduced, the hardenability is improved, and the Mn-containing steel can change the property and the shape of an oxide formed during the solidification of the steel. Meanwhile, the material has larger affinity with S, and can avoid forming low-melting-point sulfide FeS on a crystal boundary. The die steel adopts the design concept of reducing C and increasing Mn, on one hand, the strength and the hardness of the steel are ensured, on the other hand, the hot-working performance is improved, but in the plastic die steel, the Mn content is not more than 0.80 percent, so the Mn content is selected to be 0.65 to 0.80 percent.
P, S: contributes to improvement of machinability. If the content is too much, serious segregation can be caused, and the homogeneity and the purity of the steel are influenced, but in consideration of the production cost, P is less than or equal to 0.015 percent, and S is less than or equal to 0.015 percent.
Cr: cr can improve the hardenability of the iron-chromium alloy, passivate the steel and endow the martensitic stainless steel with good corrosion resistance and rust resistance, the corrosion potential of Cr is more negative than that of iron, the passivating capability is stronger than that of iron, and in the iron-chromium alloy, the increase of the Cr content can cause the corrosion potential and the critical passivating potential of the alloy to move towards the direction of negative potential. I.e. the higher the chromium content in the alloy, the more susceptible the steel is to passivation. But the cost of excessive Cr is higher, and a proper amount of Sn element is added to replace part of Cr element, so that the Cr content is 11.0-12.0% by selecting and adding the Cr element.
Mo: mo in steel can raise hardenability of steel, at the same time can form special carbide in steel, and can raise secondary hardening capacity and tempering stability of steel, and the molybdenum and carbon are combined, and more fine short rod-like Mo can be separated out during tempering2C carbide plays a great role in improving the tempering stability of the steel. In the martensitic stainless steel of the present invention, in consideration of the cost of the Mo element and the synergistic effect with other alloy elements, the content of Mo is less than 0.4%, and an excessive content of Mo promotes the formation of ferrite, resulting in adverse effects. Therefore, the content of Mo added in the invention is 0.20-0.40%.
Sn: martensitic stainless steel is improved in corrosion resistance mainly by elements such as Cr and Ni, but since Cr and Ni are expensive, the production cost is high. In the invention, a proper amount of Sn is added to strengthen the grain boundary of the plastic die steel, so that the corrosion sensitivity of the grain boundary is greatly reduced, the micro-Sn can refine the structure, the uniform fine grains enable the impurity distribution to be more dispersed, the components to be more uniform, and the point defects and the line defects to be dispersed, thereby preventing the micro-battery from being formed, and further improving the corrosion resistance of the die steel. According to the invention, the addition of a proper amount of Sn element not only saves noble metals such as Cr and Ni, but also saves smelting cost for removing Sn originally, the design idea of adding a proper amount of Sn to reduce Cr and not adding Ni is adopted, the production cost is greatly reduced while the performance of the die steel is improved, the Sn content is controlled to be below 0.09% in the plastic die steel, the surface quality of the steel plate is good, and cracks are not generated. Therefore, the Sn content in the invention is 0.06% -0.09%.
Nb, B: according to the invention, the carbon and nitrogen elements in the steel can be stabilized by the composite addition of Nb and B, the harmful influence of the one-by-one addition on the surface quality of the stainless steel can be compensated by the composite addition, and simultaneously, the composite addition can not only refine the casting blank structure but also refine the hot rolled steel plate structure. According to the invention, B and Nb are added in a composite manner, precipitated phases in the steel are NbC, Nb (C, N) and BN particles, and the precipitated phases are more than those of the NbC, Nb (C, N) and BN particles which are added one by one, so that the precipitated particles are finer, the refining effect is stronger, the fine grain strengthening effect is achieved, and the plasticity and the toughness of the plastic die steel are improved. Therefore, in the invention, Nb is 0.10-0.20%, and B is 0.0001-0.002%.
The second technical scheme of the invention provides a preparation method of plastic die steel with high strength and high corrosion resistance, which comprises the steps of molten iron pretreatment, smelting, LF-RH, continuous casting, slab heating, rolling, straightening, slow cooling and heat treatment;
the slab heating is controlled at 1260-. The cast structure segregation is elongated along the deformation direction in the hot working and rolling process of the steel billet and is gradually consistent with the deformation direction, and the deformed segregation still keeps the appearance of dendrite segregation, so that the appearance that enrichment belts and depletion belts formed by enriching carbon and alloy elements are stacked in succession can be observed, therefore, the slab heating process can improve or eliminate the component nonuniformity formed in the metallurgical process, reduce the microsegregation in the steel billet and provide a good structure appearance foundation for the subsequent hot working. The initial rolling temperature of the plate blank is controlled to be more than or equal to 1050 ℃, a rolling process with high temperature, low speed and large pressure is adopted, the reduction rate of the first five passes is 20-25%, a transverse-longitudinal alternate rolling mode is adopted, the pass reduction is increased on the premise of ensuring the equipment safety, the penetrating power of the rolling force is improved, the deformation penetrates into the center of the blank, coarse dendrites are smashed, and the original defect influence of the continuous casting blank can be effectively reduced. The final rolling temperature is more than or equal to 950 ℃, and the steel plate offline temperature is 300-450 ℃. And (5) immediately stacking and slowing down the line by adopting a mode of laying down and covering up, wherein the slow cooling time is 20-30 h.
And then carrying out heat treatment, specifically: spheroidizing annealing, normalizing and tempering, wherein the plastic die steel adopts a spheroidizing annealing process of three-stage treatment as follows: charging into a furnace at normal temperature, heating to 900-930 ℃ along with the furnace, preserving heat for 1-2h, quickly cooling oil to 450-500 ℃ after discharging, heating to 900-930 ℃ along with the furnace after discharging oil, preserving heat for 1-2h, quickly cooling oil to 450-500 ℃ along with the furnace after discharging oil, heating to 720-750 ℃ along with the furnace after discharging oil, preserving heat for 3-4h, cooling to 400-500 ℃ along with the furnace, discharging from the furnace, and air cooling to room temperature. The invention adopts higher temperature than the traditional annealing to improve the diffusion speed of carbon and other alloy elements in austenite, thereby shortening the furnace time of the steel plate. After the steel plate is heated to a certain temperature, the rapid oil cooling method is adopted, the banded and reticular arrangement of carbide tissues can be effectively improved, and further the diffusion speed of atoms is improved. The isothermal section is a key stage for generating spherical pearlite, the isothermal time is insufficient, the carbon concentration in a steel plate structure is not uniformly distributed, but the secondary carbides are aggregated and combined due to the overlong isothermal time, so that grains grow, and the heat treatment period and the cost are increased.
And then normalizing and tempering heat treatment is carried out. Controlling the normalizing temperature to be 1000-1030 ℃, the heating rate to be 2.0-2.5min/mm, and the net heat preservation time to be 4-6h according to different thicknesses, and cooling the steel plate to the room temperature after the steel plate is taken out of the furnace. The plastic die steel normalizing temperature is higher than 1030 ℃, the acid corrosion resistance is reduced, and meanwhile, the crystal grains are coarse, so that the subsequent structure performance of the steel plate is influenced. The normalizing temperature is too low, so that alloy elements are difficult to be dissolved into austenite, and the structure is not uniform. By adopting the normalizing process, a steel plate can obtain a martensite structure with high proportion after being normalized, so that the uniformity of the structure and the hardness of the steel is greatly improved.
The temperature rise rate in the tempering process is 2.0-2.5min/mm, the tempering temperature is 550-600 ℃, the temperature range can effectively avoid the secondary hardening phenomenon of the plastic die steel, the temperature is kept for 4-6h according to materials with different thicknesses, the stress can be effectively reduced, the tissue banding caused by solid phase change can be controlled, the tissue is uniform and fine, and the polishing performance of the die steel is facilitated.
The invention has the beneficial effects that: the invention adopts the design idea of reducing C and increasing Mn, Nb and B composite action, adding a proper amount of Sn and Cr to strengthen the grain boundary and improve the corrosion resistance, does not add Ni, and is matched with the production of the processes of continuous casting-slab high-temperature homogenization heating-three-stage spheroidizing annealing-normalizing and tempering, so that the corrosion-resistant plastic die steel has the final-state hardness of 37-40HRC, the same-plate hardness difference is less than or equal to 2HRC, the transverse tensile strength of the core is more than or equal to 1020MPa, the yield strength is more than or equal to 860MPa, the elongation is more than or equal to 20 percent, and the transverse impact performance of2) Not less than 18J, the average annual corrosion depth is not more than 0.410mm a under the conditions that the pH value is 6.5-7.2 and the test temperature is 35 ℃ and the continuous spraying is carried out for 24 hours under the conditions that the pH value is 50 g.L-1 sodium chloride solution-1Has excellent corrosion resistance. The corrosion-resistant plastic die steel completely meets the requirements of life and production on the comprehensive performance of the plastic die steel at present, and belongs to high-grade plastic die steel.
Detailed Description
The present invention is further illustrated by the following examples.
According to the component proportion of the technical scheme, the embodiment of the invention carries out molten iron pretreatment, smelting, LF-RH, continuous casting, slab heating, rolling, straightening, slow cooling and heat treatment.
Heating the plate blank at the temperature of 1260-; stacking and slowly cooling the film immediately after the film is off line, wherein the slow cooling time is 20-30 h;
subsequently, a heat treatment is carried out: spheroidizing annealing, normalizing and tempering; the spheroidizing annealing adopts three-stage treatment; the method specifically comprises the following steps: charging into a furnace at normal temperature, heating to 900-930 ℃ along with the furnace, and preserving heat for 1-2 h; rapidly cooling the oil to 450-500 ℃ after discharging; after oil is discharged, the temperature is raised to 900-930 ℃ along with the furnace, the temperature is kept for 1-2h, and the oil is rapidly cooled to 450-500 ℃ after being discharged; heating to 720-750 ℃ along with the furnace after oil is discharged, preserving heat for 3-4h, cooling to 400-500 ℃ along with the furnace, discharging and air cooling to room temperature; then, normalizing is carried out: normalizing at 1000-1030 deg.C, heating rate of 2.0-2.5min/mm, net holding time of 4-6h, and air cooling the steel plate to room temperature after discharging; then tempering is carried out, the tempering temperature is 550-.
The compositions of the steels of the examples of the invention are shown in table 1. The main process parameters of the steel of the embodiment of the invention are shown in Table 2. The main heat treatment process parameters of the steels of the examples of the invention are shown in Table 3. The Rockwell hardness of the steels of the examples of the present invention is shown in Table 4. The tensile and impact properties of the steel cores of the inventive examples are shown in Table 5. The average annual corrosion depth of the steels of the invention is shown in table 6.
TABLE 1 composition (wt%) of steels of examples of the present invention
Figure BDA0002572598020000101
TABLE 2 Main Process parameters of the steels of the examples of the invention
Figure BDA0002572598020000102
TABLE 3 Main Heat treatment Process parameters of the steels of the examples of the invention
Figure BDA0002572598020000111
TABLE 4 Rockwell hardness of steels of examples of the invention
Figure BDA0002572598020000121
The tensile and impact properties of the steel cores of the inventive examples are shown in Table 5.
Figure BDA0002572598020000131
TABLE 6 average annual corrosion depth of steels of examples of the invention
Examples Average annual corrosion depth (mm. a)-1)
1 0.396
2 0.402
3 0.397
4 0.410
5 0.388
6 0.391
7 0.405
8 0.376
9 0.389
10 0.393
Remarking: samples of examples 1 to 10 had the same roughness and had a specification of 50X 4mm at 50 g.L-1The result of the average annual corrosion depth of the sodium chloride solution under the condition that the pH value is 6.5-7.2 and the test temperature is 35 ℃ and the continuous spraying is carried out for 24 hours.
In order to describe the present invention, the above embodiments are properly and fully described by way of examples, and the above embodiments are only used for illustrating the present invention and not for limiting the present invention, and those skilled in the relevant art can make various changes and modifications without departing from the spirit and scope of the present invention, and any modifications, equivalent substitutions, improvements, etc. made by the persons skilled in the relevant art should be included in the protection scope of the present invention, and the protection scope of the present invention should be defined by the claims.

Claims (3)

1. The plastic die steel with high strength and high corrosion resistance is characterized by comprising the following components in percentage by weight: c: 0.20% -0.30%, Si: 0.52% -0.65%, Mn: 0.65-0.80%, P is less than or equal to 0.015%, S is less than or equal to 0.015%, Cr: 11.0% -12.0%, Mo: 0.20% -0.40%, Sn: 0.06% -0.09%, Nb: 0.10% -0.20%, B: 0.001-0.002%, and the balance of Fe and inevitable impurities.
2. The plastic die steel with high strength and high corrosion resistance as claimed in claim 1, wherein the die steel has a hardness of 37-40HRC, a same-plate hardness difference of less than or equal to 2HRC, a core transverse tensile strength of greater than or equal to 1020MPa, a yield strength of greater than or equal to 860MPa, an elongation of greater than or equal to 20%, and a core transverse impact power KV2≥18J。
3. A method for preparing a plastic die steel with high strength and high corrosion resistance according to claim 1 or 2, comprising the steps of molten iron pretreatment, smelting, LF-RH-continuous casting, slab heating, rolling, straightening, slow cooling and heat treatment; the method is characterized in that:
heating the plate blank at the temperature of 1260-; stacking and slowly cooling the film immediately after the film is off line, wherein the slow cooling time is 20-30 h;
subsequently, a heat treatment is carried out: spheroidizing annealing, normalizing and tempering; the spheroidizing annealing adopts three-stage treatment; the method specifically comprises the following steps: charging into the furnace at normal temperature, heating to 900-; rapidly cooling oil to 450-500 ℃ after discharge; after oil is discharged, the temperature is raised to 930 ℃ along with the temperature of 900-; heating the oil to 750 ℃ along with the furnace after oil discharge, preserving the heat for 3-4h, cooling the oil to 500 ℃ along with the furnace, discharging the oil from the furnace, and air cooling the oil to room temperature; then, normalizing is carried out: normalizing at 1000-1030 ℃, heating rate of 2.0-2.5min/mm, net heat preservation time of 4-6h, and air cooling the steel plate to room temperature after discharging; then tempering is carried out, the tempering temperature is 550-.
CN202010644708.6A 2020-07-07 2020-07-07 Plastic die steel with high strength and high corrosion resistance and preparation method thereof Active CN111826589B (en)

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CN116479333A (en) * 2023-04-28 2023-07-25 鞍钢股份有限公司 Die steel with high thermal fatigue resistance and high temperature impact toughness and preparation method thereof
CN116334496B (en) * 2023-04-28 2024-01-09 鞍钢股份有限公司 Die steel with fine eutectic carbide and preparation method thereof
CN116479333B (en) * 2023-04-28 2024-01-09 鞍钢股份有限公司 Die steel with high thermal fatigue resistance and high temperature impact toughness and preparation method thereof

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