CN116083801A - High-uniformity high-mirror polishing performance die steel and preparation method thereof - Google Patents

Abstract

The invention discloses a mold steel with high uniformity and high mirror polishing performance and a preparation method thereof, which belongs to the technical field of tool and mold steels and solves the problems of serious carbide segregation and poor structure uniformity in plastic mold steels in the prior art. The components of the mold steel with high uniformity and high mirror polishing performance include: C: 0.10% ~ 0.30%, Si: ≤ 1%, Mn: ≤ 1%, Cr: 10.0% ~ 14.0%, Ni: 0.2% ~ 2.0%, Mo: 0.5% to 1.0%, V: 0.005% to 1.00%, N: 0.15% to 0.50%, and the balance is Fe and unavoidable impurities. The die steel with high uniformity and high mirror polishing performance of the invention has good uniformity, excellent cutting performance and excellent corrosion resistance.

Description

A kind of mold steel with high uniformity and high mirror polishing performance and preparation method thereof

technical field

The invention relates to the technical field of tool and die steel, in particular to a die steel with high uniformity and high mirror polishing performance and a preparation method thereof.

Background technique

Corrosion-resistant plastic mold steel, as a high-end product in mold steel, is mainly used for special engineering plastics with high forming temperature and plastics containing flame retardants. The raw materials will decompose and produce a large amount of corrosive gases in the molten state, such as hydrogen chloride and hydrogen fluoride. And sulfur dioxide, etc., have a corrosive effect on the plastic mold cavity used, resulting in a reduction in the service life of the mold. Therefore, such molds should have certain corrosion resistance. At present, the commonly used corrosion-resistant plastic mold steels are 4Cr13, 9Cr18, etc., which belong to martensitic stainless steel. However, this type of steel still has problems such as serious carbide segregation, poor structure uniformity, and insufficient corrosion resistance. It is difficult to meet the needs of ultra-high-precision plastic products for high polishing performance and corrosion resistance, which restricts the quality stabilization of this type of steel. And market high-end, its performance needs to be further improved.

Contents of the invention

In view of the above, the present invention aims to provide a mold steel with high uniformity and high mirror polishing performance and a preparation method thereof, which are used to solve the problem of serious carbide segregation and poor tissue uniformity; Corrosion and wear resistance cannot be taken into account at the same time.

The purpose of the present invention is mainly achieved through the following technical solutions:

The invention provides a mold steel with high uniformity and high mirror polishing performance. The components of the mold steel with high uniformity and high mirror polishing performance include: C: 0.10% to 0.30%, Si: ≤ 1%, Mn: ≤ 1 %, Cr: 10.0% to 14.0%, Ni: 0.2% to 2.0%, Mo: 0.5% to 1.0%, V: 0.005% to 1.00%, N: 0.15% to 0.50%, and the balance is Fe and unavoidable Impurities.

Further, the components of the mold steel with high uniformity and high mirror polishing performance are also added with one or several elements selected from the following elements, in terms of mass percentage, including: Cu≤0.5%, Nb≤0.05%, Co≤0.5%, Rare earth elements ≤0.05%.

Further, the components of the mold steel with high uniformity and high mirror polishing performance include: C: 0.11% to 0.30%, Si: 0.20% to 0.80%, Mn: 0.20% to 0.80%, Cr: 10.2% to 13.7% by mass percentage %, Ni: 0.2% to 1.9%, Mo: 0.5% to 1.0%, V: 0.005% to 0.95%, N: 0.15% to 0.50%, and the balance is Fe and unavoidable impurities.

The present invention also provides a method for preparing a mold steel with high uniformity and high mirror polishing performance, which is used to prepare the above mold steel with high uniformity and high mirror polishing performance, including:

Step 1, smelting and pouring to obtain the electrode blank, and performing slow cooling or thermal insulation annealing on the electrode blank;

Step 2. The electrode blank is remelted in a pressurized electroslag furnace, cast into a steel ingot, and the steel ingot is subjected to slow cooling or thermal insulation annealing;

Step 3, forging the steel ingot to obtain a forging billet;

Step 4, carrying out dispersion treatment to the forged billet;

Step 5, the steel after the dispersion treatment is annealed;

Step 6: Quenching the annealed steel and then tempering; or quenching the annealed steel, cryogenically treating it, and then tempering the annealed steel.

Further, in step 3, the forging includes: fully heating the steel ingot and then forging after keeping it warm; the heating temperature is controlled at 1160-1200° C., and the holding time is 10-15 hours.

Further, in step 3, the initial forging temperature is 1160-1200°C, and the final forging temperature is 830-860°C.

Further, in step 4, the dispersion treatment includes: heating the forging billet to the first holding temperature of 980-1020°C for 1-2 hours, and then water cooling to room temperature; 4h, air-cooled to room temperature.

Further, in step 5, the annealing treatment includes: heating the steel after the dispersion treatment to 850±10°C, and keeping it for 1-2 hours; cooling the furnace to 650±10°C, keeping it for 1-2 hours, and then cooling the steel to below 400°C out of the oven.

Further, in step 6, the tempering treatment is performed at 150-520°C.

Further, in step 6, the structure of the tempered steel is martensite + fine dispersed carbide and carbonitride precipitates, the martensite lath is uniform, and no obvious network segregation and strip segregation are seen.

Compared with the prior art, the beneficial effects of the present invention are as follows:

a) The mold steel with high uniformity and high mirror polishing performance of the present invention adopts low C, adds appropriate amount of Cr, Mo, V and N elements, reduces carbide and structure segregation, and under the appropriate dispersion treatment and quenching+tempering process , Obtain the structure of martensite + fine dispersed carbide and carbonitride precipitates, the martensite lath is uniform, no obvious network segregation and strip segregation, so as to obtain high uniformity, high mirror polishing performance and excellent corrosion resistance performance tool steel.

b) The mold steel with high uniformity and high mirror polishing performance prepared by adopting the composition and method of the present invention has good comprehensive mechanical properties, and the uniformity of the steel after annealing treatment is good, and the cutting performance is excellent. The structure of the tempered steel is uniform, and the tempered steel has high tempering hardness, high impact toughness and low roughness, which meets the requirements of mirror polishing performance and has excellent corrosion resistance.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Description of drawings

The drawings are for the purpose of illustrating specific embodiments only and are not to be considered as limitations of the invention, and like reference numerals refer to like parts throughout the drawings.

Fig. 1 is the tempered structure 50 * of embodiment 2;

Fig. 2 is the tempered structure 100 * of comparative example 1;

Fig. 3 is the tempered structure 500× of the steel of embodiment 1 after tempering at 240°C;

Fig. 4 is the tempered structure 500× of the steel of comparative example 1 after being tempered at 240°C;

Fig. 5 is the tempered structure 500× of the steel of embodiment 1 after being tempered at 500°C;

Fig. 6 is the tempered structure 500× of the steel of Comparative Example 1 after being tempered at 500°C.

Detailed ways

The preferred embodiments of the present invention will be specifically described below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to explain the principles of the present invention.

The invention provides a mold steel with high uniformity and high mirror polishing performance. The components of the mold steel with high uniformity and high mirror polishing performance include: C: 0.10% to 0.30%, Si: ≤ 1%, Mn: ≤ 1 %, Cr: 10.0% to 14.0%, Ni: 0.2% to 2.0%, Mo: 0.5% to 1.0%, V: 0.005% to 1.00%, N: 0.15% to 0.50%, and the balance is Fe and unavoidable Impurities.

The effect and consumption selection of contained component in the present invention are described in detail below:

C: The carbon content in the steel determines the hardness of the steel matrix. For tool and die steel, part of the carbon dissolves into the matrix for solid solution strengthening, and the other part of carbon combines with strong carbide-forming elements to form alloy carbides. C forms alloy carbides with some alloying elements to improve the hardness and wear resistance of steel, and the uniformly dispersed and precipitated alloy carbides and tempered martensite affect the corrosion resistance of steel. In order to obtain higher hardness, wear resistance and corrosion resistance, the carbon content is controlled at 0.10%-0.30% in the present invention.

Si: Silicon is added as a reducing agent and deoxidizer in the steelmaking process, which has a significant effect on improving corrosion resistance. However, too high Si content will not only reduce the toughness of the steel, but also promote the generation of segregation. Therefore, the silicon content is generally Control it below 1%.

Mn: Manganese is an element that improves the hardenability of steel, so that the core can also achieve the expected mechanical properties. An appropriate amount of manganese can also effectively improve the strength, hardness and toughness of the steel, eliminate the harmful effects of sulfur and oxygen on the steel, improve the thermal processing performance of the steel, and improve the cold and brittle tendency of the steel. However, segregation is likely to occur if the manganese content is too high, so the Mn content is controlled below 1.0% in the present invention.

Ni: Nickel is an important hardenability-enhancing element, which can improve the strength and toughness of steel in some steels. The addition of Ni can improve the passivation tendency of Fe-Cr alloy, not only can improve the corrosion resistance of steel in acid and alkali medium, but also has corrosion resistance to atmosphere and salt. The determined Ni content in the steel of the present invention is 0.2%-2.0%.

Cr: As the main constituent element of corrosion-resistant steel, chromium can not only improve the hardenability of Fe-Cr alloy, but also guarantee the corrosion resistance and stainlessness of steel. However, if the Cr content is too high, the formation of high-temperature ferrite and reticulated carbides will be promoted, which will affect the service performance of the steel. Therefore, the present invention controls the Cr content at 10.0%-14.0%.

Mo: Molybdenum in steel can improve the hardenability of steel. At the same time, Mo combines with C and N elements to produce carbides and carbonitrides, which can improve the secondary hardening ability and tempering stability of steel. Mo is also the main element for improving corrosion resistance, but too high Mo content will promote the formation of ferrite and reduce the strength and toughness of steel. The present invention further improves the corrosion resistance of steel through Mo-Ni compounding, and the Mo content is controlled at 0.5% to 1.0%.

V: Vanadium can reduce the overheating sensitivity of steel. A small amount of V element can refine the grains, and promote the dispersion and precipitation of carbides after proper heat treatment, which can strengthen the secondary hardening. However, too high V content will increase the formation probability of primary carbides in the steel and affect the toughness of the steel. The present invention controls the V content at 0.005% to 1.00%.

N: Nitrogen is an interstitial solid solution element, which can produce a significant solid solution strengthening effect and improve the corrosion resistance of steel. In the present invention, by substituting part of C with N, the coarse carbides formed due to the combination of excessive C content and Cr can be reduced, which is detrimental to the structure uniformity and polishing performance. High hardness is obtained by N alloying in order to improve polishing performance. At the same time, a small amount of N combines with Cr and V to precipitate fine and dispersed Cr ₂ N and NV carbides during the tempering process, which has a precipitation strengthening effect and makes the steel obtain high hardness, thereby improving the polishing performance and improving the steel's resistance to corrosion. grinding performance. The present invention utilizes the concept of nitrogen distribution strengthening, and controls N at 0.15%-0.50%.

P: Phosphorus forms microscopic segregation when the molten steel solidifies, and then segregates at the grain boundary when heated at the austenitizing temperature, which significantly increases the brittleness of the steel. The present invention controls the content of P below 0.030%, and the lower the content, the better.

S: Sulfur is an unavoidable impurity, forms FeS, and brings hot embrittlement to steel. The present invention controls the S content below 0.030%, and the lower the content, the better.

In order to further improve the overall performance of the above-mentioned mold steel with high uniformity and high mirror polishing performance, the components of the mold steel with high uniformity and high mirror polishing performance can also be added with one or more elements selected from the following elements, by mass percentage, including: Cu≤0.5%, Nb≤0.05%, Co≤0.5%, rare earth elements≤0.05%.

The role and proportioning basis of the above-mentioned elements are as follows:

Cu: Copper is an austenite-forming element, which can improve corrosion resistance and cause secondary hardening effect. However, if the copper content is too high, there will be a tendency of overheating sensitivity. The present invention controls copper to ≤0.5%.

Nb: Niobium can refine the grains, increase the grain coarsening temperature, reduce the overheating sensitivity and temper brittleness of the steel, and under certain conditions, improve the strength and toughness of the steel. In the present invention, ≤0.05% niobium is added.

Co: Cobalt is an austenite forming element that improves tempering stability. Cobalt can improve the strength properties of steel by solid solution strengthening, and at the same time, cobalt can promote the second phase dispersion precipitation strengthening effect to obtain ultra-high strength and good comprehensive mechanical properties. The present invention controls the cobalt content to ≤0.5%.

Rare earth elements: rare earth elements can refine the as-cast structure of steel. For large-scale steel products, large ingot-shaped steel ingots are required for smelting. If necessary, a small amount of rare earth elements can be added to reduce the segregation of the as-cast structure and obtain a uniform solidified structure. At the same time, rare earth elements can improve the plasticity and impact toughness of steel, further strengthen the beneficial effects of silicon and manganese, and enhance the oxidation resistance of the alloy. In the present invention, ≤0.05% of rare earth elements are added.

In order to further improve the overall performance of the mold steel with high uniformity and high mirror polishing performance, the components of the mold steel with high uniformity and high mirror polishing performance may include: C: 0.11% to 0.30%, and Si: 0.20% to 0.80%. , Mn: 0.20% to 0.80%, Cr: 10.2% to 13.7%, Ni: 0.2% to 1.9%, Mo: 0.5% to 1.0%, V: 0.005% to 0.95%, N: 0.15% to 0.50%, and more The amount is Fe and unavoidable impurities.

The present invention also provides a method for preparing the mold steel with high uniformity and high mirror polishing performance, including:

Step 1, smelting and pouring to obtain the electrode blank, and slowly cooling or 800-900°C heat preservation annealing treatment on the electrode blank;

Step 2. The electrode blank is remelted in a pressurized electroslag furnace, cast into a steel ingot, and the steel ingot is subjected to slow cooling or heat preservation and annealing at 800-900°C;

Step 3, forging the steel ingot to obtain a forging billet;

Step 4, carrying out dispersion treatment to the forged billet;

Step 5, the steel after the dispersion treatment is annealed;

Step 6: Quenching the annealed steel and then tempering; or quenching the annealed steel, cryogenically treating it, and then tempering the annealed steel.

Specifically, in the above-mentioned step 1, the smelting can adopt converter, electric furnace, induction furnace+out-of-furnace refining.

Specifically, in the above step 3, forging includes: forging the steel ingot after being fully heated and kept warm. Considering that the heating temperature is too high or the holding time is too long, the abnormal structure of the steel ingot will affect the subsequent processing and use performance of the steel, and the high heating temperature and the long holding time waste energy; the heating temperature is too low or the holding time is too low. If it is too short, it will not achieve the effect of homogenizing the structure and carbides. Therefore, the heating temperature is controlled at 1160-1200 ° C, and the holding time is 10-15 hours.

Specifically, in the above step 3, considering that too high initial forging temperature may cause overburning and overheating, too low initial forging temperature will shorten the forging operation time, reduce the forging temperature range, and cause forging difficulties; if the final forging temperature is too high, after forging The grain grows rapidly at high temperature, resulting in coarse grain of the forging, which reduces the mechanical properties of the forging, while the final forging temperature is too low, the plasticity of the forging is poor, the deformation is difficult, and the internal stress increases, resulting in cracks in the forging. Therefore, the control is always The forging temperature is 1160-1200°C, and the final forging temperature is 830-860°C.

Specifically, in the above step 4, the dispersion treatment includes: heating the forged billet to the first holding temperature of 980-1020°C for 1-2 hours, and then water cooling to room temperature; ~4h, air-cooled to room temperature.

Specifically, in the above step 4, the effect of the first heat preservation is to make the steel reach the austenitization temperature, and the carbides are dissolved and refined. Considering that the first time heat preservation temperature is too high and the heat preservation time is too long, the structure and Grain coarsening; too low holding temperature and too short holding time can hardly achieve the effect of carbide dissolution and refinement. Therefore, control the first holding temperature to 980-1020°C and hold for 1-2 hours.

Specifically, in the above step 4, the function of the second heat preservation is to obtain a granular pearlite structure with ferrite as the matrix and uniformly dispersed granular carbides. Considering that the second holding temperature is too high or too low to exceed the pearlite formation temperature range, the holding time is too long and the tissue is thick and the time is too short to achieve the effect of pearlite dispersion. Therefore, the second holding temperature is controlled at 630°C. ~670°C, keep warm for 2~4h.

Specifically, in the above step 5, the effect of the annealing treatment is to reduce the hardness of the steel, improve the machinability and process performance, eliminate or reduce internal stress, so as to prevent deformation and cracking during processing, and refine the grains, uniform chemical Composition and Organization. The annealing treatment includes: heating the steel after the dispersion treatment to 850±10°C and holding it for 1-2 hours; cooling it in the furnace to 650±10°C and holding it for 1-2 hours, and then cooling it to below 400°C and leaving the furnace. Granular pearlite is the most ideal annealed structure state, which can not only ensure the uniformity of the structure, but also have low hardness, which is convenient for subsequent cutting. According to the structural transformation and phase transformation characteristics of the steel, it is necessary to carry out specific austenitization of the steel at 850±10°C. In this temperature range, some undissolved carbides remain as non-spontaneous nucleation points for the decomposition of supercooled austenite, forming Pearlite crystal nucleation; followed by supercooled austenite decomposition in the temperature range of 650±10°C to obtain a granular pearlite structure with ferrite as the matrix uniformly dispersed with granular carbides; pearlite is completed after cooling to 400°C Transformed and stabilized, out of the oven.

Specifically, in the above step 6, the quenching treatment includes: keeping the temperature at 950-1050° C. for 0.5-2 hours, and cooling the furnace with water or oil to room temperature.

Specifically, in the above step 6, the cryogenic treatment is to reduce the content of retained austenite in the steel after quenching, and improve the strength and hardness of the steel. The cryogenic treatment includes: holding at -73° C. to -84° C. for 0.5 to 2 hours.

Specifically, in the above step 6, the tempering treatment may be performed at 150-520°C.

Specifically, in the above step 5, the uniformity of the steel after the annealing treatment is good, and the hardness difference at different positions is small, for example, the hardness difference at different positions is within 7HB.

Specifically, in the above step 5, the hardness of the steel after the annealing treatment is ≤185HB, and the cutting performance is excellent.

Specifically, in the above step 6, the structure of the tempered steel is martensite + fine dispersed carbide and carbonitride precipitates, the martensite lath is uniform, and no obvious network segregation and strip segregation are seen. , the structure is more uniform, the size of carbides and carbonitrides is below 1 μm, and they are finer and dispersed on the matrix structure. The uniform structure is beneficial to the improvement of various performances of steel.

Specifically, in the above step 6, the tempered steel has a higher tempering hardness, for example, when tempering at 150°C, the hardness reaches above 54HRC (for example, 54.8～57.5HRC); when tempering at 200°C, the hardness reaches Above 55.5HRC (such as 55.7～58.5HRC); when tempering at 300℃, the hardness reaches above 53HRC (such as 53.4～57HRC); when tempering at 350℃, the hardness reaches above 53HRC (such as 53.2～55.5HRC); when tempering at 400℃ When tempering at 500℃, the hardness reaches above 56.5HRC (such as 56.5～60HRC).

Specifically, in the above step 6, the tempered steel has relatively high impact toughness, for example, after quenching at 1030°C, the impact toughness after tempering at 240°C is Aku≥25J (for example, 25.1-32J), quenching at 1030°C, The impact toughness Aku after tempering at 500°C is greater than or equal to 9.5J (for example, 9.6-12J).

Specifically, in the above step 6, the roughness of the tempered steel is low, and the polishing performance of Ra 0.01 μm level can be obtained, so as to realize the mirror polishing performance requirement.

Specifically, in the above step 6, the tempered steel was subjected to a 120h salt spray corrosion test using 5% NaCl solution, which had a low corrosion rate and corrosion weight loss, and excellent corrosion resistance. For example, the corrosion rate is below 0.009g/m ² ·h, and the annual corrosion depth is below 0.0095mm/a.

Compared with the prior art, the mold steel with high uniformity and high mirror polishing performance of the present invention adopts low C, adds appropriate amount of Cr, Mo, V and N elements, reduces carbide and structure segregation, and can be processed under appropriate dispersion treatment and quenching +Under the tempering process, the structure of martensite + fine dispersed carbide and carbonitride precipitates is obtained, the martensite lath is uniform, and there is no obvious network segregation and strip segregation, so as to obtain high uniformity and high mirror polishing High performance and excellent corrosion resistance tool steel.

The mold steel with high uniformity and high mirror polishing performance prepared by adopting the composition and method of the invention has good comprehensive mechanical properties, and the steel material after annealing treatment has good uniformity and excellent cutting performance. The structure of the tempered steel is uniform, and the tempered steel has high tempering hardness, high impact toughness and low roughness, which meets the requirements of mirror polishing performance and has excellent corrosion resistance.

Examples 1-6

Embodiments 1-6 of the present invention provide a mold steel with high uniformity and high mirror polishing performance and a preparation method thereof. The components of the steel in Embodiments 1-4 include: C: 0.10% to 0.30%, Si: ≤1%, Mn: ≤1%, Cr: 10.0%～14.0%, Ni: 0.2%～2.0%, Mo: 0.5%～1.0%, V: 0.005%～1.00%, N: 0.15%～0.50%, The balance is Fe and unavoidable impurities.

Specifically, one or several elements selected from the following elements can also be added in the steel of Examples 5-6, in terms of mass percentage, including: Cu≤0.5%, Nb≤0.05%, Co≤0.5%, rare earth elements ≤0.05%.

The compositions of the steels of Examples 1-6 are shown in Table 1 below.

The preparation method of the steel of embodiment 1-6 comprises:

(1) casting molten steel into ingots;

(2) Heating the ingot to 1160-1200°C, holding it for 10-15 hours, then forging to make bars of Φ130mm and Φ170mm; the initial forging temperature is 1160-1200°C, and the final forging temperature is 830-860°C;

(3) Carry out dispersion treatment on the bar: heat to the first holding temperature of 980-1020°C for 1-2 hours, then water-cool to room temperature; then hold at the second holding temperature of 630-670°C for 2-4 hours, and air-cool to room temperature;

(4) Then perform annealing treatment: heat the steel after dispersion treatment to 850±10°C for 1 to 2 hours, slowly cool to 650±10°C for heat preservation, and leave the furnace when the furnace is cooled below 400°C; process it into a sample and quench it , Cryogenic, tempering treatment. Among them, quenching at 950-1050°C and tempering at 150-520°C. Its performance is shown in Table 2-7.

It can be seen from Tables 2 to 7 that the steel of the present invention has excellent structure uniformity, and simultaneously has good polishability, toughness and corrosion resistance.

Specifically, as shown in Table 2, after the steel is forged and annealed, three positions of the edge, quarter and center of the comparative steel of Examples 1-6 are selected for annealing hardness detection. The steel of the present invention and the comparison Compared with steel, the annealed hardness after annealing is ≤185HB, and the annealed hardness difference at each position is small (the hardness difference at different positions is within 7HB), and the cutting performance is excellent and has good uniformity.

Specifically, after quenching at the same temperature and tempering at different temperatures, the tempered structures of the comparative steels of Examples 1-6 are all martensite + carbonitrides. Figure 1 shows the tempered structure of Example 2 at 50×, and Figure 2 The tempered structure of Comparative Example 1 is 100×, and the comparative example steel has macroscopic structure segregation and obvious large-grained carbides. Fine and evenly distributed, with a more uniform texture. Figure 3 is the tempered structure 500× of the steel in Example 1 after tempering at 240°C, and Figure 4 is the tempered structure 500× of the steel in Comparative Example 1 after being tempered at 240°C; Figure 5 is the tempered structure of the steel in Example 1 The tempered structure after tempering at 500°C is 500×, and Fig. 6 shows the tempered structure 500× of the steel in Comparative Example 1 after being tempered at 500°C.

Specifically, as shown in Table 3 and Table 4, after quenching at the same temperature and tempering at different temperatures, the steel of the present invention and the comparative steel have higher tempering hardness when tempered above 150°C.

Specifically, as shown in Table 5, after quenching at the same temperature and tempering at different temperatures, the steel of the present invention has higher impact toughness than the comparative steel, and can better meet the requirement of high toughness.

Specifically, as shown in Table 6, after quenching at the same temperature, tempering at 240°C, and using a surface roughness tester to detect the surface roughness, the steel of the present invention has a lower roughness than the steel of the comparative example, and can obtain Ra 0.01 The polishing performance of μm level meets the requirements of mirror polishing performance.

Specifically, as shown in Table 7, after quenching at the same temperature, tempering at 240°C, and using 5% NaCl solution for 120h salt spray corrosion experiment, the steel of the present invention has lower corrosion rate and corrosion weight loss than the steel of the comparative example. The corrosion resistance is more excellent, which can meet the requirements of corrosion resistance.

Table 1 Chemical composition (%)

Table 2 embodiment and the annealing hardness of contrast steel

Table 3 Hardness values of the examples and comparison steels quenched at 1030°C - 73°C cryogenically tempered at different temperatures

Table 4 Hardness values of the examples and comparison steels quenched at 1050°C - 73°C cryogenically tempered at different temperatures

Table 5 Impact toughness of the examples and comparison steels quenched at 1030°C and tempered at different temperatures

Table 6 The polishing properties of the examples and comparative examples quenched at 1030°C and tempered at 240°C

Table 7 Corrosion Resistance of Examples and Comparative Steels Quenched at 1030°C and Tempered at 240°C

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention.

Claims (10)

1. The high-uniformity high-mirror-finish-performance die steel is characterized by comprising the following components in percentage by mass: c:0.10 to 0.30 percent, si: less than or equal to 1 percent, mn: less than or equal to 1 percent, cr:10.0 to 14.0 percent of Ni:0.2 to 2.0 percent, mo:0.5 to 1.0 percent, V:0.005% -1.00%, N:0.15 to 0.50 percent, and the balance of Fe and unavoidable impurities.

2. The high-uniformity high-mirror-finish mold steel according to claim 1, wherein the components of the high-uniformity high-mirror-finish mold steel further comprise one or more selected from the following elements in mass percent: cu is less than or equal to 0.5 percent, nb is less than or equal to 0.05 percent, co is less than or equal to 0.5 percent, and rare earth element is less than or equal to 0.05 percent.

3. The high-uniformity high-mirror-finish mold steel according to claim 1, wherein the high-uniformity high-mirror-finish mold steel comprises the components in mass percent: c:0.11 to 0.30 percent, si:0.20 to 0.80 percent of Mn:0.20 to 0.80 percent, cr:10.2 to 13.7 percent of Ni:0.2 to 1.9 percent of Mo:0.5 to 1.0 percent, V:0.005% -0.95%, N:0.15 to 0.50 percent, and the balance of Fe and unavoidable impurities.

4. A method for preparing a high-uniformity high-specular finish performance die steel, characterized by being used for preparing the high-uniformity high-specular finish performance die steel according to any one of claims 1 to 3, comprising:

step 1, smelting and pouring to obtain an electrode blank, and carrying out slow cooling or heat preservation annealing treatment on the electrode blank;

step 2, remelting the electrode blank by a pressurizing electroslag furnace, casting into a steel ingot, and carrying out slow cooling or heat preservation annealing treatment on the steel ingot;

step 3, forging the steel ingot to obtain a forging stock;

step 4, performing dispersion treatment on the forging stock;

step 5, annealing the steel subjected to the dispersion treatment;

step 6, quenching the annealed steel, and tempering; or quenching the annealed steel, performing deep cooling treatment, and then performing tempering treatment.

5. The method according to claim 4, wherein in the step 3, forging includes: fully heating and preserving heat of the steel ingot, and forging; the heating temperature is controlled to 1160-1200 ℃, and the heat preservation time is 10-15 h.

6. The method according to claim 4, wherein in the step 3, the initial forging temperature is 1160 to 1200 ℃ and the final forging temperature is 830 to 860 ℃.

7. The method according to claim 4, wherein in the step 4, the dispersing treatment comprises: heating the forging stock to 980-1020 ℃ for heat preservation for 1-2 h, and then cooling to room temperature; then preserving heat for 2-4 hours at the temperature of 630-670 ℃ for the second time, and cooling to room temperature.

8. The method according to claim 4, wherein in the step 5, the annealing treatment comprises: heating the steel subjected to the dispersion treatment to 850+/-10 ℃, and preserving heat for 1-2 hours; furnace cooling to 650+/-10 ℃, preserving heat for 1-2 h, and then discharging after furnace cooling to below 400 ℃.

9. The method according to claim 4, wherein in the step 6, tempering is performed at 150 to 520 ℃.

10. The method according to any one of claims 4 to 9, wherein in step 6, the tempered steel material has a structure of martensite+fine dispersed carbide and carbonitride precipitated phases, and the martensite laths are uniform, and no significant network segregation and no band segregation are observed.

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