Low-alloy wear-resistant steel for wet grinding working condition and preparation method of low-alloy wear-resistant steel

Abstract

The invention discloses low-alloy wear-resistant steel for a wet grinding working condition, which is characterized by comprising the following material components in percentage by mass: 0.3 to 0.35 percent of C, 1.0 to 1.3 percent of Cr, less than or equal to 0.25 percent of Ni, 0.4 to 0.5 percent of Mo, 0.8 to 1.2 percent of Si, 0.8 to 1.2 percent of Mn, 0.2 to 0.3 percent of Cu, less than or equal to 0.04 percent of Nb, 0.003 percent of B, less than or equal to 0.025 percent of S, less than or equal to 0.025 percent of P and the balance of iron and inevitable impurities. The invention further discloses a corresponding preparation method, the prepared low-alloy wear-resistant steel is mainly composed of lath-shaped martensite and needle-shaped martensite in structure, the grain size is small, balance of hardness and toughness is achieved, meanwhile, the excellent wet-grinding wear-resistant performance is achieved, and the low-alloy wear-resistant steel can be used for heavy mechanical equipment in the field of wet grinding.

Description

Technical Field

[0001] The invention belongs to the technical field of wear-resistant steel, and in particular relates to a low-alloy wear-resistant steel for wet grinding conditions and a preparation method thereof. Background Art

[0002] Wear-resistant materials are a special type of material. They are mostly used in situations where wear exists, such as mechanical parts in mining machinery, engineering machinery, and powder equipment that interact with materials such as soil, sand, ore, rock, and cement.

[0003] Low alloy steel is a type of steel with a low alloy content. Its total alloy content is ≤5%, and its carbon content w (C) is generally between 0.30% and 0.50%. Elements often added to this type of alloy steel include manganese, silicon, chromium, nickel, molybdenum, tungsten, etc. It has excellent strength, toughness, wear resistance and corrosion resistance, and is not expensive, so it has a wide range of uses.

[0004] However, the current low alloy wear-resistant steel has the following problems:

[0005] (1) Poor corrosion resistance

[0006] After searching, CN114032438A discloses a low-alloy wear-resistant steel, which is mainly composed of C, Si, Mn, and Cr elements. The chemical composition weight percentage of the wear-resistant steel is: C0.08%~0.13%, Si1.2%~1.6%, Mn0.3%~0.6%, Cr10%~13%, Ni0.6%~0.8%, Mo0.2%~0.4%, Cu0.2%~0.4%, S / P<0.035, and the rest is Fe. This invention improves the impact toughness of the steel while ensuring hardness by adding grain refiners and optimizing austenite forming conditions, but the corrosion resistance is weak, which is why this type of low-alloy wear-resistant steel cannot be used in high-corrosion scenarios.

[0007] (2) Poor wear resistance

[0008] Wet grinding conditions put forward more stringent conditions for the use of wear-resistant steel. Wear-resistant steel will be subject to the following types of wear during the operation of the wet mill: high-stress impact wear, high-stress wear, corrosive wear (including oxidation wear and electrochemical corrosion wear) and surface fatigue wear. However, there is currently no low-alloy wear-resistant steel or corresponding mature material that can withstand the above wear environment and cannot be used in wet grinding conditions. Summary of the invention

[0009] In view of the shortcomings of the prior art, the present invention proposes a low alloy wear-resistant steel for wet grinding conditions and a preparation method thereof. By adding Cu and Cr elements, a dense oxide film and a corrosion-resistant layer are formed on the surface of the base steel material, so that the alloy steel has excellent wet grinding and wear resistance and can effectively resist wear and corrosion in a wet environment. The added Cu and Nb elements cooperate to meet the requirements for corrosion resistance under wet grinding conditions.

[0010] The first aspect of the present invention is to provide a low-alloy wear-resistant steel for wet grinding conditions, wherein the material composition according to mass percentage is: C is 0.3%-0.35%, Cr is 1.0%-1.3%, Ni≤0.25%, Mo is 0.4%-0.5%, Si is 0.8%-1.2%, Mn is 0.8%-1.2%, Cu is 0.2%-0.3%, Nb≤0.04%, B is 0.003%, S≤0.025%, P≤0.025%, and the balance is iron and unavoidable impurities.

[0011] Preferably, the mass percentage of Cu is 0.25%.

[0012] Preferably, the mass percentage of Nb is 0.02%.

[0013] Preferably, the mass percentage of Cr is 1.2%.

[0014] A second aspect of the present invention provides a method for preparing low alloy wear-resistant steel for wet grinding conditions, comprising the following steps:

[0015] S1, determining the amount of raw materials for preparing the low alloy wear-resistant steel, wherein the raw materials include scrap steel, pig iron, scrap copper, ferrochrome, ferrosilicon, ferromanganese, ferromolybdenum, nickel block, ferroniobium and a carburizer;

[0016] S2, adding the scrap steel and a first mass percentage of a recarburizer into a smelting furnace to melt the scrap steel;

[0017] S3, after detecting that the melting amount of the scrap steel exceeds a first threshold, adding other raw materials except the scrap steel for comprehensive smelting;

[0018] S4, detecting that the comprehensive smelting is finished, adding a proper amount of element B and deoxidizing agent Al to deoxidize the smelting product;

[0019] S5, after deoxidation is completed, the smelted product is controlled to be discharged from the smelting furnace within a certain temperature range, and rapid hot pouring is performed immediately after being discharged from the smelting furnace;

[0020] S6, cooling the casting formed after pouring to below the first temperature for heat treatment to obtain low alloy wear-resistant steel for wet grinding conditions.

[0021] Preferably, S2 comprises: adding the scrap steel and 50% by mass of a recarburizer into a smelting furnace to melt the scrap steel; wherein, after adding into the smelting furnace, firstly preheating with low power, and then melting the scrap steel with high power after the current of the smelting furnace is stabilized.

[0022] Preferably, S3 includes: when it is detected that the melted amount of the scrap steel exceeds half of the total amount of the scrap steel, pig iron, scrap copper, ferrochrome, ferromanganese, ferrosilicon, ferromolybdenum, nickel blocks, ferroniobium and another 50% by mass percentage of carburizer are added in sequence to continue smelting.

[0023] Preferably, the furnace temperature ranges from 1580°C to 1600°C.

[0024] Preferably, the first temperature is 200°C.

[0025] Preferably, the heat treatment comprises:

[0026] (1) Heating: heating the casting formed after pouring to a heating temperature of 860° C. to 910° C. at a heating rate not exceeding 80° C. / h;

[0027] (2) heat preservation: keeping the casting formed after pouring at the heating temperature for at least 60 minutes to ensure that the alloy elements are uniformly dissolved in the iron matrix of the casting;

[0028] (3) Quenching: immersing the casting formed after the heat preservation into an oil medium and cooling it at a rate of 50° C. / min until it reaches room temperature;

[0029] (4) Tempering: The casting formed after quenching is subjected to tempering treatment to reduce the hardness of the casting and improve its toughness; the casting formed after pouring is heated again to 200°C-230°C at a heating rate not exceeding 80°C / h, maintained at this temperature for 1 hour, and then cooled to room temperature in air.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1. Adding an appropriate amount of 0.0014% B to improve the hardenability of the steel, thereby obtaining a better effect during the quenching process. Specifically, the prepared low-alloy wear-resistant steel has a structure dominated by lath martensite and needle martensite and containing a small amount of bainite after quenching and tempering, and the grain size is small, achieving a balance between hardness and toughness. The steel has sufficient hardness to resist wear and good toughness to avoid brittleness;

[0032] 2. By adding Cu and Cr elements, a dense oxide film and corrosion-resistant layer are formed on the surface of the steel, which makes the steel have excellent wet wear resistance and can effectively resist wear and corrosion in a wet environment.

[0033] 3. The addition of Cu and Nb elements enhances the corrosion resistance.

[0034] 4. With the addition of trace element niobium, the grain size of copper-containing wear-resistant steel is significantly refined, and the grain size is the smallest when the niobium content is 0.04%; with the increase of niobium content, the yield strength and tensile strength of copper-containing wear-resistant steel gradually increase, and reach the best when the niobium content is 0.04%;

[0035] 5. The prepared low-alloy wear-resistant steel has good welding performance and high-temperature stability. It can be used for heavy machinery equipment in the wet grinding field, such as wet grinding ball mills, wet grinding mortar mixers, etc. It has long-lasting wear resistance and can greatly improve the service life of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A flow chart of a method for preparing low alloy wear-resistant steel for wet grinding conditions according to a preferred embodiment of the present invention;

[0037] Figure 2 The metallographic structure diagram of the low alloy wear-resistant steel used for wet grinding conditions under a metallographic microscope according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments.

[0039] The following multiple embodiments provide a low-alloy wear-resistant steel for wet grinding conditions, wherein the material composition according to mass percentage is: C is 0.3%-0.35%, Cr is 1.0%-1.3%, Ni≤0.25%, Mo is 0.4%-0.5%, Si is 0.8%-1.2%, Mn is 0.8%-1.2%, Cu is 0.2%-0.3%, Nb≤0.04%, B is 0.003%, S≤0.025%, P≤0.025%, and the remainder is iron and unavoidable impurities.

[0040] Preferably, the mass percentage of Cu is 0.25%.

[0041] Preferably, the mass percentage of Nb is 0.02%.

[0042] Preferably, the mass percentage of Cr is 1.2%.

[0043] A second aspect of the present invention provides a method for preparing low alloy wear-resistant steel for wet grinding conditions, comprising the following steps:

[0044] S1, determining the amount of raw materials for preparing the low alloy wear-resistant steel, wherein the raw materials include scrap steel, pig iron, scrap copper, ferrochrome, ferrosilicon, ferromanganese, ferromolybdenum, nickel block, ferroniobium and a carburizer;

[0045] In this embodiment, S1 includes: calculating the weight of the required scrap steel, pig iron, scrap copper, ferrochrome, ferrosilicon, ferromanganese, ferromolybdenum, nickel block, ferroniobium and carburizer according to the mass percentage of the designed alloy.

[0046] S2, adding the scrap steel and a first mass percentage of a recarburizer into a smelting furnace to melt the scrap steel;

[0047] In this embodiment, the scrap steel and 50% by mass of the recarburizer are added to the smelting furnace to melt the scrap steel; wherein, after adding the scrap steel to the smelting furnace, the scrap steel is first preheated by powering on at a low power, and then the scrap steel is melted by powering on at a high power after the current of the smelting furnace is stabilized;

[0048] S3, after detecting that the melting amount of the scrap steel exceeds a first threshold, adding other raw materials except the scrap steel for comprehensive smelting;

[0049] In this embodiment, when it is detected that the melted amount of the scrap steel exceeds half of the total amount of the scrap steel, pig iron, scrap copper, ferrochrome, ferromanganese, ferrosilicon, ferromolybdenum, nickel block, ferroniobium and another 50% by mass of a carburizer are added in sequence to continue smelting;

[0050] S4, detecting that the comprehensive smelting is finished, adding a proper amount of element B and deoxidizing agent Al to deoxidize the smelting product;

[0051] S5, after deoxidation is completed, the smelted product is controlled to be discharged from the smelting furnace within a certain temperature range, and rapid hot pouring is performed immediately after being discharged from the smelting furnace;

[0052] S6, cooling the casting formed after pouring to below the first temperature for heat treatment to obtain low alloy wear-resistant steel for wet grinding conditions.

[0053] In this embodiment, the furnace temperature range is 1580-1600° C., so that the process parameters of rapid thermal pouring can be reasonably determined.

[0054] In this embodiment, the first temperature is 200° C., so as to better form a huge temperature difference with the heating temperature in the first heating process of the heat treatment, thereby ensuring the performance of the alloy wear-resistant steel.

[0055] As a preferred embodiment, the heat treatment comprises:

[0056] (1) Heating: heating the casting formed after pouring to a heating temperature of 860° C. to 910° C. at a heating rate not exceeding 80° C. / h;

[0057] (2) heat preservation: keeping the casting formed after pouring at the heating temperature for at least 60 minutes to ensure that the alloy elements are uniformly dissolved in the iron matrix of the casting;

[0058] (3) Quenching: immersing the casting formed after the heat preservation into an oil medium and cooling it at a rate of 50° C. / min until it reaches room temperature;

[0059] (4) Tempering: The casting formed after quenching is subjected to tempering treatment to reduce the hardness of the casting and improve its toughness; the casting formed after pouring is heated again to 200°C-230°C at a heating rate not exceeding 80°C / h, maintained at this temperature for 1 hour, and then cooled to room temperature in air.

[0060] Example 1

[0061] A low alloy wear-resistant steel for wet grinding conditions, the chemical composition of which is, by mass percentage, C0.35%, Cr1.3%, Ni0.2%, Mo0.4%, Si0.8%, Mn1.0%, Cu0.3%, Nb0.04%, B0.003%, S<=0.025%, P<=0.025%, and the balance is iron and unavoidable impurities.

[0062] The preparation method is as follows:

[0063] 1. Calculate the weight of scrap steel, pig iron, scrap copper, ferrochrome, ferrosilicon, ferromanganese, ferromolybdenum, nickel block, ferroniobium and carburizer required according to the mass percentage of the designed alloy;

[0064] 2. Add 50% of scrap steel and carburizer into the smelting furnace, use low power to energize, and use high power after the current stabilizes;

[0065] 3. When half of the scrap steel is melted, add scrap copper, ferrochrome, ferromanganese, ferrosilicon, ferromolybdenum, nickel block, ferroniobium and another 50% of the carburizer in turn to continue smelting;

[0066] 4. At the end of smelting, add B and Al for deoxidation;

[0067] 5. Control the temperature of molten steel out of the furnace at 1600℃, and perform rapid hot pouring immediately after it comes out of the furnace;

[0068] 6. The cast casting is cooled to below 200°C, heated to about 910°C at a heating rate not exceeding 80°C / h, maintained at this temperature for 60 minutes, immersed in an oil medium and cooled at a rate of 50°C / min to room temperature; then heated to 230°C at a heating rate of 80°C / h, maintained at this temperature for 60 minutes, taken out of the furnace and cooled to room temperature in the air to obtain low-alloy wear-resistant steel for wet grinding conditions.

[0069] Example 2

[0070] A new type of low-alloy wear-resistant steel for wet grinding conditions, the chemical composition of which is, by mass percentage, C0.3%, Cr1.3%, Ni0.2%, Mo0.4%, Si0.8%, Mn1.0%, Cu0.3%, Nb0.01%, B0.001%, S<=0.025%, P<=0.025%, and the balance is iron and inevitable impurities.

[0071] The preparation method is as follows:

[0072] 1. Calculate the weight of scrap steel, pig iron, scrap copper, ferrochrome, ferrosilicon, ferromanganese, ferromolybdenum, nickel block, ferroniobium and carburizer required according to the mass percentage of the designed alloy;

[0073] 2. Add 50% of scrap steel and carburizer into the smelting furnace, use low power to energize, and use high power after the current stabilizes;

[0074] 3. When half of the scrap steel is melted, add scrap copper, ferrochrome, ferromanganese, ferrosilicon, ferromolybdenum, nickel block, ferroniobium and another 50% of the carburizer in turn to continue smelting;

[0075] 4. At the end of smelting, add B and Al for deoxidation;

[0076] 5. Control the temperature of molten steel out of the furnace at 1580℃, and perform rapid hot pouring immediately after it comes out of the furnace;

[0077] 6. The cast casting is cooled to below 200°C, heated to about 860°C at a heating rate not exceeding 80°C / h, maintained at this temperature for 60 minutes, immersed in an oil medium and cooled at a rate of 50°C / min to room temperature; then heated to 200°C at a heating rate of 80°C / h, maintained at this temperature for 60 minutes, taken out of the furnace and cooled to room temperature in the air to obtain low-alloy wear-resistant steel for wet grinding conditions.

[0078] Example 3

[0079] A new type of low-alloy wear-resistant steel for wet grinding conditions, the chemical composition of which is, by mass percentage, C0.32%, Cr1.0%, Ni0.2%, Mo0.4%, Si0.8%, Mn1.0%, Cu0.1%, Nb0.04%, B0.003%, S<=0.025%, P<=0.025%, and the balance is iron and inevitable impurities.

[0080] The preparation method is as follows:

[0081] 1. Calculate the weight of scrap steel, pig iron, scrap copper, ferrochrome, ferrosilicon, ferromanganese, ferromolybdenum, nickel block, ferroniobium and carburizer required according to the mass percentage of the designed alloy;

[0082] 2. Add 50% of scrap steel and carburizer into the smelting furnace, use low power to energize, and use high power after the current stabilizes;

[0083] 3. When half of the scrap steel is melted, add scrap copper, ferrochrome, ferromanganese, ferrosilicon, ferromolybdenum, nickel block, ferroniobium and another 50% of the carburizer in turn to continue smelting;

[0084] 4. At the end of smelting, add B and Al for deoxidation;

[0085] 5. The furnace temperature of the molten steel is controlled at 1590°C. After being poured out of the furnace, rapid hot pouring is performed immediately. The temperature of the cast casting is cooled to below 200°C, and then heated to a temperature of about 895°C at a heating rate not exceeding 80°C / h. After maintaining the temperature for 60 minutes, the molten steel is immersed in an oil medium and cooled at a rate of 50°C / min to room temperature. Then, the molten steel is heated to 215°C at a heating rate of 80°C / h, and the temperature is maintained for 60 minutes. After that, the molten steel is taken out of the furnace and cooled to room temperature in the air to obtain a low alloy wear-resistant steel for wet grinding conditions.

[0086] Comparative Example 1

[0087] A low alloy wear-resistant steel, the chemical composition of which is, by mass percentage, C0.35%, Cr1.3%, Ni0.2%, Mo0.4%, Si0.8%, Mn1.0%, S<=0.025%, P<=0.025%, and the balance is iron and inevitable impurities. Compared with Example 1, Comparative Example 1 does not contain Cu, Nb and B, and B is not added for deoxidation in the preparation method, and the rest is consistent with Example 1.

[0088] Comparative Example 2

[0089] A low alloy wear-resistant steel, the chemical composition of which is, by mass percentage, C0.25%, Cr1.3%, Ni0.2%, Mo0.4%, Si0.8%, Mn1.0%, Cu0.3%, Nb0.04%, B0.003%, S<=0.025%, P<=0.025%, and the balance is iron and inevitable impurities. Compared with Example 1, the C content in Comparative Example 2 is lower, and the preparation method is consistent with that of Example 1.

[0090] Comparative Example 3

[0091] A low alloy wear-resistant steel, the chemical composition of which is, by mass percentage, C0.25%, Cr1.0%, Ni0.2%, Mo0.4%, Si0.8%, Mn1.0%, Cu0.6%, Nb0.08%, B0.003%, S<=0.025%, P<=0.025%, and the balance is iron and inevitable impurities. Compared with Example 1, the C content in Comparative Example 3 is lower, and the Cu and Nb contents are higher, and the preparation method is consistent with that in Example 1.

[0092] Performance Testing

[0093] The tensile test was carried out in accordance with GB / T228-2010 tensile test for metal materials; the hardness test was carried out in accordance with GB / T230.1-2018 Rockwell hardness test for metals; the impact toughness was carried out in accordance with GB / T 229-2007 Charpy pendulum impact test method for metal materials, and the specimen was a V-notched specimen; the measurement of martensite and residual austenite in steel was carried out in accordance with YB / T 5338-2019 X-ray diffractometer method for quantitative determination of austenite in steel and scanning electron microscope backscattered electron diffraction technology. Static corrosion resistance experiments were carried out, and 168h corrosion tests were carried out in solutions of different properties to calculate the uniform corrosion rate.

[0094] The test results are shown in Table 1 and Table 2.

[0095] Table 1 Hardness and other test results

[0096]

[0097]

[0098] It can be seen from Table 1 that the hardness and toughness of Examples 1-3 are better than those of Comparative Examples 1-3.

[0099] Table 2 Corrosion rate test results (gm -2 h -1 )

[0100] project pH=3.5 pH=7.0 pH=11 Example 1 0.32 0.10 0.25 Example 2 0.39 0.15 0.30 Example 3 0.36 0.13 0.29 Comparative Example 1 0.58 0.31 0.49 Comparative Example 2 0.45 0.22 0.37 Comparative Example 3 0.35 0.21 0.33

[0101] It can be seen from Table 2 that the corrosion resistance of Examples 1-3 in acidic, neutral and alkaline environments is better than that of Comparative Examples 1-3.

[0102] like Figure 2 The metallographic structure diagram of the wear-resistant steel obtained after heat treatment of the casting for wet grinding conditions is shown in FIG. Figure 2 As shown, the final structure obtained after quenching and tempering is a mixture of martensite, bainite and a small amount of carbide particles; the martensite is lath martensite and needle martensite, and the volume fraction of martensite is ≥91.7%, which can better resist the expansion of cracks caused by wear and impact, hinder deformation and fatigue wear, and thus improve wear resistance.

[0103] The above descriptions are merely embodiments of the present invention. It should be pointed out that, for those skilled in the art, various changes, modifications, substitutions and variations can be made to these embodiments without departing from the technical principles of the present invention. These changes, modifications, substitutions and variations should also be regarded as the scope of protection of the present invention.

Claims

1. A low alloy wear-resistant steel for wet grinding conditions, characterized in that: The material composition in mass percentage is: C 0.3%-0.35%, Cr 1.0%-1.3%, Ni≤0.25%, Mo 0.4%-0.5%, Si 0.8%-1.2%, Mn 0.8%-1.2%, Cu 0.2%-0.3%, Nb≤0.04%, B 0.003%, S≤0.025%, P≤0.025%, and the balance is iron and unavoidable impurities.

2. The low alloy wear-resistant steel for wet grinding according to claim 1, characterized in that: The mass percentage of Cu is 0.25%.

3. The low alloy wear-resistant steel for wet grinding according to claim 1, characterized in that: The mass percentage of Nb is 0.02%.

4. The low alloy wear-resistant steel for wet grinding according to claim 1, characterized in that: The mass percentage of Cr is 1.2%.

5. A method for preparing low alloy wear-resistant steel for wet grinding conditions, used for preparing the low alloy wear-resistant steel according to any one of claims 1 to 4, characterized in that: The steps include: S1, determining the amount of raw materials for preparing the low alloy wear-resistant steel, wherein the raw materials include scrap steel, pig iron, scrap copper, ferrochrome, ferrosilicon, ferromanganese, ferromolybdenum, nickel block, ferroniobium and a carburizer; S2, adding the scrap steel and a first mass percentage of a recarburizer into a smelting furnace to melt the scrap steel; S3, after detecting that the melting amount of the scrap steel exceeds a first threshold, adding other raw materials except the scrap steel for comprehensive smelting; S4, detecting that the comprehensive smelting is finished, adding a proper amount of element B and deoxidizing agent Al to deoxidize the smelting product; S5, after deoxidation is completed, the smelted product is controlled to be discharged from the smelting furnace within a certain temperature range, and rapid hot pouring is performed immediately after being discharged from the smelting furnace; S6, cooling the casting formed after pouring to below the first temperature for heat treatment to obtain low alloy wear-resistant steel for wet grinding conditions.

6. The method for preparing low alloy wear-resistant steel for wet grinding conditions according to claim 5, characterized in that: The S2 comprises: adding the scrap steel and 50% by mass of a recarburizer into a smelting furnace to melt the scrap steel; wherein, after adding into the smelting furnace, firstly preheating with low power, and then melting the scrap steel with high power after the current of the smelting furnace is stabilized.

7. The method for preparing low alloy wear-resistant steel for wet grinding conditions according to claim 6, characterized in that: The S3 comprises: when it is detected that the melted amount of the scrap steel exceeds half of the total amount of the scrap steel, pig iron, scrap copper, ferrochrome, ferromanganese, ferrosilicon, ferromolybdenum, nickel block, ferroniobium and another 50% by mass percentage of carburizer are added in sequence to continue smelting.

8. The method for preparing low alloy wear-resistant steel for wet grinding conditions according to claim 7, characterized in that: The furnace temperature range is 1580-1600°C.

9. The method for preparing low alloy wear-resistant steel for wet grinding conditions according to claim 8, characterized in that: The first temperature is 200°C.

10. The method for preparing low alloy wear-resistant steel for wet grinding conditions according to claim 9, characterized in that: The heat treatment comprises: (1) Heating: heating the casting formed after pouring to a heating temperature of 860° C. to 910° C. at a heating rate not exceeding 80° C. / h; (2) heat preservation: keeping the casting formed after pouring at the heating temperature for at least 60 minutes to ensure that the alloy elements are uniformly dissolved in the iron matrix of the casting; (3) Quenching: immersing the casting formed after the heat preservation into an oil medium and cooling it at a rate of 50° C. / min until it reaches room temperature; (4) Tempering: The casting formed after quenching is subjected to tempering treatment to reduce the hardness of the casting and improve its toughness; the casting formed after pouring is heated again to 200°C-230°C at a heating rate not exceeding 80°C / h, maintained at this temperature for 1 hour, and then cooled to room temperature in air.

Images