Production process of as-cast wear-resistant steel ball using multi-element modified alloy

Abstract

The invention relates to the technical field of wear-resistant steel ball casting, and discloses a process for producing as-cast wear-resistant steel balls by using a multi-element modified alloy, which comprises the following steps of: smelting molten steel, namely putting raw materials into an electric arc furnace or an induction furnace, heating to 1550-1650 DEG C, and smelting to obtain basic molten steel; multi-element modified alloy is added, specifically, the multi-element modified alloy is added into the smelted molten steel, the adding amount of the multi-element modified alloy accounts for 0.5%-2.0% of the total weight of the molten steel, stirring is conducted for 10-30 minutes at the temperature of 1500-1600 DEG C, and the alloy is made to be evenly dispersed; performing modification treatment; according to the multi-element modified alloy, through the synergistic effect of the rare earth element RE and the alkaline metal components Ba and Ca, deep deoxidation and impurity purification are achieved in the molten steel smelting stage, the oxygen activity is reduced, non-metallic inclusion residues are reduced, meanwhile, the grain structure is refined through a solid solution strengthening mechanism of MnN and CrN, a uniform and compact matrix structure is formed, and therefore the corrosion resistance of the alloy is improved. And the overall compactness and impact toughness of the wear-resistant steel ball are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wear-resistant steel ball casting, in particular to a production process of as-cast wear-resistant steel ball using multi-element modification alloy. BACKGROUND

[0002] Wear-resistant steel ball, also known as grinding steel ball, is a consumable used for crushing materials in a ball mill, mainly applied to grinding operations in mining, cement, metallurgy, power and chemical industries, and is used to bear high strength wear in high-speed running equipment to prolong the service life of the equipment. It is a crushing medium used in a ball mill. Wear-resistant steel ball is obtained by casting or hot rolling or forging and then heat treatment of chromium alloy cast iron, ductile cast iron, round steel and other materials. According to the different raw materials used, the wear-resistant steel ball has different surface hardness and core hardness, and is used for grinding various materials.

[0003] At present, due to the multiple process coupling in the production process of multi-element modification alloy as-cast wear-resistant steel ball, when the steel liquid is deeply purified, the vacuum / inert gas protection system provided acts on the surface of the steel liquid, and the reaction uniformity in the modification alloy dissolution process cannot be monitored in real time. When local area appears alloy dispersion uneven and not fully activated, it will cause the fluctuation of deoxidation and grain refinement effect, and it is difficult to ensure the stability of steel liquid purification.

[0004] Therefore, the present application provides a production process of as-cast wear-resistant steel ball using multi-element modification alloy to solve the above problems. SUMMARY

[0005] (I) Technical problems solved

[0006] In view of the deficiencies of the prior art, the present application provides a production process of as-cast wear-resistant steel ball using multi-element modification alloy, which solves the problems raised in the background art.

[0007] (II) Technical solutions

[0008] In order to achieve the above purpose, the present application provides the following technical solutions: a production process of as-cast wear-resistant steel ball using multi-element modification alloy, comprising the following steps:

[0009] Step 1: Steel smelting, placing the raw materials in an electric arc furnace or an induction furnace, heating to 1550-1650°C for smelting, and obtaining a base steel liquid;

[0010] Step two: adding multi-component modification alloy, adding multi-component modification alloy to the molten steel after smelting, the amount is 0.5-2.0% of the total weight of the molten steel, and stirring for 10-30 minutes at 1500-1600°C, so that the alloy is uniformly dispersed, the multi-component modification alloy contains RE, Ba, Ca, MnN, CrN and Mo components, replaces part of deoxidizing aluminum, strengthens deoxidation by alkaline metal elements, improves fluidity, and realizes grain refinement and solid solution strengthening, wherein RE is a rare earth element selected from at least one of lanthanide series metals;

[0011] Step three: modification treatment, in a vacuum or inert gas protection environment, the pressure is controlled to be 1× -1× Pa, the treatment time is 5-15 minutes, and deep deoxidization and molten steel purification are carried out;

[0012] Step four: casting forming, pouring the treated molten steel into a metal mold preheated to 800-1000°C, the pouring temperature is 1420-1500°C, and the pouring speed is 10-30 cm / s, to form a wear-resistant steel ball casting;

[0013] Step five: solid solution treatment and cooling, immediately after casting, air cooling or water quenching cooling to room temperature, and then tempering at 200-300°C for 1-2 hours, to obtain a wear-resistant steel ball with uniform as-cast structure and no internal pores;

[0014] The process reduces the oxygen activity of the wear-resistant steel ball to ≤10 PPM, the P content to ≤0.015%, the S content to ≤0.020%, the volume hardness HRC to ≥55, the unit wear to ≤100 grams / ton, and the out-of-roundness rate to ≤5%.

[0015] Preferably, the weight percentage composition of the multi-component modification alloy is: RE: 5-20%, Ba: 5-25%, Ca: 5-15%, MnN: 1-10%, CrN: 5-10%, Mo: 3-10%;

[0016] The amount of rare earth elements added is 1% of the total alloy weight, and the balance is iron and unavoidable impurities;

[0017] The alloy preparation includes: sorting and cleaning the waste ceramic fibers, drying, crushing and grinding to a particle size of 80-100 μm, injecting nitrogen gas at 10-50 sccm in a vacuum reaction chamber, plasma treatment power of 300-700 W, time of 7-15 minutes, to obtain active surface enhanced ceramic particles, and mixing with metal powder to smelt into an alloy.

[0018] Preferably, the raw material composition for smelting the molten steel in step one is:

[0019] C: 2.0-3.0%, Si: 0.3-0.5%, Mn: 0.4-0.5%, Cr: 0.5-0.6%, Ni: 0.1-0.2%, Ti: 0.01-0.02%, B: 0.001-0.002%, balance iron;

[0020] The melting process includes: after adding raw materials in the melting furnace, heating to the target temperature at 10-15 °C / min, holding for 20-40 minutes, using an electromagnetic stirrer to stir at a speed of 50-100 r / min to ensure uniform composition.

[0021] Preferably, the specific parameters of the multi-element modification alloy added in step two are:

[0022] The addition temperature is controlled at 1520-1580 °C, the stirring speed is 100-150 r / min, and the stirring time is 15-25 minutes;

[0023] The stirring device is a variable frequency mechanical stirrer with a power of 5-10 kW to ensure that the alloy is fully dissolved and reacts with the steel liquid;

[0024] When the addition amount is 1.0%, the steel flowability improvement rate reaches 30%, and the mold filling capacity is improved;

[0025] The multi-element modification alloy is added in the form of particles with a particle size of ≤100 μm and is uniformly sprayed into the molten pool through a pneumatic conveying system.

[0026] Preferably, the vacuum environment of the modification treatment in step three is:

[0027] The vacuum degree is set to 1× Pa, the nitrogen injection rate is 30 sccm, and the treatment time is 10 minutes;

[0028] Or the inert gas protection uses argon with a flow rate of 20-40 L / min to cover the surface of the steel liquid;

[0029] The modification treatment process includes: using a spectrometer to monitor the oxygen activity of the steel liquid online, and terminating the treatment when the oxygen activity decreases from the initial 20-30 PPM to ≤10 PPM;

[0030] The purification effect reduces non-metallic inclusions by ≥40%, reduces P content from 0.025% to ≤0.015%, and reduces S content from 0.030% to ≤0.020%.

[0031] Preferably, the mold parameters of the casting forming in step four are:

[0032] The mold preheating temperature is 900 °C, and the surface is coated with a boron nitride coating to reduce mold sticking;

[0033] Casting temperature 1440°C-1460°C, casting speed 20cm / s, mold filling time ≤60 seconds;

[0034] The casting process comprises: using an inclined casting system, designing the gate as a cone, and ensuring the molten steel to fill the mold smoothly under a casting pressure of 0.2-0.5MPa.

[0035] The diameter of the formed wear-resistant steel ball ranges from 50mm to 150mm, the surface roughness Ra is ≤3.2μm, and there is no shrinkage or cold shut defect.

[0036] Preferably, the specific operation of the solid solution treatment and cooling in step five comprises:

[0037] The air cooling adopts a forced air cooling system, the wind speed is 5-10m / s, the cooling rate is 50-100°C / min, and the temperature is lowered to 200°C;

[0038] Or the water quenching adopts room temperature water, the quenching time is 10-30 seconds, and the cooling rate is ≥200°C / min.

[0039] The tempering treatment after the solid solution treatment and cooling is carried out at 250°C for 1.5 hours, and the furnace atmosphere is nitrogen protection.

[0040] The wear-resistant steel ball after the solid solution treatment and cooling has no internal cracks.

[0041] The solid solution strengthening makes the matrix hardness increase by 5-10 units of HRC.

[0042] Preferably, the multi-element modification alloy needs to be dried and pretreated before being added, and the specific operation comprises: placing the alloy powder in a drying device and treating it at a temperature of 200-300°C for 1-2 hours to remove the adsorbed moisture.

[0043] Preferably, the process further comprises a post-processing step:

[0044] The wear-resistant steel ball after cooling is subjected to shot peening treatment, the shot peening pressure is 0.4-0.6MPa, the steel shot diameter is 0.5-1.0mm, and the time is 5-10 minutes.

[0045] Then, the hardness, size and roundness are detected, and the qualified products are coated with rust-proof oil.

[0046] The shot peening treatment increases the surface compressive stress by 200-300MPa and improves the fatigue life by 20%.

[0047] The detection standard is: hardness HRC≥55, core and surface deviation ≤2HRC, diameter tolerance ±0.5mm, and out-of-roundness ≤3%.

[0048] Preferably, the performance indicators of the wear-resistant steel ball include:

[0049] Volume hardness HRC 58-62, unit wear 70-90g / t, out-of-roundness rate ≤3%, still maintaining roundness when ground to diameter ≤10mm;

[0050] Metallographic structure shows uniform distribution of carbides, without continuous network structure;

[0051] The performance is verified by comparison test: the post-use oxygen activity is reduced from 25PPM to 8PPM, the casting time is shortened by 30%, the P content is 0.010%, the S content is 0.016%, and the impact toughness is ≥15J / cm².

[0052] (Three) beneficial effects

[0053] Compared with the prior art, the present application provides a production process of as-cast wear-resistant steel ball using multi-element modification alloy, which has the following beneficial effects:

[0054] 1. In the present application, the multi-element modification alloy realizes deep deoxidation and impurity purification in the steel liquid smelting stage through the synergistic effect of rare earth elements RE and alkaline metal components Ba and Ca, reduces oxygen activity and reduces non-metallic inclusion residues, at the same time, the solid solution strengthening mechanism of MnN and CrN refines the grain structure, forms a uniform and dense matrix structure, suppresses pores and segregation defects, and improves the overall density and impact toughness of the wear-resistant steel ball.

[0055] 2. In the present application, the modification treatment is carried out in a vacuum or inert gas protection environment, by controlling the matching of pressure and gas atmosphere, the active components of the multi-element modification alloy are fully dispersed and the surface reaction is activated, the flowability of the steel liquid is optimized and the filling capacity is strengthened, the turbulent flow interference and abnormal temperature gradient in the casting process are avoided, the solidification front is ensured to expand stably, the forming defects such as shrinkage and cold shut are simultaneously eliminated, and the homogenization and high integrity of the as-cast structure are realized.

[0056] 3. In the present application, the synergistic regulation of solid solution treatment and cooling stage combined with the removal of adsorbed moisture of alloy powder by dry pretreatment ensures the cold speed adaptability of high temperature phase change process, matches the size characteristics of steel balls of different diameters through air cooling or water quenching strategy, suppresses the generation of micro-cracks and the risk of carbide coarsening, at the same time, the surface compressive stress distribution is enhanced after shot peening post-treatment, which synergistically improves the hardness consistency of the core and the surface layer and the fatigue life stability, optimizes the wear resistance and shape retention ability of the product. BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1 It is a flow chart of the production process of as-cast wear-resistant steel ball using multi-element modification alloy of the present application. DETAILED DESCRIPTION

[0058] With reference to the accompanying drawings: the technical solutions in the embodiments of the present application will be apparently and completely described, obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by one of ordinary skill in the art without creative labor belong to the scope of protection of the present application.

[0059] Embodiment one, a production process of as-cast wear-resistant steel ball using multi-element modification alloy, comprising the following steps:

[0060] Step one: smelting of molten steel, placing raw materials in an electric arc furnace or an induction furnace, heating to 1550°C for smelting, and obtaining a base molten steel;

[0061] Step two: multi-element modification alloy addition, adding multi-element modification alloy to the smelted molten steel, the addition amount being 0.5% of the total weight of the molten steel, and stirring for 10 minutes at 1500°C to make the alloy uniformly dispersed, the multi-element modification alloy comprising RE, Ba, Ca, MnN, CrN and Mo components, replacing part of deoxidizing aluminum, strengthening deoxidization and improving fluidity through alkaline metal elements, and realizing grain refinement and solid solution strengthening, wherein RE is a rare earth element selected from at least one of lanthanide series metals;

[0062] Step three: modification treatment, under vacuum or inert gas protection environment, controlling the pressure to be 1x Pa, and the treatment time being 5 minutes, for deep deoxidization and molten steel purification;

[0063] Step four: casting forming, pouring the treated molten steel into a metal mold preheated to 800°C, the casting temperature being 1420°C, and the casting speed being 10 cm / s, to form a wear-resistant steel ball casting;

[0064] Step five: solid solution treatment and cooling, immediately performing air cooling or water quenching cooling to room temperature after casting, and then tempering at 200°C for 1 hour, to obtain a wear-resistant steel ball with uniform as-cast structure and no internal pores;

[0065] The process reduces the oxygen activity of the wear-resistant steel ball to ≤10 PPM, the P content to ≤0.015%, the S content to ≤0.020%, the volume hardness HRC to ≥55, the unit abrasion to ≤100 grams / ton, and the out-of-roundness rate to ≤5%.

[0066] The weight percentage composition of the multi-element modification alloy is: RE: 5%, Ba: 5%, Ca: 5%, MnN: 1%, CrN: 5%, and Mo: 3%;

[0067] The rare earth element addition amount is 1% of the total alloy weight, and the balance is iron and unavoidable impurities;

[0068] The alloy preparation comprises: sorting, cleaning and drying the waste ceramic fiber, crushing and grinding to a particle size of 80 μm, injecting nitrogen of 10 sccm in a vacuum reaction chamber, plasma treatment power of 300 W, time of 7 minutes, and obtaining active surface enhanced ceramic particles, and mixing and smelting into an alloy with metal powder.

[0069] The raw material composition of the molten steel in step one is:

[0070] C: 2.0%, Si: 0.3%, Mn: 0.4%, Cr: 0.5%, Ni: 0.1%, Ti: 0.01%, B: 0.001%, and the balance is iron;

[0071] The smelting process comprises: after adding the raw material in the smelting furnace, heating to the target temperature at 10 °C / min, holding for 20 minutes, and stirring at a speed of 50 r / min by using an electromagnetic stirrer to ensure uniform composition.

[0072] The specific parameters of the multi-component modification alloy added in step two are:

[0073] The addition temperature is controlled at 1520 °C, the stirring speed is 100 r / min, and the stirring time is 15 minutes;

[0074] The stirring device is a variable frequency mechanical stirrer with a power of 5 kW, which ensures that the alloy is fully dissolved and reacts with the molten steel;

[0075] When the addition amount is 1.0%, the molten steel fluidity improvement rate reaches 30%, and the mold filling capacity is improved;

[0076] The multi-component modification alloy is added in the form of particles with a particle size of ≤100 μm, and is uniformly sprayed into the molten pool through a pneumatic conveying system.

[0077] The specific vacuum environment of the modification treatment in step three is:

[0078] The vacuum degree is set to 1× Pa, the nitrogen injection rate is 30 sccm, and the treatment time is 10 minutes;

[0079] Or the inert gas protection adopts argon with a flow rate of 20 L / min to cover the surface of the molten steel;

[0080] The modification treatment process comprises: online monitoring of the oxygen activity of the molten steel by using a spectrometer, and terminating the treatment when the oxygen activity decreases from the initial 20 PPM to ≤10 PPM;

[0081] The purification effect reduces the non-metallic inclusions by ≥40%, the P content decreases from 0.025% to ≤0.015%, and the S content decreases from 0.030% to ≤0.020%.

[0082] The mold parameters of the casting forming in step four are:

[0083] Mold preheating temperature 900°C, surface coated with boron nitride coating to reduce sticking;

[0084] Pouring temperature 1440°C, pouring speed 20 cm / s, mold filling time ≤ 60 seconds;

[0085] The casting forming process includes: using an inclined casting system, the gate is designed as a cone, the casting pressure is 0.2 MPa, and the molten steel is ensured to fill the mold smoothly;

[0086] After forming, the diameter of the wear-resistant steel ball ranges from 50 mm, the surface roughness Ra is ≤ 3.2 μm, and there are no shrinkage or cold shut defects.

[0087] The specific operation of solid solution treatment and cooling in step five includes:

[0088] Air cooling uses a forced air cooling system, the wind speed is 5 m / s, the cooling rate is 50°C / min, and the temperature is cooled to 200°C;

[0089] Or water quenching uses room temperature water, quenching time is 10 seconds, cooling rate ≥ 200°C / min;

[0090] The tempering treatment after solid solution treatment and cooling is carried out at 250°C for 1.5 hours, and the furnace atmosphere is nitrogen protection;

[0091] The wear-resistant steel ball after solid solution treatment and cooling has no internal cracks;

[0092] Solid solution strengthening makes the matrix hardness increase by HRC 5 units.

[0093] The multi-element modification alloy needs to be dried before being added, and the specific operation includes: placing the alloy powder in a drying device and treating it at 200°C for 1 hour to remove adsorbed water.

[0094] The process also includes a post-processing step:

[0095] The wear-resistant steel ball after cooling is subjected to shot peening treatment, the shot peening pressure is 0.4 MPa, the steel shot diameter is 0.5 mm, and the time is 5 minutes;

[0096] Then detect hardness, size and roundness, and the qualified products are coated with rust-proof oil;

[0097] Shot peening increases the surface compressive stress by 200 MPa and increases the fatigue life by 20%;

[0098] Among them, the detection standard is: hardness HRC ≥ 55, core and surface deviation ≤ 2HRC, diameter tolerance ± 0.5 mm, and out-of-roundness ≤ 3%.

[0099] The performance indicators of the wear-resistant steel ball include:

[0100] Volume hardness HRC 58, unit wear 70g / t, out-of-roundness ≤3%, still keep round when grinding to diameter ≤10mm;

[0101] Metallographic structure shows that carbide is uniformly distributed without continuous network structure;

[0102] Performance is verified by comparison test: oxygen activity is reduced from 25PPM to 8PPM after use, casting time is shortened by 30%, P content is 0.010%, S content is 0.016%, impact toughness ≥15J / cm².

[0103] Embodiment two, a production process of as-cast wear-resistant steel ball using multi-element modification alloy, comprising the following steps:

[0104] Step one: smelting of molten steel, placing raw materials in electric arc furnace or induction furnace, heating to 1600°C for smelting, obtaining base molten steel;

[0105] Step two: adding multi-element modification alloy, adding multi-element modification alloy to the smelted molten steel, the adding amount is 1.5% of the total weight of the molten steel, and stirring for 20 minutes at 1550°C to make the alloy uniformly dispersed, the multi-element modification alloy contains RE, Ba, Ca, MnN, CrN and Mo components, replacing part of deoxidizing aluminum, strengthening deoxidization and improving fluidity through alkaline metal elements, and realizing grain refinement and solid solution strengthening, wherein RE is a rare earth element selected from at least one of lanthanide series metals;

[0106] Step three: modification treatment, under vacuum or inert gas protection environment, controlling pressure to 1× Pa, treatment time 10 minutes, for deep deoxidization and molten steel purification;

[0107] Step four: casting forming, pouring the treated molten steel into a metal mold preheated to 900°C, the casting temperature is 1460°C, the casting speed is 20cm / s, forming wear-resistant steel ball castings;

[0108] Step five: solid solution treatment and cooling, immediately after casting, air cooling or water quenching cooling to room temperature, then tempering at 250°C for 1.5 hours, obtaining wear-resistant steel ball with uniform as-cast structure and no internal pores;

[0109] The process reduces oxygen activity of wear-resistant steel ball to ≤10PPM, P content to ≤0.015%, S content to ≤0.020%, volume hardness HRC to ≥55, unit wear to ≤100g / t, and out-of-roundness to ≤5%.

[0110] The weight percentage composition of the multi-element modification alloy is: RE: 15%, Ba: 18%, Ca: 12%, MnN: 5%, CrN: 8%, Mo: 7%;

[0111] The rare earth element is added in an amount of 1% of the total alloy weight, and the remainder is iron and unavoidable impurities;

[0112] The alloy preparation includes: sorting, cleaning, drying, crushing and grinding the waste ceramic fiber to a particle size of 90 μm, injecting nitrogen at 30 sccm in a vacuum reaction chamber, plasma treatment power of 500 W, time of 12 minutes, and obtaining an active surface enhanced ceramic particle, and mixing with metal powder to smelt into an alloy.

[0113] The raw material composition of the molten steel in step one is:

[0114] C: 2.5%, Si: 0.4%, Mn: 0.45%, Cr: 0.55%, Ni: 0.15%, Ti: 0.01%, B: 0.001%, and the remainder is iron;

[0115] The smelting process includes: after adding the raw materials in the smelting furnace, heating to the target temperature at a rate of 12°C / min, holding for 30 minutes, and stirring at a speed of 80 r / min using an electromagnetic stirrer to ensure uniform composition.

[0116] The specific parameters of the multi-element modification alloy added in step two are:

[0117] The addition temperature is controlled at 1550°C, the stirring speed is 120 r / min, and the stirring time is 20 minutes;

[0118] The stirring equipment is a variable frequency mechanical stirrer with a power of 8 kW, which ensures that the alloy is fully dissolved and reacts with the molten steel;

[0119] When the addition amount is 1.0%, the molten steel fluidity improvement rate reaches 30%, and the mold filling capacity is improved;

[0120] The multi-element modification alloy is added in the form of particles with a particle size of ≤100 μm and is uniformly sprayed into the molten pool through a pneumatic conveying system.

[0121] The specific vacuum environment for modification treatment in step three is:

[0122] The vacuum degree is set to 1× Pa, the nitrogen injection rate is 30 sccm, and the treatment time is 10 minutes;

[0123] Or the inert gas protection uses argon with a flow rate of 30 L / min to cover the surface of the molten steel;

[0124] The modification treatment process includes: using a spectrometer to monitor the oxygen activity of the molten steel online, and terminating the treatment when the oxygen activity decreases from the initial 25 PPM to ≤10 PPM;

[0125] The purification effect reduces non-metallic inclusions by ≥40%, the P content decreases from 0.025% to ≤0.015%, and the S content decreases from 0.030% to ≤0.020%.

[0126] The mold parameters in the fourth step of casting forming are as follows:

[0127] The mold preheating temperature is 900°C, and a boron nitride coating is coated on the surface to reduce mold sticking;

[0128] The casting temperature is 1450°C, the casting speed is 20 cm / s, and the mold filling time is ≤60 seconds;

[0129] The casting forming process includes: using an inclined casting system, designing the sprue as a cone, and ensuring the smooth filling of the liquid steel under a casting pressure of 0.4 MPa;

[0130] After forming, the diameter of the wear-resistant steel ball ranges from 100 mm, the surface roughness Ra is ≤3.2 μm, and there are no shrinkage or cold shut defects.

[0131] The specific operations of the solution treatment and cooling in the fifth step include:

[0132] The air cooling uses a forced air cooling system, the wind speed is 8 m / s, the cooling rate is 70°C / min, and the temperature is lowered to 200°C;

[0133] Or the water quenching uses room temperature water, the quenching time is 20 seconds, and the cooling rate is ≥200°C / min;

[0134] The tempering treatment after the solution treatment and cooling is carried out at 250°C for 1.5 hours, and the furnace atmosphere is nitrogen protection;

[0135] The wear-resistant steel ball after the solution treatment and cooling has no internal cracks;

[0136] The solution strengthening makes the matrix hardness increase by 8 units of HRC.

[0137] The multi-element modification alloy needs to be dried and pretreated before being added, and the specific operations include: placing the alloy powder in a drying device and treating it at a temperature of 250°C for 1.5 hours to remove adsorbed moisture.

[0138] The process also includes a post-processing step:

[0139] The wear-resistant steel ball after cooling is subjected to shot peening treatment, the shot peening pressure is 0.5 MPa, the steel shot diameter is 0.8 mm, and the time is 8 minutes;

[0140] Then the hardness, size and roundness are detected, and the qualified products are coated with rust-proof oil;

[0141] The shot peening treatment increases the surface compressive stress by 250 MPa and improves the fatigue life by 20%;

[0142] Among them, the detection standards are: hardness HRC≥55, core and surface deviation ≤2HRC, diameter tolerance ±0.5 mm, and out-of-roundness ≤3%.

[0143] Performance indicators of the wear-resistant steel ball include:

[0144] Volume hardness HRC 60, unit wear 80 grams / ton, out-of-roundness rate ≤3%, still maintaining the roundness when ground to a diameter of ≤10mm;

[0145] The metallographic structure shows that the carbides are uniformly distributed without continuous network structure;

[0146] The performance is verified by comparison test: the oxygen activity is reduced from 25PPM to 8PPM after use, the casting time is shortened by 30%, the P content is 0.010%, the S content is 0.016%, and the impact toughness is ≥15J / cm².

[0147] Example Three, a production process of as-cast wear-resistant steel ball using multi-element modification alloy, comprising the following steps:

[0148] Step One: Steel smelting, placing raw materials in an electric arc furnace or an induction furnace, heating to 1650°C for smelting, and obtaining a base steel liquid;

[0149] Step Two: Multi-element modification alloy addition, adding multi-element modification alloy to the smelted steel liquid, the addition amount being 2.0% of the total weight of the steel liquid, and stirring at 1600°C for 30 minutes to make the alloy uniformly dispersed, the multi-element modification alloy containing RE, Ba, Ca, MnN, CrN and Mo components, replacing part of deoxidizing aluminum, strengthening deoxidization and improving fluidity through alkaline metal elements, and realizing grain refinement and solid solution strengthening, wherein RE is a rare earth element selected from at least one of lanthanide series metals;

[0150] Step Three: Modification treatment, under vacuum or inert gas protection environment, controlling the pressure to be 1× Pa, and the treatment time being 15 minutes, for deep deoxidization and steel liquid purification;

[0151] Step Four: Casting forming, pouring the treated steel liquid into a metal mold preheated to 1000°C, the casting temperature being 1500°C, and the casting speed being 30cm / s, to form a wear-resistant steel ball casting;

[0152] Step Five: Solid solution treatment and cooling, immediately performing air cooling or water quenching cooling to room temperature after casting, and then tempering at 300°C for 2 hours, to obtain a wear-resistant steel ball with uniform as-cast structure and no internal pores;

[0153] The process reduces the oxygen activity of the wear-resistant steel ball to ≤10PPM, the P content to ≤0.015%, the S content to ≤0.020%, the volume hardness HRC to ≥55, the unit wear to ≤100 grams / ton, and the out-of-roundness rate to ≤5%.

[0154] The weight percentage composition of the multi-component modified alloy is: RE: 20%, Ba: 25%, Ca: 15%, MnN: 10%, CrN: 10%, Mo: 10%;

[0155] The rare earth element addition amount is 1% of the total alloy weight, and the balance is iron and unavoidable impurities;

[0156] The alloy preparation includes: sorting and cleaning the waste ceramic fiber after drying, crushing and grinding to a particle size of 100 μm, injecting nitrogen 50 sccm in a vacuum reaction chamber, plasma treatment power 700 W, time 15 minutes, obtaining an active surface enhanced ceramic particle, and mixing with metal powder to smelt into an alloy.

[0157] The raw material composition of the molten steel in step one is:

[0158] C: 3.0%, Si: 0.5%, Mn: 0.5%, Cr: 0.6%, Ni: 0.2%, Ti: 0.02%, B: 0.002%, balance iron;

[0159] The smelting process includes: after adding raw materials in the smelting furnace, heating to the target temperature at 15°C / min, holding for 40 minutes, using an electromagnetic stirrer to stir at a speed of 100 r / min to ensure uniform composition.

[0160] The specific parameters of the multi-component modified alloy added in step two are:

[0161] The addition temperature is controlled at 1580°C, the stirring speed is 150 r / min, and the stirring time is 25 minutes;

[0162] The stirring equipment is a variable frequency mechanical stirrer with a power of 10 kW, which ensures that the alloy is fully dissolved and reacts with the molten steel;

[0163] When the addition amount is 1.0%, the molten steel fluidity improvement rate reaches 30%, and the mold filling capacity is improved;

[0164] The multi-component modified alloy is added in the form of particles with a particle size of ≤100 μm, and is uniformly sprayed into the molten pool through a pneumatic conveying system.

[0165] The specific vacuum environment for modification treatment in step three is:

[0166] The vacuum degree is set to 1× Pa, nitrogen injection rate 30 sccm, treatment time 10 minutes;

[0167] Or inert gas protection uses argon, flow rate 40 L / min, covers the surface of the molten steel;

[0168] The modification treatment process includes: using a spectrometer to monitor the oxygen activity of the molten steel online, and terminating the treatment when the oxygen activity decreases from the initial 30 PPM to ≤10 PPM.

[0169] The purification effect reduces non-metallic inclusions by ≥40%, reduces P content from 0.025% to ≤0.015%, and reduces S content from 0.030% to ≤0.020%.

[0170] The mold parameters for casting in step four are as follows:

[0171] The mold preheating temperature is 900°C, and a boron nitride coating is applied to the surface to reduce mold sticking;

[0172] The casting temperature is 1460°C, the casting speed is 20 cm / s, and the mold filling time is ≤60 seconds;

[0173] The casting process includes using an inclined casting system, designing the sprue as a cone, and ensuring smooth mold filling with a casting pressure of 0.5 MPa;

[0174] After forming, the wear-resistant steel ball has a diameter range of 150 mm, a surface roughness Ra≤3.2 μm, and no shrinkage or cold shut defects.

[0175] The specific operations of solution treatment and cooling in step five include:

[0176] Air cooling uses a forced air cooling system with a wind speed of 10 m / s and a cooling rate of 100°C / min to 200°C;

[0177] Or water quenching uses room temperature water with a quenching time of 30 seconds and a cooling rate of ≥200°C / min;

[0178] The tempering treatment after solution treatment and cooling is carried out at 250°C for 1.5 hours in a nitrogen atmosphere;

[0179] The wear-resistant steel ball after solution treatment and cooling has no internal cracks;

[0180] Solution strengthening increases the matrix hardness by HRC 10 units.

[0181] The multi-element modification alloy needs to be dried and pretreated before being added, and the specific operations include: placing the alloy powder in a drying device and treating it at 300°C for 2 hours to remove adsorbed moisture.

[0182] The process also includes a post-processing step:

[0183] The wear-resistant steel ball after cooling is subjected to shot peening treatment with a shot peening pressure of 0.6 MPa, a steel shot diameter of 1.0 mm, and a time of 10 minutes;

[0184] Then the hardness, size, and roundness are detected, and the qualified products are coated with rust-proof oil;

[0185] Shot peening increases the surface compressive stress by 300 MPa and increases the fatigue life by 20%.

[0186] The detection criteria are: hardness HRC≥55, deviation between core and surface≤2HRC, diameter tolerance±0.5mm, and out-of-roundness≤3%.

[0187] The performance indicators of the wear-resistant steel ball include:

[0188] The volume hardness HRC is 62, the unit wear is 90g / t, the out-of-roundness is≤3%, and the steel ball remains round when the diameter is≤10mm;

[0189] The metallographic structure shows that the carbides are uniformly distributed without continuous network structure.

[0190] The performance is verified through comparative tests: the oxygen activity decreases from 25PPM to 8PPM after use, the casting time is shortened by 30%, the P content is 0.010%, the S content is 0.016%, and the impact toughness is≥15J / cm².

[0191] Comparative Example 1, the difference between this comparative example and Example 1 is that the multi-alloying modifier in this comparative example does not contain RE, MnN and CrN components.

[0192] Comparative Example 2, the difference between this comparative example and Example 1 is that the multi-alloying modifier in this comparative example is not treated in a vacuum or inert gas protection environment, but in a normal pressure air environment.

[0193] Comparative Example 3, the difference between this comparative example and Example 1 is that the metal mold is not preheated during the casting process, but directly cast at room temperature.

[0194] Comparative Example 4, the difference between this comparative example and Example 1 is that the alloy powder is not dried before the multi-alloying modifier is added.

[0195] The performance of the as-cast wear-resistant steel balls prepared in Examples 1-3 and Comparative Examples 1-4 is tested, and the test items and test methods are as follows:

[0196] The oxygen activity and impurity content test is carried out in an inert gas protection environment, using a direct-reading spectrometer, cutting the steel ball sample to excite plasma, and directly reading the oxygen, phosphorus and sulfur element content;

[0197] The volume hardness test is carried out using a Rockwell hardness tester, load 150kgf, diamond cone indenter, 5 test points are taken on the surface and core of the steel ball respectively, the indentation spacing is≥3 times the indentation diameter, the HRC value is recorded and the average value and deviation are calculated;

[0198] Abrasion performance test, using an abrasive wear testing machine, with quartz sand as the abrasive, particle size 0.5-1.0mm, load 1000g, rotation speed 200r / min, after 5000m of grinding, the mass loss of the steel ball was weighed, and the unit abrasion was calculated;

[0199] Out-of-roundness rate and dimensional stability test, using a three-coordinate measuring instrument, during the grinding of the steel ball to a diameter of ≤10mm, the diameter range of the ball was measured once every 2mm of wear, and the out-of-roundness rate percentage was calculated based on the initial diameter.

[0200] The test data of the wear-resistant steel balls prepared in Examples 1-3 and Comparative Examples 1-4 are recorded in the following table:

[0201] By comparing and analyzing the data in the table, it can be seen that the as-cast wear-resistant steel balls prepared by the process of Examples 1-3 have more excellent performance than the wear-resistant steel balls prepared by Comparative Examples 1-4, which shows that the multi-component modification alloy realizes deep deoxidation and impurity purification in the steel liquid melting stage through the synergistic effect of rare earth elements RE and alkaline metal components Ba and Ca, reduces the oxygen activity and reduces the residual non-metallic inclusions, at the same time, the solid solution strengthening mechanism of MnN and CrN refines the grain structure, forms a uniform and dense matrix structure, suppresses porosity and segregation defects, and improves the overall density and impact toughness of the wear-resistant steel ball. The modification treatment is carried out in a vacuum or inert gas protection environment, by controlling the matching of pressure and gas atmosphere, the active components of the multi-component modification alloy are fully dispersed and the surface reaction is activated, the flowability of the steel liquid is optimized and the filling capacity is strengthened, the turbulent interference and abnormal temperature gradient in the casting process are avoided, the solidification front is stably expanded, the shrinkage, cold shut and other forming defects are simultaneously eliminated, the homogenization and high integrity of the as-cast structure are realized. The synergistic regulation of solid solution treatment and cooling stage combined with the adsorption of moisture removal of alloy powder in the drying pretreatment process ensures the cold speed adaptability of the high temperature phase change process, and through the air cooling or water quenching strategy, the size characteristics of the steel balls of different diameters are matched, the generation of micro-cracks and the risk of carbide coarsening are suppressed, at the same time, the surface compressive stress distribution is enhanced after shot peening, the hardness consistency and fatigue life stability of the core and surface layer are synergistically improved, and the wear resistance and shape retention ability of the product are optimized.

[0202] By comparing and analyzing the relevant data in the table, it can be seen that the as-cast wear-resistant steel balls prepared by the production process of the present application not only have ultra-low oxygen activity and impurity content, but also have high bulk hardness and extremely low unit abrasion. Therefore, it is shown that the as-cast wear-resistant steel ball production process provided by the present application using a multi-component modification alloy has more significant technical advantages, and is more suitable for popularization and application in heavy wear conditions such as mining and cement.

[0203] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; it is not intended to exclude myriad other embodiments of the present application that other inventors can develop based on the same general inventive concepts embodied by the described embodiments. That is, although the present application is described in terms of particular embodiments and implementations, it is to be understood that the terminology used is for the purpose of descriptive clarity and that it should be taken in a descriptive sense and not a limiting sense.

[0204] While the embodiments of the application have been shown and described herein, it is to be understood that the application is not limited to these embodiments. Rather, numerous modifications, changes, substitutions, and alterations can be made therein without departing from the spirit and scope of the present application as defined by the appended claims and their equivalents.

Claims

1. A process for producing as-cast wear-resistant steel balls using a multi-element modified alloy, characterized in that: The following steps are involved: Step 1: Molten steel smelting: Place the raw materials in an electric arc furnace or induction furnace, heat to 1550-1650°C and smelt to obtain basic molten steel; Step 2: Adding a multi-element modified alloy to the smelted molten steel in an amount of 0.5-2.0% of the total weight of the molten steel, and stirring at 1500-1600°C for 10-30 minutes to uniformly disperse the alloy. The multi-element modified alloy comprises RE, Ba, Ca, MnN, CrN, and Mo, wherein RE is a rare earth element selected from at least one of the lanthanide metals. Step 3: Modification treatment, in vacuum or inert gas protection environment, control the pressure to 1× -1× Pa, treatment time 5-15 minutes, deep deoxidation and steel liquid purification; Step 4: Casting: Pour the treated molten steel into a metal mold preheated to 800-1000°C, with a casting temperature of 1420-1500°C and a casting speed of 10-30cm / s to form a wear-resistant steel ball casting; Step 5: Solution treatment and cooling: After casting, air cool or water quench to room temperature immediately, and then temper at 200-300 ° C for 1-2 hours to obtain a wear-resistant steel ball with uniform cast structure and no internal pores.

2. The process for producing as-cast wear-resistant steel balls using a multi-element modified alloy according to claim 1, characterized in that: The weight percentage composition of the multi-element modified alloy is: RE: 5-20%, Ba: 5-25%, Ca: 5-15%, MnN: 1-10%, CrN: 5-10%, Mo: 3-10%; The amount of rare earth elements added is 1% of the total alloy weight, and the balance is iron and unavoidable impurities; The alloy preparation includes: sorting, cleaning, drying and crushing waste ceramic fibers to a particle size of 80-100 μm, injecting 10-50 sccm of nitrogen into a vacuum reaction chamber, plasma processing at a power of 300-700 W for 7-15 minutes to obtain ceramic particles with enhanced active surfaces, and mixing them with metal powder to form an alloy.

3. The process for producing as-cast wear-resistant steel balls using a multi-element modified alloy according to claim 1, characterized in that: The raw material composition of the molten steel smelting in the step 1 is: C: 2.0-3.0%, Si: 0.3-0.5%, Mn: 0.4-0.5%, Cr: 0.5-0.6%, Ni: 0.1-0.2%, Ti: 0.01-0.02%, B: 0.001-0.002%, the balance is iron; The smelting process includes: after adding raw materials to the smelting furnace, heating to the target temperature at 10-15°C / min, keeping warm for 20-40 minutes, and using an electromagnetic stirrer to stir at a speed of 50-100r / min to ensure uniform composition.

4. The process for producing as-cast wear-resistant steel balls using a multi-element modified alloy according to claim 1, characterized in that: The specific parameters for adding the multi-element modified alloy in step 2 are: The addition temperature is controlled at 1520-1580°C, the stirring speed is 100-150r / min, and the stirring time is 15-25 minutes; The stirring equipment is a variable frequency mechanical stirrer with a power of 5-10kW to ensure that the alloy is fully dissolved and reacts with the molten steel; The multi-element modified alloy is added in the form of particles with a particle size of ≤100 μm and is evenly sprayed into the molten pool through a pneumatic conveying system.

5. The process for producing as-cast wear-resistant steel balls using a multi-element modified alloy according to claim 1, characterized in that: The vacuum environment for the modification treatment in step 3 is specifically: Vacuum setting 1× Pa, nitrogen injection rate 30 sccm, treatment time 10 min; Or the inert gas protection adopts argon gas with a flow rate of 20-40L / min to cover the surface of the molten steel; The modification process includes: using a spectrometer to monitor the oxygen activity of the steel liquid online, and terminating the treatment when the oxygen activity drops from an initial 20-30 PPM to ≤10 PPM.

6. The process for producing as-cast wear-resistant steel balls using a multi-element modified alloy according to claim 1, characterized in that: The mold parameters for the casting in step 4 are: The mold is preheated to 900°C and coated with boron nitride to reduce sticking. Casting temperature 1440°C-1460°C, casting speed 20cm / s, mold filling time ≤60 seconds; The casting process includes: using an inclined casting system, a conical gate design, and a casting pressure of 0.2-0.5 MPa to ensure that the molten steel fills the mold smoothly; The diameter of the formed wear-resistant steel ball is in the range of 50-150 mm, the surface roughness Ra is less than or equal to 3.2 μm, and there is no shrinkage cavity or cold shut defect.

7. The process for producing as-cast wear-resistant steel balls using a multi-element modified alloy according to claim 1, characterized in that: The specific operations of solution treatment and cooling in step 5 include: Air cooling uses a forced air cooling system with a wind speed of 5-10m / s and a cooling rate of 50-100°C / min to 200°C; Or water quenching uses room temperature water, quenching time is 10-30 seconds, cooling rate is ≥200°C / min; The solution treatment and the tempering treatment after cooling were carried out at 250°C for 1.5 hours in a nitrogen atmosphere. The wear-resistant steel ball after solution treatment and cooling has no internal cracks.

8. The process for producing as-cast wear-resistant steel balls using a multi-element modified alloy according to claim 1, characterized in that: The multi-element modified alloy needs to be dried before being added. The specific operation includes: placing the alloy powder in a drying device and treating it at a temperature of 200-300°C for 1-2 hours to remove adsorbed moisture.

9. The process for producing as-cast wear-resistant steel balls using a multi-element modified alloy according to claim 1, characterized in that: The process also includes a post-processing step: Shot peening is performed on the cooled wear-resistant steel balls with a shot peening pressure of 0.4-0.6 MPa, a steel shot diameter of 0.5-1.0 mm, and a time of 5-10 minutes; Then the hardness, size and roundness are tested and qualified products are coated with anti-rust oil; The shot peening treatment increases the surface compressive stress by 200-300 MPa; The testing standards are: hardness HRC ≥ 55, deviation between the center and the surface ≤ 2HRC, diameter tolerance ± 0.5mm, and out-of-roundness ≤ 3%.

10. The process for producing as-cast wear-resistant steel balls using a multi-element modified alloy according to claim 1, characterized in that: The performance indicators of the wear-resistant steel balls include: Volume hardness HRC 58-62, unit wear loss 70-90 g / ton, loss of roundness ≤3%, and it remains round when ground to a diameter ≤10 mm; The metallographic structure shows that carbides are evenly distributed and there is no continuous network structure; The above performance is verified by comparative tests: after use, the oxygen activity is reduced from 25PPM to 8PPM, the casting time is shortened by 30%, the P content is 0.010%, the S content is 0.016%, and the impact toughness is ≥15J / cm².

Images