CN109440001B - A kind of multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite and preparation method thereof - Google Patents

Abstract

The invention discloses a method for preparing a multi-component low-alloy wear-resistant cast steel containing nanocrystalline austenite, which adopts scrap steel, ferrosilicon, ferromanganese and ferrochromium as raw materials to smelt medium-carbon low-alloy steel. Micro-alloy composite treatment, casting to obtain multi-element low-alloy wear-resistant cast steel; and then subjected to ultra-high temperature, high temperature, medium-high temperature variable temperature quenching treatment to obtain multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite. After the multi-element low-alloy wear-resistant cast steel of the present invention is compounded by multi-element microalloying, the solidified structure is obviously refined, and after further variable temperature quenching treatment at ultra-high temperature, high temperature and medium high temperature, martensite and nanocrystalline austenite are obtained. The complex phase structure has the characteristics of high hardness, good wear resistance and good strength and toughness, and has a good use effect, and its popularization and application have good economic and social benefits.

Description

A kind of multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite and preparation method thereof

technical field

The invention belongs to the technical field of wear-resistant materials, relates to a multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite, and also relates to a preparation method of the above-mentioned multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite.

Background technique

Low-alloy wear-resistant cast steel has the advantages of simple production process and low production cost, and has wide application prospects in the field of wear-resistant materials.

In order to improve the comprehensive properties of low-alloy wear-resistant cast steel, the Chinese invention patent "A method for preparing low-alloy high-toughness wear-resistant cast steel by using an electric arc furnace" (application number CN201410241277.3, publication number CN103981449A, published on 2014.08.13) A method for preparing low-alloy, high-toughness and wear-resistant cast steel by using an electric arc furnace is disclosed. The method for tough and wear-resistant cast steel has few steps, high efficiency and low cost, and the prepared low-alloy cast steel has high hardness, good wear resistance and good toughness, and can be used in the fields of cement building materials, mining and coal-fired power. Workpieces used, such as mill liners, grate plates and blind plates, etc. These workpieces are not only affected by the impact force of the abrasive, but also by the friction of the abrasive, and are often broken due to insufficient toughness, and the phenomenon of rapid wear failure due to insufficient wear resistance. The high-toughness and wear-resistant low-alloy steel material prepared by the method can effectively prevent the fracture and rapid wear failure of the workpiece, and has few preparation processes, high efficiency and low cost, and has a good prospect of popularization and application. The Chinese invention patent "Method for preparing a low-alloy high wear-resistant cast steel plate" (application number CN201310040622.2, publication number CN103266276A, published on 2013.08.28) also discloses the preparation of a low-alloy high wear-resistant cast steel plate A method comprising the following components: C: 0.25-0.35 wt.%; Si: 0.9-1.6 wt.%; Mn: 0.3-1.8 wt.%; Cr: 0.7-1.0 wt.%; Mo: 0.15-0.3 wt. %; Ti: 0.05-0.35wt.%; Nb: 0.01-0.05wt.%; V: 0.05-0.25wt.%; RE: 0.01-0.1wt.%; P, S≤0.03wt.%, and the rest are Fe After each component is melted, it is cast and formed, and then the treated ingot is put into it to heat up. When the temperature reaches 1050 to 1070 ° C, the temperature is kept warm. After the heat preservation is completed, the ingot is placed in a salt bath furnace of 240 to 245 ° C. Insulation, and finally air-cooled. The casting and heat treatment process of the invention is relatively simple and easy to control, and the cost is low, and the prepared material has a good combination of strength and toughness. The Chinese invention patent "Low-alloy wear-resistant cast steel heat treatment process" (application number CN201310536283.7, publication number CN104611524A, published on 2015.05.13) also discloses a low-alloy wear-resistant cast steel heat treatment process, including the following steps: (1 ) Select scrap steel (and returning scrap steel castings) and cut them into suitable blocks. The block size depends on the capacity of the furnace. In general, the maximum size of the charge should not exceed one-third of the furnace diameter. Smelting in a 0.5t medium frequency induction furnace; (2) Among them, ferromanganese, ferrochromium, ferrosilicon, and metal manganese should be baked at 800°C (in a red-burning state), and the baking time should not be less than 3 hours , ferrosilicon powder and silicon calcium powder and other materials should be heated and dried at a temperature of 200 ℃ ~ 300 ℃, and the drying time should not be less than 3 hours. The optimized composition of the new wear-resistant cast steel: adding no more than 2.3% of Cr, the composition range of carbon is determined to be 0.25% to 0.35%, the composition range of silicon is determined to be 1.50% to 2.50%, the content of Mn is determined to be 0.80% to 1.20%, and the content of chromium is determined to be 1.5% to 2.5%. Strictly control the temperature at 1580-1600°C, use wax mold and resin sand for casting, and the pouring temperature is greater than 1480°C; (3) Heat the material in step (2) above the critical temperature (Ac3), generally Ac3+75°C ～Ac3+100℃, keep the temperature for 30min～60min, dissolve the carbides and homogenize the austenite, and conduct air cooling at a rate greater than the critical cooling rate; (4) heat the material in step (3) at a temperature below Ac1 , heat preservation, generally tempering at 200 ℃ ~ 300 ℃ for 2h and cooling at an appropriate speed. The Chinese invention patent "A low alloy wear-resistant cast steel material and its preparation method" (application number CN201410271029.3, publication number CN104046893A, published on 2014.09.17) also discloses a low alloy wear-resistant cast steel material and its preparation method, the material has the following alloying elements and mass percentages: C: 0.2-0.4%, Si: 0.4-1.0%, Mn: 0.8-1.3%, Ni: 0.3-0.7%, Mo: 0.3%-0.5%, Nb : 0.03%-0.06%, the rest is Fe. The method has the following processes and steps: a. the raw materials are prepared by arc melting to prepare the alloy, and the alloy is annealed by high temperature diffusion; the alloy structure is ferrite, pearlite and a small amount of granular bainite; b. The annealed sample is normalized, and the Brinell hardness after normalizing reaches 220-290HBS; the normalized sample is tempered at 590 ℃, and the Brinell hardness ≥200HBS, tensile strength ≥550MPa, and elongation are obtained after tempering. ≥15%, low alloy wear-resistant cast steel material with friction rate ≤2.7×10 ^-5 mg/Nm. The material of the invention is suitable for wear-resistant parts of mining machinery, and has economic advantages such as excellent comprehensive mechanical properties, wide application range, low cost and the like. The Chinese invention patent "An economical low-alloy wear-resistant cast steel and its heat treatment process" (application number CN201310568551.3, publication number CN103556053A, publication date 2014.02.05) also discloses an economical low-alloy wear-resistant cast steel, It has the following composition and mass percentage: C: 0.10-0.30%, Mn: 0.5-1.5%, Ni: 0.3-1.0%, Nb: 0.01-0.05%, Si≤0.5%, P≤0.03%, S≤0.03% , the remainder is Fe and inevitable impurities. Its room temperature structure is ferrite and pearlite, and the content of pearlite is 20-30%. Its room temperature tensile strength is 540-580MPa, and its elongation is above 20%. It is obtained by adopting the traditional conventional smelting process, smelting through ingredients, casting and forming, and then normalizing at 850-900°C and tempering at 560-620°C. The Chinese invention patent "Multi-element low-alloy wear-resistant cast steel and its preparation method" (application number CN201310271443.X, publication number CN103397278A, publication date 2013.11.20) also discloses a multi-element low-alloy wear-resistant cast steel. The composition and its mass percentage are: carbon 0.20-0.26, manganese 1.15-1.35, silicon 1.75-1.90, phosphorus≤0.040, sulfur≤0.040, nickel 0.60-0.75, vanadium 0.25-0.35, Mo0.03-0.05, Zn0.58- 0.91, In0.2-0.3, As0.15-0.18, Sb0.05-0.06, Bi0.09-0.12, the matrix is iron. The invention has good mechanical and mechanical properties, uses low-cost silicon and manganese as main alloy elements, and can manufacture anti-wear parts such as ball mill lining plates and excavator bucket teeth. The Chinese invention patent "A low-alloy high wear-resistant cast steel" (application number CN201310040624.1, publication number CN103060705A, published on 2013.04.24) also discloses a low-alloy high wear-resistant cast steel, comprising the following components: C : 0.25-0.35wt.%; Si: 0.9-1.6wt.%; Mn: 0.3-1.8wt.%; Cr: 0.7-1.0wt.%; Mo: 0.15-0.3wt.%; Ti: 0.05-0.35wt.% %; Nb: 0.01-0.05wt.%; V: 0.05-0.25wt.%; RE: 0.01-0.1wt.%; P, S≤0.03wt.%, the rest are Fe and inevitable impurities. The invention is simple to prepare and has good strength and toughness.

The Chinese invention patent "A preparation method of low-alloy high wear-resistant cast steel" (application number CN201310040604.4, publication number CN103060704A, publication date 2013.04.24) also discloses a preparation method of low-alloy high wear-resistant cast steel, Contains the following components: C: 0.25-0.35 wt. %; Si: 0.9-1.6 wt. %; Mn: 0.3-1.8 wt. %; Cr: 0.7-1.0 wt. %; Mo: 0.15-0.3 wt. %; Ti: 0.05-0.35wt.%; Nb: 0.01-0.05wt.%; V: 0.05-0.25wt.%; RE: 0.01-0.1wt.%; P, S≤0.03wt.%, the rest are Fe; the After each component is melted, it is cast and formed, and then the treated casting is put into it to heat up. When the temperature reaches 1050-1070 ℃, it is kept warm. After the heat preservation is completed, the casting is put into a 240-245 ℃ salt bath furnace for heat preservation. Air-cooled. The casting and heat treatment process of the invention is relatively simple and easy to control, and the cost is low, and the prepared material has a good combination of strength and toughness. The Chinese invention patent "A high-strength, cheap and low-alloy wear-resistant cast steel" (application number CN201110425482.1, publication number CN102517499A, publication date 2012.06.27) also discloses a kind of silicon and manganese as the main alloying elements, which can be used to manufacture ball mills Low-cost high-strength wear-resistant cast steel for wear-resistant parts such as lining plates and excavator bucket teeth. The chemical composition and mass percentage of the cast steel are: C: 0.2-0.6; Si: 0.5-1.5; Mn: 0.5 -1.5; Cr: 0.5-1.5; Ti: <0.20; RE: <0.20; B: <0.015; Ca: <0.15; Tempered at 200±10℃, the tensile strength is greater than 1550MPa, the impact toughness is greater than 90J/cm ² , the fracture toughness is greater than 80Mpa.m ^1/2 , and the hardness is greater than 52HRC. The Chinese invention patent "A boron-containing low-alloy wear-resistant steel for pumps" (application number CN201110324456.X, publication number CN102367558A, publication date 2012.03.07) also discloses a boron-containing low-alloy wear-resistant steel for pumps, by weight The percentage of chemical composition (wt.%) is: C, 0.33; Mn, 1.20; Si, 1.30; Cr, 1.35; Mo, 0.30; Ni, 0.40; N, 0.05; The rest is Fe and inevitable impurities. The pump of the invention is made of resin sand for low-alloy wear-resistant steel castings containing boron. Boron-containing multi-element low-alloy wear-resistant cast steel. The invention has the advantages of high hardness, good toughness effect, high wear resistance, certain corrosion resistance, simple production process, low production cost and the like. The Chinese invention patent "A Low-alloy Mn-based Bainite Wear-resistant Cast Steel" (Application No. CN201110424710.3, Publication No. CN102517505A, published on June 27, 2012) also discloses a low-alloy Mn-based bainite wear-resistant cast steel Steel, the chemical composition and mass percentage of the cast steel are: C: 0.32-0.41; Si: 0.22-0.23; Mn: 0.46-0.62; Cr: 0.99-1.03; Mo: 0.49-0.54; B: 0.0024- 0.0040, the cast steel is air-cooled after being austenitized at 900°C, and then tempered at a low temperature of 220°C, its tensile strength is ≥2020MPa, hardness: 51-54HRC, elongation ≥5.2%, unnotched impact toughness: 80- 160J/cm ² , this cast steel can be used to manufacture wear-resistant parts for grinding and pulverizing equipment in various mining, building materials, power generation and other industries, such as coal washing machine tooth plates, tooth bars, impact hammers, etc. Various large diameter transmission wear-resistant pipes used. The Chinese invention patent "A Preparation Method of Low-alloy Manganese-based Tempered Martensitic Wear-resistant Cast Steel" (Application No. CN201010228506.X, Publication No. CN101880828A, published on 2010.11.10) also discloses a low-alloy manganese-based cast steel A preparation method of fire martensitic wear-resistant cast steel belongs to the technical field of preparation of low-alloy wear-resistant cast steel. The invention adopts Mn as the main alloy element, adds a small amount of Si, Cr, Cu, B and rare earth elements (La, Ce, Nb, Pr) and other alloy elements, and the rest is Fe. It is smelted by conventional steelmaking process. After casting, it is austenitized and then water quenched, then heated, kept warm, and tempered at low temperature. The wear-resistant cast steel produced by the invention has a tempered martensite structure after water quenching and tempering. The tensile strength of cast steel Rm>1800MPa, the specified non-proportional elongation strength Rp0.2>1600MPa, the elongation after fracture A>5%, the unnotched impact toughness a _k >150J/ ^cm2 , the U-notch impact energy a _KU > 20J/cm ² . The wear-resistant cast steel has few alloy elements, excellent strength, toughness and wear resistance, simple process and low cost, and can be used to manufacture wear-resistant cast steel parts such as bucket teeth, hammer heads, tooth plates, lining plates, track shoes and the like. The Chinese invention patent "Preparation Process of Low-Alloy Wear-resistant Cast Steel Without High-temperature Heat Treatment" (Application No. CN200510018473.5, Publication No. CN1667136A, published on 2005.09.14) also discloses the preparation of a low-alloy wear-resistant cast steel without high-temperature heat treatment It is a low-alloy wear-resistant cast steel with low energy consumption and high mechanical properties. In the invention, a trace or a small amount of elements that can greatly shift the heat treatment C curve to the right are added to the alloy ingredients. Inject the qualified molten steel into the casting mold to control the solidification temperature of the casting. When the temperature of the casting falls to a certain value, the casting is taken out from the casting mold and quenched into water; when the temperature drops below 100 °C, the casting is taken out of the water. ; Tempering at 200 ~ 300 ℃ temperature. The invention removes the high temperature heat treatment, which can save a lot of electric energy or fuel; can save the high temperature heat treatment equipment; greatly improve the working conditions of workers; avoid the oxidation burning loss of alloy materials in the high temperature heat treatment process; Improve labor productivity. It can reduce the loss of metal materials; reduce the pollution of heat treatment to the environment.

However, the matrix structure of various low-alloy wear-resistant cast steels that have been successfully developed at present is mostly martensite matrix, which has the characteristics of high hardness and good wear resistance, but martensite is brittle, which leads to low alloy wear resistance. Cast steel has low plasticity and poor toughness.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation method of multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite, which solves the problem of low plasticity and poor toughness of the existing low-alloy wear-resistant cast steel mainly based on martensite matrix. The problem.

Another object of the present invention is to provide a multi-component low-alloy wear-resistant cast steel containing nano-crystalline austenite prepared by the above-mentioned preparation method of the multi-component low-alloy wear-resistant cast steel containing nano-crystalline austenite.

The technical scheme adopted in the present invention is, a preparation method of multi-element low alloy wear-resistant cast steel containing nanocrystalline austenite, using scrap steel, ferrosilicon, ferromanganese and ferrochrome as raw materials, smelting medium carbon low alloy, In the process, multi-component micro-alloy composite treatment is carried out, and multi-component low-alloy wear-resistant cast steel is obtained by pouring; steel.

The present invention is also characterized in that,

A preparation method of multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite, which is specifically implemented according to the following steps:

Step 1, using scrap steel, ferrosilicon, ferromanganese and ferrochromium as raw materials, smelting medium carbon low alloy steel in an electric furnace, and then discharging the molten steel obtained by smelting into a ladle, and the ladle is pre-added with multi-component alloy particles;

Step 2: After slag removal and standing, the molten steel in the ladle is cooled down, and the molten steel is poured into the mold. When the temperature of the casting in the mold is lower than 400°C, the casting is taken out, and the multi-element low alloy resistant material is obtained after grinding and sand cleaning. Grinding steel castings;

In step 3, the multi-element low-alloy wear-resistant cast steel castings obtained in step 2 are sequentially subjected to ultra-high temperature, high temperature, and medium-high temperature variable temperature quenching treatment to obtain multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite.

The chemical composition and mass fraction of molten steel in the electric furnace in step 1 are controlled at 0.28-0.37%C, 0.54-0.71%Mn, 1.55-1.74%Si, 1.04-1.28%Cr, <0.032%P, <0.027%S, For the remainder of Fe, the sum of the above chemical composition mass fractions is 100%.

In step 1, the molten steel is heated to 1658-1674° C. before the molten steel is released to the ladle.

The size of the multicomponent alloy particles in step 1 is 3.5-6.3 mm.

In step 1, the added amount of multi-element alloy particles accounts for 3.1-3.4% of the mass fraction of molten steel entering the ladle, and the chemical composition and mass fraction of multi-element alloy particles are 5.57-6.22% Ce, 3.85-4.39% Ti, 2.83-3.17% N, 2.04-2.65%V, 1.68-1.87%Ta, 12.06-12.71%Ba, 5.14-5.68%Ca, 18.33-19.27%Al, 1.62-1.85%Mg, balance Si, the sum of the above chemical composition mass fractions is 100% .

In step 2, when the molten steel temperature drops to 1502-1527° C., the molten steel is poured into the mold.

In step 3, the ultra-high temperature is 1050-1065°C, the high-temperature temperature is 900-915°C, and the medium-high temperature is 195-210°C.

The variable temperature quenching treatment in step 3 is specifically: heating the multi-element low-alloy wear-resistant cast steel casting obtained in step 2 to 1050-1065° C. in a furnace, and after holding for 15-18 minutes, the furnace is cooled to a temperature of 980-995° C., After 25-30 minutes of heat preservation, it is discharged into a pool with a water temperature of 20-32°C for water cooling; when the surface temperature of the casting reaches 550-630°C, the casting is taken out from the pool and immediately enters the heating furnace with a temperature greater than 500°C. Reheat to 900-915°C, keep warm for 100-120 minutes, and put it into a pool with a water temperature of 25-35°C for water cooling; when the surface temperature of the casting is 190-210°C, take out the casting from the pool and immediately enter the heating furnace Reheat to 195-210°C, hold for 240-300 minutes, cool down the furnace to a temperature lower than 120°C, and air-cool to room temperature.

Another technical solution adopted in the present invention is to use the above-mentioned method to prepare the multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite.

The beneficial effects of the present invention are:

1. The multi-element low-alloy wear-resistant cast steel of the present invention does not contain expensive alloying elements such as nickel, molybdenum, and copper, and the production cost is relatively low;

2. After the multi-element low-alloy wear-resistant cast steel of the present invention is subjected to multi-element microalloy composite treatment, the solidified structure is obviously refined. After further ultra-high temperature, high temperature and medium-high temperature variable temperature quenching treatment, martensite and nanocrystalline austenite can be obtained. the complex phase organization;

球磨机衬板用于研磨铁矿石，使用后硬度提高4-6HRC。3. The multi-element low-alloy wear-resistant cast steel of the present invention has the characteristics of high hardness, good wear resistance and good strength and toughness, wherein the tensile strength reaches 2190-2240Mpa, the hardness is greater than 52HRC, the impact toughness a _ku is greater than 120J/cm ² , and the extension The rate is greater than 35%, and the material of the present invention has a good work hardening effect, which is used in production

The ball mill liner is used to grind iron ore, and the hardness is increased by 4-6HRC after use.

Description of drawings

Fig. 1 is the metallographic microstructure of the multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite prepared by the present invention, wherein Fig. a is a low magnification structure diagram, and Fig. b is a high magnification structure diagram;

2 is a transmission electron microscope photograph of the multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite prepared by the present invention.

Detailed ways

The present invention will be described in detail below with reference to specific embodiments.

A method for preparing a multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite of the present invention is specifically implemented according to the following steps:

Step 1, using scrap steel, ferrosilicon, ferromanganese and ferrochromium as raw materials, smelting in an electric furnace, and controlling the chemical composition and mass fraction of molten steel in the furnace to be 0.28-0.37%C, 0.54-0.71%Mn, 1.55-1.74% %Si, 1.04-1.28%Cr, <0.032%P, <0.027%S, the balance Fe, the sum of the above chemical composition mass fractions is 100%; then the molten steel in the furnace is heated to 1658-1674 ℃, and the molten steel is released from the furnace To the ladle, the ladle is pre-added with multi-component alloy particles with a particle size of 3.5-6.3mm.

The added amount of multi-element alloy particles accounts for 3.1-3.4% of the mass fraction of molten steel entering the ladle. The chemical composition and mass fraction of multi-element alloy particles are 5.57-6.22% Ce, 3.85-4.39% Ti, 2.83-3.17% N, 2.04-2.65 %V, 1.68-1.87%Ta, 12.06-12.71%Ba, 5.14-5.68%Ca, 18.33-19.27%Al, 1.62-1.85%Mg, balance Si, the sum of the above chemical composition mass fractions is 100%.

Step 2: After the molten steel in the ladle is slag-scraped and allowed to stand, when the temperature drops to 1502-1527°C, pour the molten steel into the mold. Grinding and cleaning to obtain multi-element low-alloy wear-resistant cast steel.

Step 3, Heat Treatment:

The multi-element low-alloy wear-resistant cast steel castings obtained by grinding and sand cleaning in step 2 are heated to 1050-1065 ° C with the furnace, and after holding for 15-18 minutes, the furnace is cooled to a temperature of 980-995 ° C, and after holding for 25-30 minutes After the casting surface temperature reaches 550-630 ℃, take out the casting from the pool and immediately enter the heating furnace with a temperature greater than 500 ℃ to reheat to 900-915 ℃ ℃, after 100-120 minutes of heat preservation, it is discharged into a pool with a water temperature of 25-35 ℃ for water cooling; when the surface temperature of the casting is 190-210 ℃, take out the casting from the pool, and immediately enter the heating furnace to reheat to 195-210 ℃, after holding for 240-300 minutes, the furnace is cooled to a temperature lower than 120 ℃, and the furnace is air-cooled to room temperature, and the multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite can be obtained.

The invention is a multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite, which is smelted in an electric furnace, has high efficiency and is easy to operate. In the process of molten steel smelting, cheap scrap steel, ferrosilicon, ferromanganese and ferrochromium are used as the main raw materials, and 0.54-0.71% Mn, 1.55-1.74% Si, 1.04-1.28% Cr are added to it. Dissolved in the matrix, it can improve the solid solution strengthening ability of the matrix, and it is convenient to obtain martensite structure after water-cooling quenching. In order to obtain a lath martensite structure with good strength and toughness, the carbon content in the molten steel is controlled at 0.28-0.37%C. In addition, in order to improve the toughness of cast steel, the content of phosphorus and sulfur is strictly limited, where P<0.032% and S<0.027%. Then the molten steel in the furnace is heated to 1658-1674 ℃, which can further reduce the harmful gases and inclusions in the molten steel. In addition, before the molten steel enters the ladle, multi-component alloy particles with a particle size of 3.5-6.3mm are pre-added in the ladle, and the amount of multi-component alloy particles added accounts for 3.1-3.4% of the mass fraction of the molten steel entering the ladle. The chemical composition of the multi-component alloy particles and its The mass fractions are 5.57-6.22%Ce, 3.85-4.39%Ti, 2.83-3.17%N, 2.04-2.65%V, 1.68-1.87%Ta, 12.06-12.71%Ba, 5.14-5.68%Ca, 18.33-19.27%Al , 1.62-1.85%Mg, the remainder Si, the sum of the above chemical composition mass fractions is 100%. The addition of the above-mentioned multi-component alloy particles can significantly refine the solidified structure, which is beneficial to obtain the as-cast fine-grained structure, and promotes the obtaining of nanocrystalline austenite after heat treatment. After the molten steel in the ladle is slag removed and left to stand, when the temperature drops to 1502-1527°C, pour the molten steel into the mold. After sanding, heat treatment is performed.

On this basis, the polished and sand-cleaned castings are heated to 1050-1065°C with the furnace and kept for 15-18 minutes to improve the stability of high-temperature austenite. The furnace is cooled to a temperature of 980-995°C, and after 25-30 minutes of heat preservation, it is discharged into a pool with a water temperature of 20-32°C for water cooling. When the surface temperature of the casting reaches 550-630°C, the casting is taken out from the pool to obtain the Markov. In order to refine the austenite structure, the present invention needs to take out the casting from the pool after the surface temperature of the casting reaches 550-630 °C, and immediately enter the furnace for heating with a temperature greater than 500 °C The furnace is reheated to 900-915 °C, and after 100-120 minutes of heat preservation, it is discharged into a pool with a water temperature of 25-35 °C for water cooling to obtain a composite structure of martensite and nanocrystalline austenite, which can maintain Under the premise of high hardness and excellent wear resistance, multi-element low-alloy cast steel has good strength and toughness and high fatigue resistance. In addition, when the surface temperature of the casting is 190-210°C, take out the casting from the pool, immediately enter the heating furnace and reheat it to 195-210°C, and perform tempering treatment, which can stabilize the structure, eliminate internal stress, and make the multi-component low alloy wear-resistant. The comprehensive performance of cast steel is further improved. After holding for 240-300 minutes, the furnace is cooled to a temperature lower than 120 ℃, and the furnace is air-cooled to room temperature, and the multi-component low-alloy wear-resistant cast steel containing nanocrystalline austenite with excellent comprehensive properties can be obtained.

The present invention will be described in further detail below in conjunction with the examples, but the present invention is not limited to the following examples.

Example 1:

A method for preparing multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite, adopting a 500 kg medium frequency induction electric furnace for smelting, and the specific process steps are:

①Use scrap steel, ferrosilicon, ferromanganese and ferrochromium as raw materials, first smelt medium-carbon low-alloy wear-resistant cast steel in an electric furnace, and control the chemical composition and mass fraction of molten steel in the furnace to 0.28%C, 0.71%Mn , 1.55% Si, 1.28% Cr, 0.030% P, 0.021% S, the balance Fe, the sum of the above chemical composition mass fractions is 100%, then the molten steel in the furnace is heated to 1658 ° C, and the molten steel is released to the ladle, the ladle The multi-component alloy particles with particle size of 3.5-6.3mm are pre-added, and the added amount of multi-component alloy particles accounts for 3.1% of the mass fraction of molten steel entering the ladle. The chemical composition and mass fraction of multi-component alloy particles are 5.57% Ce, 4.39% Ti, 2.83%N, 2.65%V, 1.68%Ta, 12.71%Ba, 5.14%Ca, 19.27%Al, 1.62%Mg, balance Si, the sum of the above chemical composition mass fractions is 100%; , After standing, when the temperature drops to 1502 ℃, pour the molten steel into the mold, when the temperature of the casting in the mold is lower than 400 ℃, take out the casting, and prepare for heat treatment after grinding and sand cleaning;

②The castings that have been polished and sand-cleaned in step ① are heated to 1065°C with the furnace, and after 15 minutes of heat preservation, the furnace is cooled to 995°C, and after 25 minutes of heat preservation, the castings are released from the furnace and put into a pool with a water temperature of 29-32°C. Water cooling, when the surface temperature of the casting reaches 595-630°C, the casting is taken out from the pool, and immediately enters the heating furnace with a temperature of 556-564°C and reheats to 915°C. After holding for 100 minutes, the water temperature is 34-35°C. Water cooling is carried out in a pool with a temperature of 205 °C. When the surface temperature of the casting is 205-210 °C, the casting is taken out from the pool, and immediately enters the heating furnace to reheat to 210 °C. At room temperature, multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite can be obtained, and its mechanical properties are shown in Table 1.

Example 2:

A preparation method of multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite, adopting 1500 kg medium frequency induction electric furnace for smelting, and the specific process steps are:

①Use scrap steel, ferrosilicon, ferromanganese and ferrochromium as raw materials, first smelt medium-carbon low-alloy wear-resistant cast steel in an electric furnace, and control the chemical composition and mass fraction of molten steel in the furnace to 0.37%C, 0.54%Mn , 1.74% Si, 1.04% Cr, 0.025% P, 0.020% S, the balance Fe, the sum of the above chemical composition mass fractions is 100%, then the molten steel in the furnace is heated to 1674 ° C, and the molten steel is released to the ladle, the ladle The multi-component alloy particles with particle size of 3.5-6.3mm are pre-added, and the added amount of multi-component alloy particles accounts for 3.4% of the mass fraction of molten steel entering the ladle. The chemical composition and mass fraction of multi-component alloy particles are 6.22% Ce, 3.85% Ti, 3.17%N, 2.04%V, 1.87%Ta, 12.06%Ba, 5.68%Ca, 18.33%Al, 1.85%Mg, balance Si, the sum of the above chemical composition mass fractions is 100%; , After standing, when the temperature drops to 1527℃, pour the molten steel into the mold. When the temperature of the casting in the mold is lower than 400℃, take out the casting from the box. After grinding and cleaning, it is ready for heat treatment;

②The castings that have been polished and sand-cleaned in step ① are heated to 1050°C in the furnace, and after 18 minutes of heat preservation, the furnace is cooled to 980°C, and after 30 minutes of heat preservation, the castings are put into a pool with a water temperature of 20-24°C. Carry out water cooling; when the surface temperature of the casting reaches 550-590 °C, take out the casting from the pool, immediately enter the heating furnace with a temperature of 522-527 °C and reheat it to 900 °C, and keep it for 120 minutes. Water cooling is carried out in a pool of 28°C; when the surface temperature of the casting is 195-203°C, the casting is taken out from the pool and immediately enters the heating furnace to reheat to 205°C. Air-cooled to room temperature, multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite can be obtained, and its mechanical properties are shown in Table 1.

Example 3:

A multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite and a preparation method thereof are smelted in a 1000 kg medium frequency induction electric furnace, and the specific process steps are:

①Use scrap steel, ferrosilicon, ferromanganese and ferrochromium as raw materials, first smelt medium-carbon low-alloy wear-resistant cast steel in an electric furnace, and control the chemical composition and mass fraction of molten steel in the furnace to 0.33%C, 0.59%Mn , 1.63% Si, 1.19% Cr, 0.029% P, 0.025% S, the remainder Fe, the sum of the above chemical composition mass fractions is 100%, then the molten steel in the furnace is heated to 1666 ° C, and the molten steel is released to the ladle, the ladle Multi-component alloy particles with particle size of 3.5-6.3mm are pre-added in the inner, and the amount of multi-component alloy particles added accounts for 3.2% of the mass fraction of molten steel entering the ladle. The chemical composition and mass fraction of multi-component alloy particles are 5.93% Ce, 4.18% Ti, 2.96%N, 2.51%V, 1.80%Ta, 12.57%Ba, 5.42%Ca, 18.71%Al, 1.76%Mg, balance Si, the sum of the above chemical composition mass fractions is 100%; , After standing, when the temperature drops to 1516 ℃, pour the molten steel into the mold, when the temperature of the casting in the mold is lower than 400 ℃, unpack the casting, and prepare for heat treatment after grinding and sand cleaning;

②The castings that have been polished and sand-cleaned in step ① are heated to 1060°C with the furnace, and after 16 minutes of heat preservation, the furnace is cooled to 990°C, and after 28 minutes of heat preservation, they are released from the furnace and put into a pool with a water temperature of 25-28°C. Carry out water cooling; when the surface temperature of the casting reaches 575-592 °C, take out the casting from the pool, immediately enter the furnace with a temperature of 538-549 °C and reheat it to 910 °C, and keep it for 110 minutes. Water cooling is carried out in a pool of 31°C; when the surface temperature of the casting is 190-195°C, the casting is taken out from the pool and immediately enters the heating furnace to be reheated to 195°C. Air-cooled to room temperature, multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite can be obtained, and its mechanical properties are shown in Table 1.

Example 4:

A multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite and a preparation method thereof are smelted in a 500 kg medium frequency induction electric furnace, and the specific process steps are:

①Use scrap steel, ferrosilicon, ferromanganese and ferrochromium as raw materials, first smelt medium-carbon low-alloy wear-resistant cast steel in an electric furnace, and control the chemical composition and mass fraction of molten steel in the furnace to 0.30%C, 0.56%Mn , 1.60% Si, 1.10% Cr, 0.031% P, 0.022% S, the balance Fe, the sum of the above chemical composition mass fractions is 100%, then the molten steel in the furnace is heated to 1660 ° C, and the molten steel is released to the ladle, the ladle The multi-component alloy particles with particle size of 3.5-6.3mm are pre-added in it. The amount of multi-component alloy particles added accounts for 3.3% of the mass fraction of molten steel entering the ladle. The chemical composition and mass fraction of multi-component alloy particles are 5.72% Ce, 3.96% Ti, 2.90%N, 2.17%V, 1.73%Ta, 12.26%Ba, 5.29%Ca, 18.54%Al, 1.70%Mg, balance Si, the sum of the above chemical composition mass fractions is 100%; , After standing, when the temperature drops to 1510℃, pour the molten steel into the mold. When the temperature of the casting in the mold is lower than 400℃, take out the casting from the box. After grinding and cleaning, it is ready for heat treatment;

②The casting that has been polished and cleaned in step ① is heated to 1055°C in the furnace, after 17 minutes of heat preservation, the furnace is cooled to 985°C, and after 29 minutes of heat preservation, it is released from the furnace and put into a pool with a water temperature of 22-25°C. Carry out water cooling; when the surface temperature of the casting reaches 567-579°C, take out the casting from the pool, immediately enter the furnace with a temperature of 525-537°C and reheat it to 905°C, and keep it for 117 minutes, the water temperature is 27- Water cooling is carried out in a pool at 29°C; when the surface temperature of the casting is 191-199°C, the casting is taken out from the pool and immediately enters the heating furnace to reheat to 200°C. Air-cooled to room temperature, multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite can be obtained, and its mechanical properties are shown in Table 1.

Example 5:

A multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite and a preparation method thereof are smelted in a 1500 kg medium frequency induction electric furnace, and the specific process steps are:

①Use scrap steel, ferrosilicon, ferromanganese and ferrochromium as raw materials, first smelt medium-carbon low-alloy wear-resistant cast steel in an electric furnace, and control the chemical composition and mass fraction of molten steel in the furnace to 0.35%C, 0.65%Mn , 1.70% Si, 1.25% Cr, 0.027% P, 0.024% S, the balance Fe, the sum of the above chemical composition mass fractions is 100%, then the molten steel in the furnace is heated to 1670 ° C, and the molten steel is released to the ladle, the ladle The multi-element alloy particles with particle size of 3.5-6.3mm are pre-added, and the addition amount of multi-element alloy particles accounts for 3.25% of the mass fraction of molten steel entering the ladle. The chemical composition and mass fraction of multi-element alloy particles are 6.05% Ce, 4.23% Ti, 3.08%N, 2.35%V, 1.85%Ta, 12.38%Ba, 5.50%Ca, 18.93%Al, 1.81%Mg, balance Si, the sum of the above chemical composition mass fractions is 100%; , After standing, when the temperature drops to 1520 ℃, pour the molten steel into the mold, when the temperature of the casting in the mold is lower than 400 ℃, take out the casting, and prepare for heat treatment after grinding and sand cleaning;

②The casting that has been polished and cleaned in step ① is heated to 1062°C with the furnace, after 15 minutes of heat preservation, the furnace is cooled to 992°C, and after 24 minutes of heat preservation, it is released from the furnace and put into a pool with a water temperature of 29-31°C. Carry out water cooling; when the surface temperature of the casting reaches 605-625°C, take out the casting from the pool, immediately enter the heating furnace with a temperature of 545-555°C and reheat it to 912°C, and keep the temperature for 105 minutes. Water cooling is carried out in a pool of 32°C; when the surface temperature of the casting is 198-206°C, the casting is taken out from the pool and immediately enters the heating furnace to reheat to 207°C. Air-cooled to room temperature, multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite can be obtained, and its mechanical properties are shown in Table 1.

Table 1 Mechanical properties of multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite

As can be seen from the above table, the multi-element low-alloy wear-resistant cast steel prepared by the present invention has a tensile strength of 2190-2240Mpa, a hardness greater than 52HRC, an impact toughness a _ku greater than 120J/cm ² , an elongation greater than 35%, and a plasticity and The toughness is significantly improved compared to the existing low alloy wear-resistant cast steel.

Fig. 1 is the metallographic microstructure of the multi-element low-alloy wear-resistant cast steel prepared by the present invention (Fig. a is a low magnification structure, and Fig. b is a high magnification structure). It can be seen from the figure that the main structure of the ingot is lath martensite.

Fig. 2 is the transmission electron microscope photograph of the multi-element low-alloy wear-resistant cast steel prepared by the present invention. It can be seen from the figure that nano-austenite (shown by the arrow) is inlaid between the martensites, indicating that the method of the present invention is successful in the martensite. Nanocrystalline austenite was obtained in the intenite structure. The existence of nanocrystalline austenite is conducive to improving the toughness of cast steel. In addition, the nanocrystalline austenite is easily transformed into martensite with high hardness under the action of wear load during the wear process, which is conducive to promoting the wear resistance of cast steel. further improvement.

球磨机衬板用于研磨铁矿石，使用后硬度提高4-6HRC，本发明材料用于球磨机衬板，破碎机锤头和破碎壁，使用寿命比高锰钢提高350-400％，使用中无断裂、变形现象出现，推广应用具有良好的经济和社会效益。The multi-element low-alloy wear-resistant cast steel of the invention does not contain expensive alloy elements such as nickel, molybdenum and copper, and has lower production cost. After the multi-element low-alloy wear-resistant cast steel of the present invention is subjected to multi-element micro-alloy composite treatment, the solidified structure is obviously refined, and after further ultra-high temperature, high temperature and medium-high temperature variable temperature quenching treatment, a composite of martensite and nanocrystalline austenite can be obtained. phase organization. The multi-element low-alloy wear-resistant cast steel of the invention has the characteristics of high hardness, good wear resistance, good strength and toughness, and the like, wherein the tensile strength reaches 2190-2240Mpa, the hardness is greater than 52HRC, the impact toughness a _ku is greater than 120J/cm ² , and the elongation is greater than 35%, the material of the present invention also has a good work hardening effect, which is used for production

The ball mill liner is used for grinding iron ore, and the hardness is increased by 4-6HRC after use. The material of the present invention is used for the ball mill liner, the hammer head and the crushing wall of the crusher, and the service life is 350-400% higher than that of high manganese steel. The phenomenon of fracture and deformation appears, and its popularization and application have good economic and social benefits.

Claims (5)

1. a preparation method of multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite, is characterized in that, adopting scrap steel, ferrosilicon, ferromanganese and ferrochromium as raw materials, smelting medium carbon low alloy steel, in the smelting process Multi-component micro-alloy composite treatment is carried out, and multi-component low-alloy wear-resistant cast steel is obtained by pouring; Specifically, follow the steps below: Step 1, using scrap steel, ferrosilicon, ferromanganese and ferrochromium as raw materials, smelting medium carbon low alloy steel in an electric furnace, and then discharging the molten steel obtained by smelting into a ladle, and the ladle is pre-added with multi-component alloy particles; The chemical composition and mass fraction of the molten steel in the electric furnace are controlled at 0.28-0.37%C, 0.54-0.71%Mn, 1.55-1.74%Si, 1.04-1.28%Cr, <0.032%P, <0.027%S, the balance Fe, the sum of the above chemical composition mass fractions is 100%; The size of the multi-element alloy particles is 3.5-6.3mm, the added amount of the multi-element alloy particles accounts for 3.1-3.4% of the mass fraction of molten steel entering the ladle, and the chemical composition and mass fraction of the multi-element alloy particles are 5.57-6.22% Ce, 3.85-4.39%Ti, 2.83-3.17%N, 2.04-2.65%V, 1.68-1.87%Ta, 12.06-12.71%Ba, 5.14-5.68%Ca, 18.33-19.27%Al, 1.62-1.85%Mg, balance Si, the sum of the above chemical composition mass fractions is 100%; Step 2: After slag removal and standing, the molten steel in the ladle is cooled down, and the molten steel is poured into the mold. When the temperature of the casting in the mold is lower than 400°C, the casting is taken out, and the multi-element low alloy resistant material is obtained after grinding and sand cleaning. Grinding steel castings; In step 3, the multi-element low-alloy wear-resistant cast steel castings obtained in step 2 are successively subjected to the variable temperature quenching treatment of ultra-high temperature, high temperature, and medium high temperature, so as to obtain the multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite; The variable temperature quenching treatment is specifically as follows: heating the multi-element low-alloy wear-resistant cast steel castings obtained in step 2 to 1050-1065° C. in a furnace, holding for 15-18 minutes, cooling the furnace to a temperature of 980-995° C., and holding the temperature for 15-18 minutes. After 25-30 minutes, it is released into a pool with a water temperature of 20-32 °C for water cooling; when the surface temperature of the casting reaches 550-630 °C, the casting is taken out from the pool and immediately enters the heating furnace with a temperature greater than 500 °C to reheat. After heating to 900-915°C and holding for 100-120 minutes, it is discharged into a pool with a water temperature of 25-35°C for water cooling; when the surface temperature of the casting is 190-210°C, the casting is taken out from the pool, and immediately enters the heating furnace to regenerate. Heated to 195-210°C and kept for 240-300 minutes, then cooled in the furnace until the temperature was lower than 120°C, and air-cooled to room temperature. 2. the preparation method of a kind of multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite according to claim 1, is characterized in that, in described step 1, molten steel is heated up to 1658- 1674°C. 3. the preparation method of a kind of multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite according to claim 1, is characterized in that, in described step 2, when molten steel temperature drops to 1502-1527 ℃, will The molten steel is poured into the mold. 4. the preparation method of a kind of multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite according to claim 1, is characterized in that, in described step 3, ultra-high temperature temperature is 1050-1065 ℃, and high temperature temperature is 900 ℃ -915℃, medium and high temperature is 195-210℃. 5. The multi-element low-alloy wear-resistant cast steel containing nanocrystalline austenite obtained by the method of any one of claims 1-4.

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