阅读说明：本技术 一种高耐磨高铬白口铸铁及其制备方法 (High-wear-resistance high-chromium white cast iron and preparation method thereof ) 是由 李卫 易艳良 涂小慧 于 2021-05-25 设计创作，主要内容包括：本发明属于抗磨金属材料技术领域,具体涉及一种高耐磨高铬白口铸铁及其制备方法。该铸铁的化学成分,以质量分数计(wt％),包括：2～3C,0.5～1Si,0.5～1Mn,12～15Cr,0.3～0.5B,0.2～0.5Ni,0.2～0.4Ti,余量为Fe。本发明的高耐磨含硼高铬白口铸铁经中频感应电炉熔炼成形,进行淬火和回火处理,生成的马氏体呈现针片状,具有高硬度(63～65HRC)、高韧性(13.5～15.5J/cm～(2))和高耐磨性(较Cr15高铬铸铁提高35～45％),且残余应力较低(-180～-220MPa)。(The invention belongs to the technical field of wear-resistant metal materials, and particularly relates to high-wear-resistance high-chromium white cast iron and a preparation method thereof. The cast iron comprises the following chemical components in percentage by mass (wt%): 2-3C, 0.5-1 Si, 0.5-1 Mn, 12-15 Cr, 0.3-0.5B, 0.2-0.5 Ni, 0.2-0.4 Ti, and the balance Fe. The high-wear-resistance boron-containing high-chromium white cast iron is formed by smelting in a medium-frequency induction furnace, quenching and tempering are carried out, and the generated martensite is in a needle-shaped shape, has high hardness (63-65 HRC) and high toughness (13.5-15.5J/cm) 2 ) And high wear resistance (35-45% higher than Cr15 high-chromium cast iron),and the residual stress is lower (-180 to-220 MPa).)

1. The high-wear-resistance high-chromium white cast iron is characterized by comprising the following chemical components in percentage by mass: 2-3% of C, 0.5-1% of Si, 0.5-1% of Mn, 12-15% of Cr, 0.3-0.5% of B, 0.2-0.5% of Ni, 0.2-0.4% of Ti, and the balance of Fe.

2. The white cast iron with high wear resistance and high chromium content according to claim 1, wherein the chemical composition of the white cast iron with high wear resistance comprises the following components in percentage by mass: 2.08% of C, 0.57% of Si, 0.64% of Mn, 13.9% of Cr, 0.32% of B, 0.29% of Ni, 0.24% of Ti and the balance of Fe.

3. The white cast iron with high wear resistance and high chromium content according to claim 1, wherein the chemical composition of the white cast iron with high wear resistance comprises the following components in percentage by mass: 2.35% of C, 0.57% of Si, 0.59% of Mn, 13.2% of Cr, 0.37% of B, 0.27% of Ni, 0.25% of Ti and the balance of Fe.

4. The white cast iron with high wear resistance and high chromium content according to claim 1, wherein the chemical composition of the white cast iron with high wear resistance comprises the following components in percentage by mass: 2.19% of C, 0.53% of Si, 0.56% of Mn, 14.3% of Cr, 0.36% of B, 0.31% of Ni, 0.26% of Ti and the balance of Fe.

5. The white cast iron with high wear resistance and high chromium according to claim 1, characterized in that the residual stress of the white cast iron with high wear resistance is-180 to-220 MPa.

6. The white cast iron with high wear resistance and high chromium according to claim 1, wherein the hardness of the white cast iron with high wear resistance is 63-65 HRC.

7. The high-wear-resistance high-chromium white cast iron according to claim 1, wherein the impact toughness of the high-wear-resistance high-chromium white cast iron is 13.5-15.5J/cm²。

8. The method for preparing a high wear resistant high chromium white cast iron according to any one of claims 1 to 7, characterized by comprising the steps of:

(1) mixing 40-44% of waste steel, 8-9% of ferrochrome, 1-1.5% of ferromanganese, 1.5-3% of ferrotitanium, 42.5-49.5% of pure iron and 0.3-0.5% of ferroboron according to the mass ratio, filling the mixture into a smelting furnace, and heating to melt;

(2) crushing ferroboron into blocks with the particle size of less than 20mm, drying at 200-250 ℃, placing at the bottom of a casting ladle, and adding the ferroboron blocks into a smelting furnace by adopting a ladle-in-ladle flushing method;

(3) heating the smelting furnace to 1500-1550 ℃, adding a deoxidizer aluminum wire, and adding 0.2-0.5% pure nickel rods after furnace materials are completely melted;

(4) and when the temperature of the molten steel reaches 1350-1450 ℃, casting to obtain a casting, then preserving the heat of the casting at 900-1000 ℃ for 2-4 h to carry out quenching treatment, putting a PAG solution with the concentration of 3-10 wt% to cool to 150 ℃, then preserving the heat at 200-300 ℃ for 3-6 h to carry out tempering treatment, and carrying out air cooling to room temperature to obtain the white cast iron.

9. The method for preparing high-wear-resistance high-chromium white cast iron according to claim 8, wherein the chemical composition of each charge is as shown in table 1:

table 1 chemical composition of each charge in wt%

10. The method of claim 8, wherein the PAG solution is at a concentration of 3 wt%, 5 wt%, 7 wt% or 10 wt%.

Technical Field

The invention belongs to the technical field of wear-resistant metal materials, and particularly relates to high-wear-resistance high-chromium white cast iron and a preparation method thereof.

Background

Currently, the wear-resistant materials applied in industry are wear-resistant coating materials, wear-resistant ceramic materials, wear-resistant composite materials, wear-resistant metal materials and the like. The wear-resistant metal material is one of wear-resistant materials with wider engineering application at present because of the advantages of simple preparation process, low cost, high flexibility of part shapes and the like. At present, the wear-resistant metal materials mainly comprise manganese series wear-resistant steel, chromium series wear-resistant alloy steel, wear-resistant white cast iron and the like, and the manganese series wear-resistant steel, the chromium series wear-resistant alloy steel, the wear-resistant white cast iron and the like have respective characteristics. Among them, high-chromium white cast iron is a wear-resistant metal material which is relatively widely used. In daily production and life of people, the high-chromium white cast iron is widely applied to wear-resistant parts, such as crusher hammers, flour mill grinding rollers, ball mill grinding sections and the like.

Compared with other materials, the high-chromium white cast iron has excellent wear resistance and corrosion resistance, higher strength and toughness, low production cost and simple and convenient casting method. However, as shown in the ternary phase diagram of Fe-C-Cr, M distributed in the matrix in the form of isolated hexagonal rods or plates can be obtained only when the ratio of carbon to chromium is appropriate₇C₃And the carbide is obtained, and the time and the labor are consumed, and the production cost is increased. Relevant researches show that the element B is added into the high-chromium cast iron to obtain M with excellent stability and wear resistance₂B-type boride. Therefore, only M obtained by adding B element to high-chromium white cast iron₂The B-type boride is researched and analyzed, so that the toughness and the wear resistance of the high-chromium white cast iron can be improved.

However, in order to reduce the production cost of boron-containing high-chromium white cast iron, precious metal elements are often reduced or not added during the design of alloy components, so that the alloy has low hardenability and is difficult to be directly applied to thick-wall wear-resistant parts. Generally, the higher the hardness of a wear-resistant metal material, the better the wear resistance, and the hardness increase is mainly dependent on quenching treatment to obtain a matrix structure with better mechanical properties. However, the quenching process tends to cause large residual stresses inside the workpiece and stress concentrations in localized areas (corners, sharp corners, etc.). Due to M₇C₃And M₂B has intrinsic brittleness, and the cracking of the steel after quenching treatment is easy to cause by overlarge stress. Therefore, in industrial applications, it is necessary to obtain a martensite matrix structure with superior performance under relatively slow heat treatment cooling conditions. Currently, the research on boron-containing high-chromium white cast iron is mainly focused on M₇C₃And M₂B, toughening and morphology improvement, and the like, and the research on the regulation and control of the quenching cooling rate is quite few.

Disclosure of Invention

The invention aims to provide high-wear-resistance high-chromium white cast iron which has the advantages of high hardness, good impact toughness, simple preparation method process, short production period and low energy consumption.

The invention realizes the regulation and control of different cooling rates by using PAG (polyalkylene glycol) solutions with different concentrations (the cooling rate can be changed along with the change of the concentration of PAG), researches the influence of the cooling rate on the wear resistance and the mechanical property of the boron-containing high-chromium cast iron, and provides practical value for preparing the high-wear-resistance high-chromium white cast iron.

The purpose of the invention is realized by the following technical scheme:

the high-wear-resistance high-chromium white cast iron comprises the following chemical components in percentage by mass (wt%): 2-3% of C, 0.5-1% of Si, 0.5-1% of Mn, 12-15% of Cr, 0.3-0.5% of B, 0.2-0.5% of Ni, 0.2-0.4% of Ti, and the balance of Fe.

Preferably, the chemical composition of the high-wear-resistance high-chromium white cast iron comprises the following components in percentage by mass (wt%): 2.08% of C, 0.57% of Si, 0.64% of Mn, 13.9% of Cr, 0.32% of B, 0.29% of Ni, 0.24% of Ti and the balance of Fe.

Preferably, the chemical composition of the high-wear-resistance high-chromium white cast iron comprises the following components in percentage by mass (wt%): 2.35% of C, 0.57% of Si, 0.59% of Mn, 13.2% of Cr, 0.37% of B, 0.27% of Ni, 0.25% of Ti and the balance of Fe.

Preferably, the chemical composition of the high-wear-resistance high-chromium white cast iron comprises the following components in percentage by mass (wt%): 2.19% of C, 0.53% of Si, 0.56% of Mn, 14.3% of Cr, 0.36% of B, 0.31% of Ni, 0.26% of Ti and the balance of Fe.

Preferably, the residual stress of the high-wear-resistance high-chromium white cast iron is-180 MPa to-220 MPa.

Preferably, the hardness of the high-wear-resistance high-chromium white cast iron is 63-65 HRC.

Preferably, the impact toughness of the high-wear-resistance high-chromium white cast iron is 13.5-15.5J/cm²。

The preparation method of the high-wear-resistance high-chromium white cast iron comprises the following steps:

(1) mixing 40-44% of waste steel, 8-9% of ferrochrome, 1-1.5% of ferromanganese, 1.5-3% of ferrotitanium, 42.5-49.5% of pure iron and 0.3-0.5% of ferroboron according to the mass ratio, filling the mixture into a smelting furnace, and heating to melt;

(2) crushing ferroboron into blocks with the particle size of less than 20mm, drying at 200-250 ℃, placing at the bottom of a casting ladle, and adding the ferroboron blocks into a smelting furnace by adopting a ladle-in-ladle flushing method;

(3) heating the smelting furnace to 1500-1550 ℃, adding a deoxidizer aluminum wire, and adding 0.2-0.5% pure nickel rods after furnace materials are completely melted;

(4) and when the temperature of the molten steel reaches 1350-1450 ℃, casting to obtain a casting, then preserving the heat of the casting at 900-1000 ℃ for 2-4 h to carry out quenching treatment, putting a PAG solution with the concentration of 3-10 wt% to cool to 150 ℃, then preserving the heat at 200-300 ℃ for 3-6 h to carry out tempering treatment, and carrying out air cooling to room temperature to obtain the white cast iron.

In the preparation method, the sum of the mass percentages of the scrap steel, the ferrochrome, the ferromanganese, the ferrotitanium, the pure iron, the ferroboron and the pure nickel is 100 percent.

Preferably, the concentration of the PAG solution is 3 wt%, 5 wt%, 7 wt%, or 10 wt%.

The chemical components of the used furnace materials are shown in the following table 1 in percentage by mass:

TABLE 1 chemical composition of each charge (wt%)

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. the residual stress of the high-wear-resistance high-chromium white cast iron is lower than-180 MPa to-220 MPa and is reduced by 50-60 percent compared with water quenching treatment;

2. the high-wear-resistance high-chromium white cast iron has high hardness which can reach 63-65 HRC;

3. the high-wear-resistance high-chromium white cast iron has high impact toughness which can reach 13.5-15.5J/cm²；

4. The impact abrasive material of the high-wear-resistance high-chromium white cast iron has excellent wear resistance, and is improved by 35-45% compared with Cr15 high-chromium cast iron.

Detailed Description

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto. The raw materials related to the invention can be directly purchased from the market. For process parameters not specifically noted, reference may be made to conventional techniques.

In the preparation steps of the following examples, the percentages are all by mass.

Example 1

The boron white cast iron is smelted by adopting 1000 kg of medium-frequency induction furnace, and the manufacturing process comprises the following steps:

(1) mixing 40.8% of scrap steel, 8.3% of ferrochrome, 1.3% of ferromanganese, 1.5% of ferrotitanium and 47.5% of pure iron, filling the mixture into a smelting furnace, and heating the mixture until the mixture is molten;

(2) crushing ferroboron into blocks with the particle size of less than 20mm, drying at 200 ℃, placing at the bottom of a casting ladle, and adding 0.3% ferroboron blocks into a smelting furnace by adopting a ladle-in-ladle flushing method;

(3) heating the smelting furnace to 1550 ℃, adding a deoxidizer aluminum wire, and adding a 0.3% pure nickel rod after the furnace burden is completely melted;

(4) when the temperature of the molten steel reaches 1400 ℃, casting into a casting, then preserving the heat of the casting at 1000 ℃ for 3h for quenching treatment, putting a PAG solution with the concentration of 3 wt% for cooling to 150 ℃, then preserving the heat at 300 ℃ for 5h for tempering treatment, and cooling to room temperature in air to obtain the white cast iron.

The specific components of the high-strength, high-toughness and high-wear-resistance boron-containing white cast iron prepared by the embodiment are shown in Table 2, the residual stress of the high-wear-resistance high-chromium white cast iron is-180 MPa, and the macro hardness can reach 63 HRC; the impact toughness is high and can reach 15.5J/cm²(ii) a The abrasion performance of the impact abrasive is excellent, and is improved by 38.0% compared with Cr15 high-chromium cast iron.

Example 2

The boron white cast iron is smelted by adopting 1000 kg of medium-frequency induction furnace, and the manufacturing process comprises the following steps:

(1) mixing 42.8% of scrap steel, 8.6% of ferrochrome, 1.4% of ferromanganese, 1.4% of ferrotitanium and 45.2% of pure iron, filling the mixture into a smelting furnace, and heating the mixture until the mixture is molten;

(2) crushing ferroboron into blocks with the particle size of less than 20mm, drying at 200 ℃, placing at the bottom of a casting ladle, and adding 0.3% ferroboron blocks into a smelting furnace by adopting a ladle-in-ladle flushing method;

(3) heating the smelting furnace to 1550 ℃, adding a deoxidizer aluminum wire, and adding a 0.3% pure nickel rod after the furnace burden is completely melted;

(4) when the temperature of the molten steel reaches 1400 ℃, casting into a casting, then preserving the heat of the casting at 1000 ℃ for 3h for quenching treatment, putting a PAG solution with the concentration of 8 wt% for cooling to 150 ℃, then preserving the heat at 300 ℃ for 5h for tempering treatment, and cooling to room temperature in air to obtain the white cast iron.

The specific components of the high-strength, high-toughness and high-wear-resistance boron-containing white cast iron prepared by the embodiment are shown in Table 2, the residual stress of the high-wear-resistance and high-chromium white cast iron is-200 MPa, and the macro hardness can reach 63.5 HRC; the impact toughness is high and can reach 14.5J/cm²(ii) a The abrasion performance of the impact abrasive is excellent and is improved by 42.0 percent compared with Cr15 high-chromium cast iron.

Example 3

The boron white cast iron is smelted by adopting 1000 kg of medium-frequency induction furnace, and the manufacturing process comprises the following steps:

(1) mixing 43.8% of scrap steel, 8.8% of ferrochrome, 1.5% of ferromanganese, 1.5% of ferrotitanium and 43.8% of pure iron, filling the mixture into a smelting furnace, and heating the mixture until the mixture is molten;

(2) crushing ferroboron into blocks with the particle size of less than 20mm, drying at 200 ℃, placing at the bottom of a casting ladle, and adding 0.3% ferroboron blocks into a smelting furnace by adopting a ladle-in-ladle flushing method;

(3) heating the smelting furnace to 1550 ℃, adding a deoxidizer aluminum wire, and adding a 0.3% pure nickel rod after the furnace burden is completely melted;

(4) when the temperature of the molten steel reaches 1400 ℃, casting into a casting, then preserving the heat of the casting at 1000 ℃ for 3h for quenching treatment, putting a PAG solution with the concentration of 10 wt% for cooling to 150 ℃, then preserving the heat at 300 ℃ for 5h for tempering treatment, and cooling to room temperature in air to obtain the white cast iron.

The specific components of the high-strength, high-toughness and high-wear-resistance boron-containing white cast iron prepared by the embodiment are shown in Table 2, the residual stress of the high-wear-resistance and high-chromium white cast iron is-220 MPa, and the macro hardness can reach 65.0 HRC; the impact toughness is high and can reach 13.5J/cm²(ii) a The abrasion performance of the impact abrasive is excellent and is improved by 45 percent compared with Cr15 high-chromium cast iron.

TABLE 2 chemical composition of white cast iron (mass fraction, wt%)

The high-wear-resistance high-chromium white cast iron prepared in the embodiments 1 to 3 has a structure composed of carbides and a martensite matrix, wherein the martensite matrix plays a role in supporting and fixing hard phase carbides, and in turn, the carbides play a role in protecting a matrix from being worn. The high-wear-resistance boron-containing high-chromium white cast iron is formed by smelting in a medium-frequency induction furnace, and is quenched and tempered, and the generated martensite is needle-shaped, has high hardness, high toughness and high wear resistance, and has low residual stress. Chromium is mainly dissolved in carbide in a solid solution mode, carbon is dissolved in the carbide in a solid solution mode and can also be dissolved in a matrix in a solid solution mode, boron is added into a casting, the existence of the boron has certain improvement on hardenability of the casting, the boron has high chemical activity, and in addition to the solid solution in iron, secondary precipitated phase M can be promoted₂₃(B,C)₆Separating out; the boron element has extremely low solid concentration in gamma-Fe and alpha-Fe and is often gathered on the grain boundary to form boride Fe₂Form B exists, which has a high hardness, thereby increasing the progressive overall hardness. The hardness and toughness of the casting are greatly improved, the material has the characteristics of high strength, impact toughness and the like, the service life of the wear-resistant part can be obviously prolonged, and the application prospect is good.

Example 4

Referring to the procedure of example 1, PAG solutions were changed to 1%, 5%, 7%, 10%, and 13% by mass, respectively, and after preparing high-chromium white cast irons, the residual stress, the macro-hardness, and the impact toughness were measured, respectively, with tap water as a control, and the results are shown in tables 3 to 5.

TABLE 3 residual stress values (MPa) of high-chromium white cast iron in different quench solutions

1％PAG	3％PAG	5％PAG	7％PAG	10％PAG	13％PAG	Tap water
							-165.39	-180.00	-190.42	-207.69	-220.00	-253.36	-455.88

TABLE 4 Macro hardness values (HRC) of high-chromium white cast irons in different quench solutions

1％PAG	3％PAG	5％PAG	7％PAG	10％PAG	13％PAG	Tap water
							57.69	63.00	62.78	63.7	65.0	64.85	64.10

TABLE 5 impact toughness (J/cm) of high-chromium white cast iron in different quench solutions²)

1％PAG	3％PAG	5％PAG	7％PAG	10％PAG	13％PAG	Tap water
							14.13	15.5	13.36	13.56	13.5	10.29	8.78

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.