阅读说明：本技术 一种复合稀土增强粉末冶金高速钢的制备方法 (Preparation method of composite rare earth reinforced powder metallurgy high-speed steel ) 是由 欧阳春 高平平 伍小波 吴安如 于 2021-06-17 设计创作，主要内容包括：本发明公开了一种复合稀土增强粉末冶金高速钢及其制备方法,稀土元素的添加在高速钢中有良好的净化与细化晶粒的作用,稀土在晶界和奥氏体的富集可以有效地改善晶界,减少碳化物的偏析,降低其热稳定性使其加热易于溶解,从而产生较好的固溶强化效果,大大增加了高速钢的强度。利用粉末冶金方法在高速钢中引入稀土元素,粉末冶金高速钢本身解决了一次碳化物粗大和偏析的问题,加入适量稀土元素后可以进一步细化晶粒,减少夹杂,使烧结后的孔隙减少。整个技术方案流程简单,操作方便,技术可控,投入小,可满足工业生产需求。(The invention discloses a composite rare earth reinforced powder metallurgy high-speed steel and a preparation method thereof, wherein the addition of rare earth elements has good effects of purifying and refining grains in the high-speed steel, and the enrichment of rare earth in grain boundaries and austenite can effectively improve the grain boundaries, reduce the segregation of carbides, reduce the thermal stability and enable the carbides to be easily dissolved by heating, thereby generating better solid solution strengthening effect and greatly increasing the strength of the high-speed steel. The rare earth elements are introduced into the high-speed steel by using a powder metallurgy method, the problems of coarseness and segregation of primary carbides are solved by the powder metallurgy high-speed steel, and after a proper amount of rare earth elements are added, crystal grains can be further refined, inclusion is reduced, and pores after sintering are reduced. The whole technical scheme has the advantages of simple flow, convenient operation, controllable technology and small investment, and can meet the requirements of industrial production.)

1. A preparation method of composite rare earth reinforced powder metallurgy high-speed steel is characterized by comprising the following steps:

on the basis of powder metallurgy, composite rare earth elements are added into the high-speed steel raw material to obtain the composite rare earth reinforced powder metallurgy high-speed steel.

2. The method for preparing the composite rare earth reinforced powder metallurgy high-speed steel according to claim 1, wherein the method comprises the following steps: the raw materials are Si, Mn, Cr, Mo, W and Fe; the composite rare earth elements are two or more of rare earth elements such as Ce, Y, La, Nd and the like.

3. The method for preparing the composite rare earth reinforced powder metallurgy high-speed steel according to claim 2, wherein the method comprises the following steps: the raw materials and the composite rare earth elements comprise the following components in percentage by mass: si less than 0.5%, Mn less than 0.5%, Cr: 4-8%, Mo: 3-6%, W: 7-12%, RE: 0.1-0.3%, and the balance Fe.

4. Preparation of the composite rare earth reinforced powder metallurgy high speed steel according to claim 2 or 3, wherein: the raw materials and the composite rare earth elements comprise the following components in percentage by mass: si: 0.25%, Mn: 0.30%, Cr: 4-5%, Mo: 3-4%, W: 8-10%, RE: 0.25 percent and the balance of Fe.

5. The method for preparing the composite rare earth reinforced powder metallurgy high-speed steel according to claim 1, wherein the method comprises the following steps: the method comprises the following steps:

the preparation method comprises the following steps of obtaining raw materials with corresponding mass fractions according to a formula, uniformly mixing the raw materials with composite rare earth element powder, adding a forming agent and carbon black, performing ball milling, drying, performing die pressing to obtain a pressed blank, performing vacuum sintering on the pressed blank, and performing sintering cooling to obtain a sintered blank;

under a protective atmosphere, preheating and insulating the obtained sintered blank, then carrying out hot processing, controlling pass deformation and compression ratio, carrying out annealing treatment after thermal deformation is finished, and cooling to room temperature along with a furnace to obtain a sample after hot processing;

preheating the hot-processed sample, carrying out solid solution treatment, rapidly cooling the solid solution treatment to obtain a solid solution state sample, carrying out cryogenic treatment, carrying out isothermal aging treatment after the temperature is raised to room temperature, and cooling the treated sample to obtain a finished product.

6. The method for preparing the composite rare earth reinforced powder metallurgy high-speed steel according to claim 5, wherein the method comprises the following steps: the forming agent is one of polyethylene, stearic acid or paraffin, and the addition amount is 8-15 wt%; the addition amount of the carbon black is 1-2 wt%.

7. The method for preparing the composite rare earth reinforced powder metallurgy high-speed steel according to claim 5, wherein the method comprises the following steps:

the ball milling is wet ball milling, and powder is mixed by adopting a planetary ball mill, wherein the wet milling medium is absolute ethyl alcohol, the protective atmosphere is argon, and the ball-material ratio is 4-5: 1, ball milling at the rotating speed of 180-200 r/min for 40-50 h, drying in vacuum at 68-75 ℃ and sieving to obtain a material to be pressed;

the die pressing is bidirectional die pressing, wherein the die pressing pressure is 140-160 Mpa;

and (3) vacuum sintering, wherein the temperature is 1300-1500 ℃, and the sintering time is 2-3 h.

8. The method for preparing the composite rare earth reinforced powder metallurgy high-speed steel according to claim 5, wherein the method comprises the following steps:

carrying out hot processing after preheating and heat preservation, wherein the preheating temperature is 1150-1200 ℃, the heat preservation time is 30min, and the protective atmosphere is generator gas;

the hot working is any one of hot forging, rolling and rotary forging;

the heat deformation is carried out, wherein the pass deformation is 5%, and the compression ratio is 70%;

and annealing, wherein the annealing temperature is 800-870 ℃, and the annealing time is 2-3 h.

9. The method for preparing the composite rare earth reinforced powder metallurgy high-speed steel according to claim 5, wherein the method comprises the following steps: the sample after the hot processing is preheated in a box-type resistance furnace preheating mode, wherein the preheating temperature is 220-280 ℃, and the preheating time is 15-20 min.

10. The method for preparing the composite rare earth reinforced powder metallurgy high-speed steel according to claim 5, wherein the method comprises the following steps:

the solid solution treatment is carried out in a salt bath solid solution mode, the solid solution temperature is 1150-1200 ℃, the solid solution time is 15-30 min, and the cooling mode after solid solution is oil cooling;

the deep cooling treatment is carried out in a deep cooling box deep cooling mode, wherein the deep cooling temperature is-100 to-80 ℃, and the deep cooling time is 2 to 4 hours;

the aging treatment is carried out in a resistance furnace treatment mode, the aging temperature is 550-680 ℃, the treatment times are 2 times, and the aging heat preservation time is 2.5 hours.

Technical Field

The invention relates to the field of metal material manufacturing, in particular to powder metallurgy high-speed steel for realizing strong hardening through intermetallic compounds and carbonitride.

Background

High speed tool steels have been known as tool materials for nearly a hundred years. Due to the characteristics of high hardness, high wear resistance and the like, the wear-resistant steel has very important significance in the processing field. High speed steel is often used to make cutting devices such as taps, dies, drills, cutters, and the like. The excellent cutting performance of the high-speed steel is mainly derived from the result that the martensite matrix strengthening and the carbide secondary hardening are balanced. From the chemical composition point of view, high speed steel is a high performance tool steel containing a large amount of strong carbide forming elements (C, W, Mo). The types of hard carbides mainly include: MC (2100-2800HV), M₂C(1800-2250HV)、M₆C (1800) -2250HV) and M₇C₃(1890-2060 HV). MC is taken as an eutectic phase and can be dispersed and distributed in a martensite matrix in a granular mode, and other types of carbides are eutectic reaction products which are distributed in a network mode and then are in a solidified interdendritic region. The coarse meshed primary carbide is difficult to eliminate in the subsequent forging and heat treatment processes, stress concentration is easily caused, cracks are generated in the machining process, and the service life of the high-speed steel is seriously influenced. In order to obtain dispersed hard carbide (especially high hardness MC phase), it has been studied to promote the network metastable phase M by heat treatment or adding a small amount of alloy elements₂C is decomposed into dispersed MC at high temperature, so that the cost is increased due to the increase of the processing procedure, and meanwhile, the anisotropy of the material is damaged by band-shaped carbide caused by hot processing, so that the mechanical property of the high-speed steel cutter is limited in the using process.

Meanwhile, the application of the powder metallurgy technology in the high-speed steel can effectively refine the structure, and the high-speed steel with uniformly distributed carbide and uniform structure is obtained. Compared with the traditional casting high-speed steel, the powder metallurgy high-speed steel has better mechanical property. However, the material treated by the powder metallurgy processing technology still has the problem of segregation of harmful elements in the alloy, so that the mechanical property of the material is influenced.

Disclosure of Invention

This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.

The present invention has been made in view of the current situation of the high-speed steel.

Therefore, one of the objects of the present invention is to further improve the hardness and wear resistance of high speed steel. Through the addition of the composite rare earth elements, the structure of the alloy is more uniform, the characteristic that the rare earth elements can adsorb harmful elements is utilized, the segregation of the harmful elements in the alloy structure is reduced, and the effect of purifying molten steel is achieved. Because the alloy structure is more uniform, the hardness and the wear resistance of the material are obviously improved.

In order to solve the technical problems, the invention provides the following technical scheme: the composite rare earth reinforced powder metallurgy high-speed steel and the preparation method thereof are characterized in that:

on the basis of powder metallurgy, composite rare earth elements are added into the high-speed steel raw material to obtain the composite rare earth reinforced powder metallurgy high-speed steel.

As a preferred scheme of the preparation method of the composite rare earth reinforced powder metallurgy high-speed steel, the preparation method comprises the following steps: the raw materials are Si, Mn, Cr, Mo, W and Fe; the composite rare earth elements are two or more of rare earth elements such as Ce, Y, La, Nd and the like.

As a preferred scheme of the preparation method of the composite rare earth reinforced powder metallurgy high-speed steel, the preparation method comprises the following steps: the raw materials and the composite rare earth elements comprise the following components in percentage by mass: si less than 0.5%, Mn less than 0.5%, Cr: 4-8%, Mo: 3-6%, W: 7-12%, RE: 0.1-0.3%, and the balance Fe.

As a preferred scheme of the preparation method of the composite rare earth reinforced powder metallurgy high-speed steel, the preparation method comprises the following steps: the raw materials and the composite rare earth elements comprise the following components in percentage by mass: si: 0.25%, Mn: 0.30%, Cr: 4-5%, Mo: 3-4%, W: 8-10%, RE: 0.25 percent and the balance of Fe.

As a preferred scheme of the preparation method of the composite rare earth reinforced powder metallurgy high-speed steel, the preparation method comprises the following steps:

the preparation method comprises the following steps of obtaining raw materials with corresponding mass fractions according to a formula, uniformly mixing the raw materials with composite rare earth element powder, adding a forming agent and carbon black, performing ball milling, drying, performing die pressing to obtain a pressed blank, performing vacuum sintering on the pressed blank, and performing sintering cooling to obtain a sintered blank;

under a protective atmosphere, preheating and insulating the obtained sintered blank, then carrying out hot processing, controlling pass deformation and compression ratio, carrying out annealing treatment after thermal deformation is finished, and cooling to room temperature along with a furnace to obtain a sample after hot processing;

preheating the hot-processed sample, carrying out solid solution treatment, rapidly cooling the solid solution treatment to obtain a solid solution state sample, carrying out cryogenic treatment, and carrying out isothermal aging treatment after the temperature is raised to room temperature to obtain a finished product.

As a preferred scheme of the preparation method of the composite rare earth reinforced powder metallurgy high-speed steel, the preparation method comprises the following steps: the forming agent is one of polyethylene, stearic acid or paraffin, and the addition amount is 8-15 wt%; the addition amount of the carbon black is 1-2 wt%;

as a preferred scheme of the preparation method of the composite rare earth reinforced powder metallurgy high-speed steel, the preparation method comprises the following steps:

the ball milling is wet ball milling, and powder is mixed by adopting a planetary ball mill, wherein the wet milling medium is absolute ethyl alcohol, the protective atmosphere is argon, and the ball-material ratio is 4-5: 1, ball milling at the rotating speed of 180-200 r/min for 40-50 h, drying in vacuum at 68-75 ℃ and sieving to obtain a material to be pressed;

the die pressing is bidirectional die pressing, wherein the die pressing pressure is 140-160 Mpa;

and (3) vacuum sintering, wherein the temperature is 1300-1500 ℃, and the sintering time is 2-3 h.

As a preferred scheme of the preparation method of the composite rare earth reinforced powder metallurgy high-speed steel, the preparation method comprises the following steps:

carrying out hot processing after preheating and heat preservation, wherein the preheating temperature is 1150-1200 ℃, the heat preservation time is 30min, and the protective atmosphere is generator gas;

the hot working is any one of hot forging, rolling and rotary forging;

the heat deformation is carried out, wherein the pass deformation is 5%, and the compression ratio is 70%;

and annealing, wherein the annealing temperature is 800-870 ℃, and the annealing time is 2-3 h.

As a preferred scheme of the preparation method of the composite rare earth reinforced powder metallurgy high-speed steel, the preparation method comprises the following steps: preheating the sample after the hot processing in a box-type resistance furnace at 220-280 ℃ for 15-20 min;

as a preferred scheme of the preparation method of the composite rare earth reinforced powder metallurgy high-speed steel, the preparation method comprises the following steps:

the solid solution treatment is carried out in a salt bath solid solution mode, the solid solution temperature is 1150-1200 ℃, the solid solution time is 15-30 min, and the cooling mode after solid solution is oil cooling;

the deep cooling treatment is carried out in a deep cooling box deep cooling mode, wherein the deep cooling temperature is-100 to-80 ℃, and the deep cooling time is 2 to 4 hours;

the aging treatment is carried out in a resistance furnace treatment mode, the aging temperature is 550-680 ℃, the treatment times are 2 times, and the aging heat preservation time is 2.5 hours. The invention has the beneficial effects that:

the composite rare earth reinforced powder metallurgy high-speed steel prepared by the scheme of the invention has the advantages that the crystal grains of the alloy in the finished product are obviously refined, the form of the carbide is changed from continuous net without modification treatment into intermittent net and particle, the unevenness of eutectic carbide in the alloy is improved, the total amount of non-metallic inclusions in the alloy is generally reduced, and the size of the inclusions is reduced. Has excellent mechanical property and excellent wear resistance, and has high hardness (70-85 HRA), high bending strength (2800-3300 MPa) and impact toughness (8.1-9.8J/cm)²)。

The added composite rare earth elements have good purification and grain refinement effects in high-speed steel, and can generate good purification effect and desulfurization, dephosphorization and deoxidation effects. The enrichment of rare earth elements in the grain boundary and austenite can effectively improve the grain boundary, reduce the segregation of carbide, reduce the thermal stability of carbide and ensure that the carbide is easy to dissolve when being heated, thereby producing better solid solution strengthening effect and greatly increasing the strength of high-speed steel. Compared with the rare earth element, the addition of the composite rare earth can ensure that the high-speed steel has better hardness, bending strength, impact toughness and less abrasion loss, thereby achieving better use effect.

The invention introduces the composite rare earth into the high-speed steel by using a powder metallurgy method, the powder metallurgy high-speed steel solves the problems of coarseness and segregation of primary carbides, and after a proper amount of composite rare earth elements are added, crystal grains can be further refined, inclusions are reduced, and pores after sintering are reduced. And when the Ce: y: la: when Nd is 1:1:0.5:0.5, the high-speed steel obtained has the best performance.

The whole technical scheme has the advantages of simple flow, convenient operation, controllable technology and small investment, and can meet the requirements of industrial production.

Detailed Description

The technical solution of the present invention is further illustrated by the following specific examples.

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, specific embodiments thereof are described in detail below with reference to examples of the specification.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.

Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.

The starting powders used in the present invention are commercially high purity (> 99.8%) and ultrafine (average particle size < 5 μm) powders.

The method for testing the performance of the high-speed steel comprises the following steps: testing the hardness of the alloy by an HRA Rockwell hardness tester; testing the bending strength of the steel by a three-point bending loading method; testing the impact performance of the 500J pendulum impact tester controlled by a computer; the loss of the alloy is measured after the alloy is abraded for a certain time.

Example 1

The weight percentages are as follows: si: 0.25%, Mn: 0.30%, Cr: 4%, Mo: 3%, W: 8%, RE: 0.25% (Ce: Y ═ 1:1), and the balance Fe, and the powder was prepared. Mixing the prepared raw material powder, 9 wt% of forming agent paraffin and 1.8 wt% of carbon black, and placing the mixture into a ball milling tank of a planetary ball mill for wet ball milling, wherein the ball milling medium is absolute ethyl alcohol, the protective gas is argon, the ball-material ratio is 5:1, the rotating speed is 200r/min, and the ball milling time is 40 h. And after the ball milling is finished, drying in a vacuum drying oven at 75 ℃, drying, sieving and granulating, and performing bidirectional die pressing on the mixed powder under the pressure of 160MPa to obtain a pressed compact. And (3) placing the pressed blank in a vacuum sintering furnace for sintering, wherein the final sintering temperature is 1350 ℃, the temperature is kept for 2 hours at the highest temperature stage, and the pressed blank is cooled along with the furnace to obtain a sintered blank. Preheating the sintered blank in a box furnace under the protection of nitrogen at 1150 ℃, carrying out free forging after the temperature is kept for 30min, achieving a compression ratio of 70% after three passes of thermal processing, and cooling to obtain a thermally processed sample. Annealing the hot processed sample in a box furnace at 870 ℃ for 2 hours, cooling, performing solid solution treatment in a salt bath at the solid solution temperature of 1200 ℃, keeping the temperature for 30min, cooling to room temperature through oil cooling, and performing cryogenic treatment in a liquid nitrogen cryogenic box for 3 hours at the cryogenic treatment temperature of-80 ℃. After the temperature of the sample is returned to the room temperature, isothermal aging treatment is carried out in a box furnace at 550 ℃, the heat preservation time is 2.5 hours, and the required composite rare earth reinforced powder metallurgy high-speed steel is obtained after cooling, wherein the specific properties are shown in table 1.

Example 2

The weight percentages are as follows: si: 0.25%, Mn: 0.30%, Cr: 5%, Mo: 4%, W: 10%, RE: 0.25% (Ce: Y ═ 1:1), and the balance Fe, and the powder was prepared. Mixing the prepared raw material powder, 9 wt% of forming agent paraffin and 1.8 wt% of carbon black, and placing the mixture into a ball milling tank of a planetary ball mill for wet ball milling, wherein the ball milling medium is absolute ethyl alcohol, the protective gas is argon, the ball-material ratio is 5:1, the rotating speed is 200r/min, and the ball milling time is 40 h. And after the ball milling is finished, drying in a vacuum drying oven at 75 ℃, drying, sieving and granulating, and performing bidirectional die pressing on the mixed powder under the pressure of 160MPa to obtain a pressed compact. And (3) placing the pressed blank in a vacuum sintering furnace for sintering, wherein the final sintering temperature is 1350 ℃, the temperature is kept for 2 hours at the highest temperature stage, and the pressed blank is cooled along with the furnace to obtain a sintered blank. Preheating the sintered blank in a box furnace under the protection of nitrogen at 1150 ℃, carrying out free forging after the temperature is kept for 30min, achieving a compression ratio of 70% after three passes of thermal processing, and cooling to obtain a thermally processed sample. Annealing the hot processed sample in a box furnace at 870 ℃ for 2 hours, cooling, performing solid solution treatment in a salt bath at the solid solution temperature of 1200 ℃, keeping the temperature for 30min, cooling to room temperature through oil cooling, and performing cryogenic treatment in a liquid nitrogen cryogenic box for 3 hours at the cryogenic treatment temperature of-80 ℃. After the temperature of the sample is returned to the room temperature, isothermal aging treatment is carried out in a box furnace at 550 ℃, the heat preservation time is 2.5 hours, and the required composite rare earth reinforced powder metallurgy high-speed steel is obtained after cooling, wherein the specific properties are shown in table 1.

Example 3

The weight percentages are as follows: si: 0.25%, Mn: 0.30%, Cr: 6%, Mo: 4%, W: 10%, RE: 0.25% (Ce: Y ═ 1:1), and the balance Fe, and the powder was prepared. Mixing the prepared raw material powder, 9 wt% of forming agent paraffin and 1.8 wt% of carbon black, and placing the mixture into a ball milling tank of a planetary ball mill for wet ball milling, wherein the ball milling medium is absolute ethyl alcohol, the protective gas is argon, the ball-material ratio is 5:1, the rotating speed is 200r/min, and the ball milling time is 45 hours. And after the ball milling is finished, drying in a vacuum drying oven at 70 ℃, drying, sieving and granulating, and performing bidirectional die pressing on the mixed powder under the pressure of 150MPa to obtain a pressed compact. And (3) placing the pressed compact into a vacuum sintering furnace for sintering, wherein the final sintering temperature is 1400 ℃, the temperature is kept for 2 hours at the highest temperature stage, and the pressed compact is cooled along with the furnace to obtain a sintered compact. Preheating the sintered blank in a box furnace under the protection of nitrogen at 1150 ℃, carrying out free forging after heat preservation for 30min, achieving a compression ratio of 70% after three passes of thermal processing, and cooling to obtain a sample after thermal processing. Annealing the hot processed sample in a box type furnace at 840 ℃ for 2 hours, cooling, then carrying out solid solution treatment in a salt bath, wherein the solid solution temperature is 1200 ℃, keeping the temperature for 15min, then cooling to room temperature through oil cooling, and then carrying out cryogenic treatment in a liquid nitrogen cryogenic box for 3 hours, wherein the cryogenic treatment temperature is-80 ℃. After the temperature of the sample is returned to the room temperature, isothermal aging treatment is carried out in a box-type furnace at the temperature of 600 ℃, the heat preservation time is 2.5 hours, and the required composite rare earth reinforced powder metallurgy high-speed steel is obtained after cooling, wherein the specific properties are shown in table 1.

Example 4

The weight percentages are as follows: si: 0.25%, Mn: 0.30%, Cr: 7%, Mo: 5%, W: 7%, RE: 0.3% (Ce: Y ═ 1:1), and the balance Fe, and the powder was prepared. Mixing the prepared raw material powder, 10 wt% of forming agent paraffin and 1.5 wt% of carbon black, and placing the mixture into a ball milling tank of a planetary ball mill for wet ball milling, wherein the ball milling medium is absolute ethyl alcohol, the protective gas is argon, the ball-material ratio is 4:1, the rotating speed is 180r/min, and the ball milling time is 50 h. And after the ball milling is finished, drying in a vacuum drying box at 68 ℃, drying, sieving and granulating, and performing bidirectional die pressing on the mixed powder under the pressure of 140MPa to obtain a pressed compact. And (3) placing the pressed blank in a vacuum sintering furnace for sintering, wherein the final sintering temperature is 1500 ℃, the temperature is kept for 2 hours at the highest temperature stage, and the pressed blank is cooled along with the furnace to obtain a sintered blank. Preheating the sintered blank in a box furnace under the protection of nitrogen at 1200 ℃, carrying out free forging after the temperature is kept for 30min, achieving a compression ratio of 70% after three passes of thermal processing, and cooling to obtain a thermally processed sample. Annealing the hot processed sample in a box furnace at 800 ℃ for 3 hours, cooling, performing solid solution treatment in a salt bath at the solid solution temperature of 1150 ℃, preserving heat for 30min, cooling to room temperature through oil cooling, and performing cryogenic treatment in a liquid nitrogen cryogenic box for 3 hours at the cryogenic treatment temperature of-90 ℃. After the temperature of the sample is returned to the room temperature, isothermal aging treatment is carried out in a box furnace at the temperature of 630 ℃, the heat preservation time is 2.5 hours, and the required composite rare earth reinforced powder metallurgy high-speed steel is obtained after cooling, wherein the specific properties are shown in table 1.

Example 5

The weight percentages are as follows: si: 0.25%, Mn: 0.30%, Cr: 8%, Mo: 6%, W: 12%, RE: 0.3% (Ce: Y: 3:5), and the balance Fe, and taking the powder. Mixing the prepared raw material powder, 15 wt% of forming agent paraffin and 2 wt% of carbon black, and placing the mixture into a ball milling tank of a planetary ball mill for wet ball milling, wherein the ball milling medium is absolute ethyl alcohol, the protective gas is argon gas, the ball-material ratio is 4:1, the rotating speed is 180r/min, and the ball milling time is 50 h. And after the ball milling is finished, drying in a vacuum drying box at 68 ℃, drying, sieving and granulating, and performing bidirectional die pressing on the mixed powder under the pressure of 140MPa to obtain a pressed compact. And (3) placing the pressed blank into a vacuum sintering furnace for sintering, wherein the final sintering temperature is 1300 ℃, the temperature is kept for 3 hours at the highest temperature stage, and the pressed blank is cooled along with the furnace to obtain a sintered blank. Preheating the sintered blank in a box furnace under the protection of nitrogen at 1200 ℃, carrying out free forging after the temperature is kept for 30min, achieving a compression ratio of 70% after three passes of thermal processing, and cooling to obtain a thermally processed sample. Annealing the hot processed sample in a box furnace at 800 ℃ for 3 hours, cooling, performing solid solution treatment in a salt bath at the solid solution temperature of 1150 ℃, preserving heat for 30min, cooling to room temperature through oil cooling, and performing cryogenic treatment in a liquid nitrogen cryogenic box for 2 hours at the cryogenic treatment temperature of-100 ℃. After the temperature of the sample is returned to the room temperature, isothermal aging treatment is carried out in a box-type furnace at 680 ℃, the heat preservation time is 2.5 hours, and the required composite rare earth reinforced powder metallurgy high-speed steel is obtained after cooling, wherein the specific properties are shown in table 1.

Example 6

The weight percentages are as follows: si: 0.25%, Mn: 0.30%, Cr: 4%, Mo: 3%, W: 8%, RE: 0.25% (Ce: Y: La: Nd ═ 1:1:0.25:0.5), and the balance Fe, and the powder was prepared. Mixing the prepared raw material powder, 9 wt% of forming agent paraffin and 1.8 wt% of carbon black, and placing the mixture into a ball milling tank of a planetary ball mill for wet ball milling, wherein the ball milling medium is absolute ethyl alcohol, the protective gas is argon, the ball-material ratio is 5:1, the rotating speed is 200r/min, and the ball milling time is 40 h. And after the ball milling is finished, drying in a vacuum drying oven at 75 ℃, drying, sieving and granulating, and performing bidirectional die pressing on the mixed powder under the pressure of 160MPa to obtain a pressed compact. And (3) placing the pressed blank in a vacuum sintering furnace for sintering, wherein the final sintering temperature is 1350 ℃, the temperature is kept for 2 hours at the highest temperature stage, and the pressed blank is cooled along with the furnace to obtain a sintered blank. Preheating the sintered blank in a box furnace under the protection of nitrogen at 1150 ℃, carrying out free forging after the temperature is kept for 30min, achieving a compression ratio of 70% after three passes of thermal processing, and cooling to obtain a thermally processed sample. Annealing the hot processed sample in a box furnace at 870 ℃ for 2 hours, cooling, performing solid solution treatment in a salt bath at the solid solution temperature of 1200 ℃, keeping the temperature for 30min, cooling to room temperature through oil cooling, and performing cryogenic treatment in a liquid nitrogen cryogenic box for 3 hours at the cryogenic treatment temperature of-80 ℃. After the temperature of the sample is returned to the room temperature, isothermal aging treatment is carried out in a box furnace at 550 ℃, the heat preservation time is 2.5 hours, and the required composite rare earth reinforced powder metallurgy high-speed steel is obtained after cooling, wherein the specific properties are shown in table 2.

Example 7

The weight percentages are as follows: si: 0.25%, Mn: 0.30%, Cr: 4%, Mo: 3%, W: 8%, RE: 0.25% (Ce: Y: La: Nd ═ 1:1:0.5:0.5), and the balance Fe, and the powder was prepared. Mixing the prepared raw material powder, 9 wt% of forming agent paraffin and 1.8 wt% of carbon black, and placing the mixture into a ball milling tank of a planetary ball mill for wet ball milling, wherein the ball milling medium is absolute ethyl alcohol, the protective gas is argon, the ball-material ratio is 5:1, the rotating speed is 200r/min, and the ball milling time is 40 h. And after the ball milling is finished, drying in a vacuum drying oven at 75 ℃, drying, sieving and granulating, and performing bidirectional die pressing on the mixed powder under the pressure of 160MPa to obtain a pressed compact. And (3) placing the pressed blank in a vacuum sintering furnace for sintering, wherein the final sintering temperature is 1350 ℃, the temperature is kept for 2 hours at the highest temperature stage, and the pressed blank is cooled along with the furnace to obtain a sintered blank. Preheating the sintered blank in a box furnace under the protection of nitrogen at 1150 ℃, carrying out free forging after the temperature is kept for 30min, achieving a compression ratio of 70% after three passes of thermal processing, and cooling to obtain a thermally processed sample. Annealing the hot processed sample in a box furnace at 870 ℃ for 2 hours, cooling, performing solid solution treatment in a salt bath at the solid solution temperature of 1200 ℃, keeping the temperature for 30min, cooling to room temperature through oil cooling, and performing cryogenic treatment in a liquid nitrogen cryogenic box for 3 hours at the cryogenic treatment temperature of-80 ℃. After the temperature of the sample is returned to the room temperature, isothermal aging treatment is carried out in a box furnace at 550 ℃, the heat preservation time is 2.5 hours, and the required composite rare earth reinforced powder metallurgy high-speed steel is obtained after cooling, wherein the specific properties are shown in table 2.

Example 8

The weight percentages are as follows: si: 0.25%, Mn: 0.30%, Cr: 4%, Mo: 3%, W: 8%, RE: 0.25% (Ce: Y: La: Nd ═ 1:1:0.75:0.5), and the balance Fe, and the powder was prepared. Mixing the prepared raw material powder, 9 wt% of forming agent paraffin and 1.8 wt% of carbon black, and placing the mixture into a ball milling tank of a planetary ball mill for wet ball milling, wherein the ball milling medium is absolute ethyl alcohol, the protective gas is argon, the ball-material ratio is 5:1, the rotating speed is 200r/min, and the ball milling time is 40 h. And after the ball milling is finished, drying in a vacuum drying oven at 75 ℃, drying, sieving and granulating, and performing bidirectional die pressing on the mixed powder under the pressure of 160MPa to obtain a pressed compact. And (3) placing the pressed blank in a vacuum sintering furnace for sintering, wherein the final sintering temperature is 1350 ℃, the temperature is kept for 2 hours at the highest temperature stage, and the pressed blank is cooled along with the furnace to obtain a sintered blank. Preheating the sintered blank in a box furnace under the protection of nitrogen at 1150 ℃, carrying out free forging after the temperature is kept for 30min, achieving a compression ratio of 70% after three passes of thermal processing, and cooling to obtain a thermally processed sample. Annealing the hot processed sample in a box furnace at 870 ℃ for 2 hours, cooling, performing solid solution treatment in a salt bath at the solid solution temperature of 1200 ℃, keeping the temperature for 30min, cooling to room temperature through oil cooling, and performing cryogenic treatment in a liquid nitrogen cryogenic box for 3 hours at the cryogenic treatment temperature of-80 ℃. After the temperature of the sample is returned to the room temperature, isothermal aging treatment is carried out in a box furnace at 550 ℃, the heat preservation time is 2.5 hours, and the required composite rare earth reinforced powder metallurgy high-speed steel is obtained after cooling, wherein the specific properties are shown in table 2.

Table 1 test results of mechanical properties, abrasion resistance and high-temperature hardness of samples in examples 1 to 5

TABLE 2 test results of mechanical properties, abrasion resistance and high-temperature hardness of samples in examples 6 and 7

As can be seen from tables 1 and 2, the high-speed steel added with the composite rare earth elements Ce, Y, La and Nd has higher hardness and bending strength, stronger impact toughness and less abrasion loss than the high-speed steel added with Ce, Y and two rare earth elements. And when Ce: y: la: when Nd is 1:1:0.5:0.5, the composite rare earth reinforced high speed steel shows the best performance. In general, the high-speed steel added with the four rare earth elements of Ce, Y, La and Nd has better use effect.

In order to solve the above practical problems and improve the quality of high-speed steel, the present invention provides a composite rare earth reinforced powder metallurgy high-speed steel, in which the total amount of non-metallic inclusions in the steel is generally reduced, the size of the inclusions is reduced, the grains of the steel are refined, and the unevenness of eutectic carbide of the steel is improved to strengthen the matrix of the steel.

According to the invention, the performance test is carried out on the composite rare earth reinforced high-speed steel with different proportions, the quality of the high-speed steel is improved, and the added rare earth elements prove that Ce, Y, La and Nd are added, and when Ce: y: la: when Nd is 1:1:0.5:0.5, the crystal grains of the alloy in the finished product are obviously refined, the unevenness of eutectic carbide in the alloy is obviously improved, the total amount of non-metallic inclusions in the alloy is generally reduced, and the size of the inclusions is reduced. The high-speed steel has better hardness, bending strength, impact toughness and abrasion loss, and achieves better use effect.

It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.