阅读说明：本技术 一种金属间化合物与碳氮化物共同强硬化粉末冶金高速钢及其制备方法 (Intermetallic compound and carbonitride jointly-strengthened hardening powder metallurgy high-speed steel and preparation method thereof ) 是由 康希越 袁紫仁 谢丰伟 贺跃辉 于 2019-08-09 设计创作，主要内容包括：本发明公开了一种金属间化合物与碳氮化物共同强硬化粉末冶金高速钢,以原位生成的金属间化合物及外加碳氮化物对钢基体进行强化,通过粉末冶金方法得到金属间化合物与碳化物共同强硬化粉末冶金高速钢。本发明通过特定的稳定碳氮化物及合金元素添加,通过外加碳氮化物及原位生成的金属间化合物对材料进行共同强化,得到一种金属间化合物与碳氮化物共同强硬化粉末冶金高速钢。由于金属间化合物和基体中较少的碳,材料能保持优异的红硬性及抗粘刀性,同时稳定的高硬度碳氮化物的加入能够起到明显的细化晶粒及耐磨性提升的作用。(The invention discloses a intermetallic compound and carbonitride jointly-strengthened powder metallurgy high-speed steel, which is obtained by strengthening a steel matrix by using an intermetallic compound generated in situ and an added carbonitride through a powder metallurgy method. The invention adds specific stable carbonitride and alloy elements, and jointly strengthens the material by adding the carbonitride and intermetallic compounds generated in situ to obtain the intermetallic compound and carbonitride jointly hardened powder metallurgy high-speed steel. Because the intermetallic compound and the matrix contain less carbon, the material can keep excellent red hardness and anti-knife-sticking performance, and meanwhile, the stable high-hardness carbonitride can play the roles of obviously refining grains and improving the wear resistance.)

1. An intermetallic compound and carbonitride jointly strongly hardened powder metallurgy high-speed steel, which is characterized in that: the intermetallic compound and the added carbonitride generated in situ are used for strengthening the steel matrix, and the intermetallic compound and the carbide jointly strengthen and harden the powder metallurgy high-speed steel by a powder metallurgy method.

2. The intermetallic compound and carbonitride co-strongly hardened powder metallurgy high speed steel according to claim 1, characterized in that: the intermetallic compound is mainly generated in situ by metal elements Fe, Co, Ni, Mo, W, Ti and Nb, and the added carbonitride is one or more of TiC, TiN, Ti (C, N), NbC, TaC, TaN, ZrC and ZrN.

3. The intermetallic compound and carbonitride co-hardenable powder metallurgy high speed steel according to claim 1 or 2, characterized in that: the intermetallic compound and carbide jointly-strengthened hard powder metallurgy high-speed steel is prepared from the following components in percentage by mass: co: 10-30%, Mo: 5-25%, W: 2-20% of carbonitride: 1-15% and the balance Fe.

4. The intermetallic compound and carbonitride co-strongly hardened powder metallurgy high speed steel according to claim 3, characterized in that: the intermetallic compound and carbide jointly-strengthened hard powder metallurgy high-speed steel is prepared from the following components in percentage by mass: co: 10-30%, Mo: 8-18%, W: 2-10%, carbonitride: 2-10% and the balance Fe.

5. The method for preparing the intermetallic compound and carbide jointly strongly hardened powder metallurgy high-speed steel according to any one of claims 1 to 4 is characterized by comprising the following specific steps:

1) obtaining raw material powder with corresponding mass fraction according to a formula, adding a forming agent and carbon black, performing ball milling, performing die pressing to obtain a pressed compact, performing vacuum sintering on the pressed compact, and performing sintering cooling to obtain a sintered compact;

2) heating and insulating the sintered blank obtained in the step 1) in an inert atmosphere, then carrying out hot processing, controlling pass deformation and compression ratio, annealing after thermal deformation is finished, and then cooling to room temperature along with the furnace;

3) preheating the sample obtained in the step 2), carrying out solid solution treatment, rapidly cooling the solid solution treatment to obtain a solid solution state sample, then carrying out cryogenic treatment, cooling to room temperature, and carrying out aging treatment to obtain a finished product.

6. The method for producing an intermetallic compound and carbonitride co-strongly hardened powder metallurgy high speed steel according to claim 5, characterized in that: in the step 1), the forming agent is paraffin, the adding amount is 3-6 wt%, and the adding amount of the carbon black is 0.4-0.8 wt%;

the ball milling mode is wet ball milling, the ball milling medium is alcohol, and the ball material ratio is (3-6): 1, planetary ball milling or roller ball milling can be carried out, the rotating speed is 200-280 r/min when planetary ball milling is used, and the ball milling time is 48-60 h; the rotating speed is 80-120 r/min during roller ball milling, and the ball milling time is 72-86 h;

the mould pressing mode is bidirectional or unidirectional mould pressing, and the pressure is 120-180 MPa;

the sintering temperature is 1300-1400 ℃, and the sintering time is 1-3 h.

7. The method for producing an intermetallic compound and carbonitride co-strongly hardened powder metallurgy high speed steel according to claim 5, characterized in that: in the step 2), the heating temperature before hot working is 1120-1180 ℃, the heat preservation time is 20-40 min, and the inert atmosphere is nitrogen atmosphere or argon atmosphere.

The hot working is selected from any one of hot forging, rolling and rotary forging, the pass deformation amount during thermal deformation is less than 5%, and the compression ratio during thermal deformation is 60-80%;

the annealing temperature is 750-900 ℃, and the annealing time is 1-3 h.

8. The method for producing an intermetallic compound and carbonitride co-strongly hardened powder metallurgy high speed steel according to claim 5, characterized in that: in the step 3), preheating is carried out in a box type resistance furnace, wherein the preheating temperature is 200-300 ℃, and the preheating time is 10-30 min;

carrying out solid solution treatment in a salt bath, wherein the solid solution temperature is 1100-1250 ℃, the solid solution time is 15-30 min, and the cooling mode is oil cooling;

the deep cooling is carried out in a deep cooling box, the deep cooling temperature is-100 to-80 ℃, and the deep cooling time is 1 to 3 hours;

the aging treatment is carried out in a resistance furnace, the aging temperature is 500-700 ℃, the aging treatment times are 1-2 times, and the aging heat preservation time is 1-3 hours.

Technical Field

The invention relates to the field of machining tools, in particular to powder metallurgy high-speed steel for realizing strong hardening through intermetallic compounds and carbonitrides.

Background

High-speed steel is successfully developed in the 90 th 19 th century, the requirement on material processing is higher and higher along with the rapid development of industrial technology in more than one hundred years, the traditional cast-forged high-speed steel cannot meet the processing requirement, and the type and preparation mode of the high-speed steel are continuously updated. The titanium alloy, the high-temperature alloy and the stainless steel material are widely applied to various fields and can be used in the industries of aerospace technology, military equipment, biomedicine, ocean engineering, energy and power, automobile manufacturing and the like. However, the materials are difficult to process, due to the difficult processing characteristics of poor heat conductivity, easy cutter sticking and the like, the heat conductivity is poor in the processing process, the temperature of the processed surface can reach more than 600 ℃ due to heat accumulation, and an oxidized hard layer (with the thickness of 0.1-0.15 mm) is formed on the processed surface. In the past, for processing materials such as titanium alloy, high-temperature alloy, stainless steel and the like, the selected conventional carbide high-speed steel and hard alloy have self defects, the hardness of a cutter is sharply reduced at high temperature of the carbide high-speed steel, the carbide is gathered, the cutter is severely worn, and the cutting edge is cracked; the hard alloy has poor toughness, is easy to stick a cutter to form a cutter edge, and takes away a coating to cause the cutter material to lose efficacy.

Therefore, the intermetallic compound high-speed hardened steel has high red hardness and excellent tempering resistance compared with carbide high-speed steel, has good strength, toughness and thermal conductivity compared with hard alloy, and can better make up the application blank between the intermetallic compound high-speed hardened steel and the carbide high-speed steel. The initial research of the method starts from the 30 th century, is mainly carried out in Germany, Soviet Union, Japan and other countries, adopts the casting and forging method for preparation, has the defect of poor toughness, and later adopts the same gas atomization-hot isostatic pressing process as the conventional high-speed steel along with the upgrade of the preparation technology. The material is a novel aging high-speed steel material, and intermetallic compounds which are dispersed and distributed in situ in sintering are generated by adding alloy elements such as Co, Ni, Mo, W and the like into the steel, so that the effect of strengthening and hardening is realized. Compared with carbide, the intermetallic compound has higher anti-aggregation capability and thermal stability, and simultaneously has high hardness and higher strength due to the good interface relationship between the intermetallic compound phase precipitated in situ and the matrix, and the thermal conductivity is about twice of that of high-speed steel and hard alloy. The intermetallic compound high-hardness high-speed steel has the characteristics of good red hardness, high strength and toughness, large heat conductivity coefficient and excellent anti-sticking property, and is considered to be more suitable for processing materials such as titanium alloy, high-temperature alloy, stainless steel and the like.

However, in the traditional powder metallurgy preparation of intermetallic compound high-hardening high-speed steel, because no carbide hinders the grain growth, the defects of overlarge grain after sintering and the like still exist, meanwhile, the microhardness of the intermetallic compound is 1400HV and is still lower than most carbides, and the hardness and the wear resistance at lower temperature are still lower than those of the traditional carbide high-hardening high-speed steel.

Disclosure of Invention

The invention aims to further improve the hardness and the wear resistance of intermetallic compound high-hardening high-speed steel aiming at the current difficult-to-process situation of materials such as titanium alloy, high-temperature alloy, stainless steel and the like. The material is jointly strengthened by adding specific stable carbonitride and alloy elements, and by adding the carbonitride and the intermetallic compound generated in situ, the powder metallurgy high-speed steel jointly hardened by the intermetallic compound and the carbonitride is obtained. Because the intermetallic compound and the matrix contain less carbon, the material can keep excellent red hardness and anti-knife-sticking performance, and meanwhile, the stable high-hardness carbonitride can play the roles of obviously refining grains and improving the wear resistance.

In order to achieve the technical purpose, the invention provides the intermetallic compound and carbonitride jointly strongly hardened powder metallurgy high-speed steel, the steel matrix is strengthened by the intermetallic compound generated in situ and the added carbonitride, and the intermetallic compound and carbide jointly strongly hardened powder metallurgy high-speed steel is obtained by a powder metallurgy method.

Preferably, the intermetallic compound is mainly generated in situ by metal elements of Fe, Co, Ni, Mo, W, Ti and Nb, and the added carbonitride is one or more of TiC, TiN, Ti (C, N), NbC, TaC, TaN, ZrC and ZrN.

In a preferred scheme, the intermetallic compound and carbide jointly strongly-hardened powder metallurgy high-speed steel is prepared from the following components in percentage by mass: co: 10-30%, Mo: 5-25%, W: 2-20% of carbonitride: 1-15% and the balance Fe.

More preferably, the intermetallic compound and carbide jointly strongly-hardened powder metallurgy high-speed steel is prepared from the following components in percentage by mass: co: 10-30%, Mo: 8-18%, W: 2-10%, carbonitride: 2-10% and the balance Fe.

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

The invention also provides a preparation method of the intermetallic compound and carbide jointly-strengthened hard powder metallurgy high-speed steel, which comprises the following specific steps:

1) obtaining raw material powder with corresponding mass fraction according to a formula, adding a forming agent and carbon black, performing ball milling, performing die pressing to obtain a pressed compact, performing vacuum sintering on the pressed compact, and performing sintering cooling to obtain a sintered compact;

2) heating and insulating the sintered blank obtained in the step 1) in an inert atmosphere, then carrying out hot processing, controlling pass deformation and compression ratio, annealing after thermal deformation is finished, and then cooling to room temperature along with the furnace;

3) preheating the sample obtained in the step 2), carrying out solid solution treatment, rapidly cooling the solid solution treatment to obtain a solid solution state sample, then carrying out cryogenic treatment, cooling to room temperature, and carrying out aging treatment to obtain a finished product.

Preferably, in the step 1), the forming agent is paraffin, the addition amount is 3-6 wt%, and the addition amount of the carbon black is 0.4-0.8 wt%.

In a preferred scheme, in the step 1), the ball milling mode is wet ball milling, the ball milling medium is alcohol, and the ball-to-material ratio is (3-6): 1. the ball milling can be carried out by planetary ball milling or roller ball milling, the rotating speed is 200-280 r/min when planetary ball milling is used, and the ball milling time is 48-60 h; the rotating speed is 80-120 r/min during roller ball milling, and the ball milling time is 72-86 h.

Preferably, in the step 1), the die pressing mode is bidirectional or unidirectional die pressing, and the pressure is 120-180 MPa.

In the preferable scheme, in the step 1), the sintering temperature is 1300-1400 ℃, and the sintering time is 1-3 h.

In the preferable scheme, in the step 2), the heating temperature before hot working is 1120-1180 ℃, the heat preservation time is 20-40 min, and the inert atmosphere is a nitrogen atmosphere or an argon atmosphere, so that the thermal deformation effect is prevented from being seriously influenced by the surface oxidation of the product.

Preferably, in the step 2), the hot working is selected from any one of hot forging, rolling and rotary forging, the pass deformation amount during the hot deformation is less than 5%, and the compression ratio during the hot deformation is 60-80%.

Through hot processing, micron-sized intermetallic compounds distributed in a net shape can be crushed and uniformly distributed in a matrix, a small amount of closed pores in the material can be forged, the density of the material is improved (more than 99.3 percent), and the mechanical property of the material is greatly improved.

In the preferable scheme, in the step 2), the annealing temperature is 750-900 ℃, and the annealing time is 1-3 h.

In the preferable scheme, in the step 3), preheating is carried out in a box type resistance furnace, the preheating temperature is 200-300 ℃, and the preheating time is 10-30 min.

In the preferable scheme, in the step 3), the solid solution treatment is carried out in a salt bath, the solid solution temperature is 1100-1250 ℃, the solid solution time is 15-30 min, and the cooling mode is oil cooling.

Preferably, in the step 3), the deep cooling is carried out in a deep cooling box, the deep cooling temperature is-100 to-80 ℃, and the deep cooling time is 1 to 3 hours.

In the preferable scheme, in the step 3), the aging treatment is carried out in a resistance furnace, the aging temperature is 500-700 ℃, the aging treatment frequency is 1-2 times, and the aging heat preservation time is 1-3 hours.

The intermetallic compound can be dissolved and precipitated again by the solid solution-aging treatment, and the distribution and size of the intermetallic compound phase can be adjusted. And the hardness of the blank after solutionizing falls below 45HRC and there is substantially no deformation of the material during the subsequent age hardening phase. Therefore, the difficulty of cutter processing can be greatly reduced by directly processing the solid-solution blank and then carrying out age hardening, the hardening is rapid in the aging process, and the hardness can be adjusted to 66-69HRC according to the aging process.

The intermetallic compound and the carbide jointly strongly harden the powder metallurgy high-speed steel prepared according to the scheme of the invention, the intermetallic compound phase and the carbide in the finished product are uniformly distributed, the matrix crystal grains are fine, the mechanical property and the wear resistance are excellent, and the steel has high hardness (66-69HRC), high strength (2500-²)。

Compared with the traditional high-speed steel, the intermetallic compound and carbide jointly hardened powder metallurgy high-speed steel prepared by the invention has the following advantages:

1. the intermetallic compound and the carbide are uniformly dispersed and distributed, the size of matrix grains is obviously reduced after the stable carbide is added, meanwhile, the obvious intermetallic compound phase is separated out around the carbide grains, the interface relation is good, and the intermetallic compound is prevented from being separated out along the grain boundary to form a network structure to a certain extent.

2. After the carbide is added, the carbide and the micron-sized intermetallic compound jointly form a wear-resistant phase, the mechanical property is excellent, and the wear resistance is greatly improved while the excellent tempering resistance is kept.

3. 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.

Drawings

FIG. 1 is a scanning electron microscope picture of a sintered state of Fe-Co-Mo series intermetallic compound reinforced high-speed steel prepared in comparative example 2 of the present invention;

FIG. 2 is a scanning electron microscope picture of a sintered state of a powder metallurgy high-speed steel jointly hardened by intermetallic compounds and carbides prepared in example 4 of the present invention;

FIG. 3 is a scanning electron microscope picture of the aging state finished product of the intermetallic compound and carbide co-strengthening powder metallurgy high-speed steel prepared in example 1;

FIG. 4 is a scanning electron microscope picture of the aging state finished product of the intermetallic compound and carbide co-strengthening powder metallurgy high-speed steel prepared in example 2;

FIG. 5 is a scanning electron microscope picture of the aging state finished product of the intermetallic compound and carbide co-strengthening powder metallurgy high-speed steel prepared in example 3.

Detailed Description

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