阅读说明：本技术 一种高速钢粉末冶金制品的制备方法 (Preparation method of high-speed steel powder metallurgy product ) 是由 秦明礼 马志俊 贾宝瑞 陈刚 王帅帅 吴昊天 于 2021-08-09 设计创作，主要内容包括：本发明公开了一种高速钢粉末冶金制品的制备方法,属于粉末冶金材料领域。制备步骤为：1).称取一定比例的可溶性金属盐,制备金属离子溶液,均匀混合；2).加入一定比例的助燃剂,得到混合溶液；3).将混合溶液转移至炉中加热,低温燃烧合成制备金属氧化物混合粉末；4).将金属氧化物粉末在管式炉内还原气氛下煅烧,制备高速钢前驱体粉末；5).将制得的高速钢前驱体粉末进行制压成型,得到高速钢前驱体生坯；6).对高速钢前驱体生坯进行煅烧处理,得到烧结致密化的高速钢材料。该方法操作简便、成本低廉,适合工业推广,为制备高速钢粉末提供一种新的制备思路。(The invention discloses a preparation method of a high-speed steel powder metallurgy product, belonging to the field of powder metallurgy materials. The preparation steps are as follows: 1) weighing a certain proportion of soluble metal salt, preparing a metal ion solution, and uniformly mixing; 2) adding a combustion improver in a certain proportion to obtain a mixed solution; 3) transferring the mixed solution into a furnace for heating, and synthesizing and preparing metal oxide mixed powder by low-temperature combustion; 4) calcining the metal oxide powder in a reducing atmosphere in a tubular furnace to prepare high-speed steel precursor powder; 5) pressing and molding the prepared high-speed steel precursor powder to obtain a high-speed steel precursor green body; 6) and calcining the high-speed steel precursor green body to obtain the sintered and densified high-speed steel material. The method is simple and convenient to operate, low in cost and suitable for industrial popularization, and provides a new preparation idea for preparing the high-speed steel powder.)

1. A preparation method of a high-speed steel powder metallurgy product is characterized by comprising the following preparation steps:

1) weighing a certain proportion of soluble metal salt, preparing a metal ion solution, and uniformly mixing;

2) adding a combustion improver in a certain proportion to obtain a mixed solution;

3) transferring the mixed solution into a furnace for heating, and synthesizing and preparing metal oxide mixed powder by low-temperature combustion;

4) calcining the metal oxide powder in a reducing atmosphere in a tubular furnace to prepare high-speed steel precursor powder;

5) pressing and molding the prepared high-speed steel precursor powder to obtain a high-speed steel precursor green body;

6) and calcining the high-speed steel precursor green body to obtain the sintered and densified high-speed steel material.

2. The method for preparing a high-speed steel powder metallurgical product according to claim 1, wherein the soluble metal salt component in the step 1) comprises the following components in percentage by weight: 60-75% of ferric nitrate, 5-15% of cobalt nitrate, 5-15% of ammonium tungstate, 2-5% of chromium nitrate, 0.5-3% of ammonium molybdate and 0.5-2% of ammonium metavanadate.

3. The method for preparing a high-speed steel powder metallurgy product according to claim 1, wherein the metal ion solution in step 1) is prepared by adding ammonium nitrate in an amount of 15 to 25% by weight based on the total weight of the metal salts, adding water, and stirring until the ammonium nitrate is dissolved to obtain the metal ion solution.

4. The method for preparing a high-speed steel powder metallurgy product according to claim 1, wherein the proportion of the combustion improver in the step 2) is 60-200% of the mass of the metal salt, and the combustion improver comprises: one or more of glycine, urea and citric acid.

5. The method for preparing high-speed steel powder metallurgy products as claimed in claim 1, wherein the heating environment in step 3) is a temperature-controlled electric furnace or a muffle furnace, the temperature for heating the mixed solution is 180-.

6. The method for preparing a high-speed steel powder metallurgy product according to claim 1, wherein the atmosphere used for calcination in the reducing atmosphere in the step 4) is hydrogen, the heating temperature is 700-1200 ℃, the heating rate is 0.5-10 ℃/min, and the holding time is 1-5 h.

7. The method for preparing high-speed steel powder metallurgy products according to claim 1, wherein the step 5) of the compression molding process uses cold isostatic pressing at a pressure of 100-380 MPa.

8. The method for preparing a high-speed steel powder metallurgical product according to claim 1, wherein the calcination treatment in step 6) is performed by using a tubular furnace under the protection of methane gas, and the calcination temperature is as follows: 1100-1200 ℃; and (3) heat preservation time: 1-5 h; the heating rate is as follows: 1-10 deg.C/min.

Technical Field

The invention belongs to the field of powder metallurgy, and particularly relates to a preparation method of a high-speed steel powder metallurgy product.

Background

The high-speed steel is commonly called as high-speed steel, belongs to high-carbon high-alloy ledeburite steel, has high hardness, high wear resistance and excellent red hardness, and is widely applied to manufacturing various machine tool cutting tools, aviation high-temperature bearings, heat-resistant and wear-resistant parts and the like. The preparation process of the high-speed steel mainly comprises the traditional casting process, the powder metallurgy process and the like. The traditional casting process can generate segregation due to slow solidification speed, thereby generating massive carbides or network carbides and restricting the improvement of the performance of high-speed steel. The powder metallurgy process can effectively solve the segregation problem of the traditional process, the carbide of the powder high-speed steel is fine and uniform, and the strength, the plasticity and the wear resistance of the powder high-speed steel are greatly improved compared with those of cast high-speed steel.

The quality of the high-speed steel is closely related to the types and the contents of alloy elements in the high-speed steel, and except C, the main alloy elements in the high-speed steel comprise W, Mo, V, Cr, Co and the like. The C element can form carbide with alloy elements, so that the hardness of martensite after quenching can be ensured, and the body strength is improved. W can generate a large amount of W in high-speed steel₆The C-type carbide pins the grain boundary, and plays a role in inhibiting the growth of austenite grains during quenching heating, thereby increasing the quenching temperature. Mo acts in high-speed steel similarly to W, and the resulting carbide structure is similar, so that Mo and W can be substituted for each other. Cr generation in high speed steel₂₃C₆The carbon content of the austenite is increased by dissolving in the austenite during heating, and the stability of the supercooled austenite is improved, thereby improving the hardenability of the high-speed steel. V is the strongest carbide-forming element in high-speed steel, and in the high-speed steel, one part of V is dissolved in the matrix in a solid mode, is precipitated by the matrix in a desolvation mode in a tempering process, and the other part of V exists in a VC mode. Finally, Co is not a carbide forming element, and most of Co is dissolved in the matrix in the high-speed steel, so that the nucleation speed of the carbide can be increased, and the growth speed of the carbide is slowed down, thereby improving the red hardness of the high-speed steel and enhancing the secondary hardening effect.

The low-temperature combustion synthesis method is to generate a powder material by utilizing the exothermic combustion reaction of an oxidant and a fuel in a solution. The advantages are that it can ensure the components to be mixed evenly and the components to be controlled accurately. The low-temperature combustion synthesis method is suitable for preparing the nano powder with high specific surface area, has high reaction speed and is suitable for industrial production.

Based on the factors, the invention provides a preparation method of a high-speed steel powder metallurgy product. The high-speed steel precursor powder is prepared by adopting a low-temperature combustion synthesis method, the preparation is rapid, the components are uniform, the prepared powder is loose and easy to crush, the sintering activity is very high, the sintering temperature is greatly reduced, the sintering time is reduced, and the industrial large-scale production is facilitated.

Disclosure of Invention

The invention aims to provide a preparation method of a novel high-speed steel powder metallurgy product. The high-speed steel material is prepared by a powder metallurgy method, and the prepared high-speed steel carbide is fine and uniform, and the strength, the plasticity and the wear resistance of the high-speed steel are greatly improved compared with those of cast high-speed steel.

A preparation method of a high-speed steel powder metallurgy product comprises the following preparation steps:

1) weighing a certain proportion of soluble metal salt, preparing a metal ion solution, and uniformly mixing;

2) adding a combustion improver in a certain proportion to obtain a mixed solution;

3) transferring the mixed solution into a furnace for heating, and synthesizing and preparing metal oxide mixed powder by low-temperature combustion;

4) calcining the metal oxide powder in a reducing atmosphere in a tubular furnace to prepare high-speed steel precursor powder;

5) pressing and molding the prepared high-speed steel precursor powder to obtain a high-speed steel precursor green body;

6) and calcining the high-speed steel precursor green body to obtain the sintered and densified high-speed steel material.

Further, the soluble metal salt component and the mixture ratio in the step 1) are as follows (weight percentage): 60-75% of ferric nitrate, 5-15% of cobalt nitrate, 5-15% of ammonium tungstate, 2-5% of chromium nitrate, 0.5-3% of ammonium molybdate and 0.5-2% of ammonium metavanadate.

Further, the preparation process of the metal ion solution in the step 1) is to add ammonium nitrate accounting for 15-25% of the total weight of the metal salt, add water and stir until the ammonium nitrate is dissolved to obtain the metal ion solution.

Further, the proportion of the combustion improver in the step 2) is 60-200% of the mass of the metal salt, and the combustion improver comprises: glycine, urea, citric acid, and the like;

further, the heating environment in the step 3) can use a temperature-controlled electric furnace or a muffle furnace, the temperature for heating the mixed solution is 180-;

further, the atmosphere used for calcination in the reducing atmosphere in the step 4) is hydrogen, the heating temperature is 700-1200 ℃, the heating rate is 0.5-10 ℃/min, and the heat preservation time is 1-5 h.

Further, the compression molding process in the step 5) uses cold isostatic pressing, and the pressure is 100-380 MPa.

Further, the calcination treatment in step 6) is implemented by using a tubular furnace under the protection of methane gas, wherein the calcination temperature is as follows: 1100-1200 ℃; and (3) heat preservation time: 1-5 h; the heating rate is as follows: 1-10 deg.C/min.

The invention has the following beneficial effects:

the invention uses a low-temperature combustion synthesis method to prepare high-speed steel powder, metal ions are uniformly mixed, the components in a reaction product are uniformly distributed, and particles are fine and are not easy to agglomerate. And secondly, the gas generated in the combustion process can loosen and expand the powder, so that the powder can be refined, and the sintering activity of the powder can be improved. And finally, the low-temperature combustion synthesis is simple and convenient to operate, short in synthesis time and high in product efficiency, and is suitable for industrial popularization.

Detailed Description

Example 1

70g of iron nitrate, 12g of cobalt nitrate, 12g of ammonium tungstate, 4g of chromium nitrate, 1g of ammonium molybdate, and 1g of ammonium metavanadate were charged into a beaker having a volume of 2L. 18g ammonium nitrate, 80g glycine, 40g urea and 200ml deionized water were added and stirred with a glass rod until the precipitate was completely dissolved. And transferring the mixed solution to a temperature-controlled electric furnace, heating the solution at 250 ℃, boiling and evaporating the solution until the solution is spread and combusted, and collecting powder after the solution is fully combusted to obtain metal oxide powder. And transferring the obtained metal oxide powder into a tubular furnace, heating to 800 ℃ at a heating rate of 8 ℃/min under the protection of hydrogen atmosphere, and preserving heat for 2h to obtain the reduced high-speed steel precursor powder. And (3) pressing the high-speed steel precursor powder subjected to hydrogen reduction into a high-speed steel precursor green body by adopting a cold isostatic pressing mode, wherein the pressure is 200 MPa. And finally, transferring the prepared high-speed steel precursor green body into a tubular furnace, and carrying out heat preservation for 2h at 1150 ℃ under the condition that methane is used as protective atmosphere and the heating rate is 8 ℃/min.

Example 2

75g of iron nitrate, 10g of cobalt nitrate, 10g of ammonium tungstate, 3g of chromium nitrate, 1g of ammonium molybdate, and 1g of ammonium metavanadate were charged into a beaker having a volume of 2L. Then, 15g of ammonium nitrate, 100g of glycine and 200ml of deionized water were added thereto, and the mixture was stirred with a glass rod until the precipitate was completely dissolved. And transferring the mixed solution to a temperature-controlled electric furnace, heating the solution at 220 ℃, boiling and evaporating the solution until the solution is spread and combusted, and collecting powder after the solution is fully combusted to obtain metal oxide powder. And transferring the obtained metal oxide powder into a tubular furnace, heating to 800 ℃ at a heating rate of 8 ℃/min under the protection of hydrogen atmosphere, and preserving heat for 2h to obtain the reduced high-speed steel precursor powder. And (3) pressing the high-speed steel precursor powder subjected to hydrogen reduction into a high-speed steel precursor green compact by adopting a cold isostatic pressing mode, wherein the pressure is 220 MPa. And finally, transferring the prepared high-speed steel precursor green body into a tubular furnace, and carrying out heat preservation for 2h at 1150 ℃ under the condition that methane is used as protective atmosphere and the heating rate is 8 ℃/min.

Example 3

70g of iron nitrate, 12g of cobalt nitrate, 12g of ammonium tungstate, 4g of chromium nitrate, 1g of ammonium molybdate, and 1g of ammonium metavanadate were charged into a beaker having a volume of 2L. 18g ammonium nitrate, 70g glycine, 40g urea, 20g citric acid and 200ml deionized water were added and stirred with a glass rod until the precipitate was completely dissolved. And transferring the mixed solution to a temperature-controlled electric furnace, heating the solution at 250 ℃, boiling and evaporating the solution until the solution is spread and combusted, and collecting powder after the solution is fully combusted to obtain metal oxide powder. And transferring the obtained metal oxide powder into a tubular furnace, heating to 900 ℃ at a heating rate of 3 ℃/min under the protection of hydrogen atmosphere, and preserving heat for 1h to obtain the reduced high-speed steel precursor powder. And (3) pressing the high-speed steel precursor powder subjected to hydrogen reduction into a high-speed steel precursor green body by adopting a cold isostatic pressing mode, wherein the pressure is 200 MPa. And finally, transferring the prepared high-speed steel precursor green body into a tubular furnace, and carrying out heat preservation for 2h at 1150 ℃ under the condition that methane is used as protective atmosphere and the heating rate is 8 ℃/min.