A method for producing a high speed steel composite

Abstract

The application relates to a preparation method of a high-speed steel composite material, which comprises the following steps: mixing high-speed steel powder, Mo2C particles, graphite powder and a binder, drying after ball milling to obtain mixed powder; wherein the high-speed steel powder is CrCoMoV high-speed steel powder; the mixed powder is die formed to obtain a powder compact; the powder compact is sintered under an argon atmosphere to obtain a sintered body; the sintered body is sintered under vacuum conditions, and then cooled to obtain the high-speed steel composite material. The high-speed steel composite material prepared by the method has many excellent characteristics such as small microstructure grain, uniform particle distribution, high density, high hardness, high bending strength and the like, and has the advantages of cost reduction and efficiency increase.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a high-speed steel composite material, in particular to a method for preparing a Mo2C particle reinforced powder high-speed steel composite material based on an argon-vacuum pressureless sintering process, and belongs to the alloy field. BACKGROUND

[0002] 10Cr15CoMoV is a high-alloy high-speed steel, and the chemical composition and the mass percentage of each component are as follows: C: 0.9-1.1%, Cr: 14.5-15.5%, Mo: 0.8-1.2%, V: 0.2-0.4%, Co: 1.3-1.8%, and the balance is iron and impurities. 10Cr15CoMoV is widely used in high-end cutting tools, precision bearings and medical devices and other fields with extremely strict material performance requirements due to its excellent high hardness, corrosion resistance and wear resistance.

[0003] At present, the main industrial production methods of CrCoMoV alloy materials are melting casting (such as CN117619880A, CN119640149A and CN119040727A) and powder metallurgy (such as CN118989325B, CN119501070A and CN119501070A). However, the traditional melting casting method has the following significant defects: 1. The solidification rate is slow, and the alloy carbide is easy to precipitate along the grain boundary to form a coarse network carbide; 2. The alloy liquid condensation time is different, which is easy to cause composition segregation and residual stress, resulting in the initiation of internal cracks of the metal; 3. Inadequate degassing, which is easy to form pores and shrinkage. The powder metallurgy method often uses high-pressure inert gas or water atomization technology to atomize the steel liquid into micron-sized powder particles, and then sintered into a shape in a vacuum. Due to the rapid solidification of the powder particles, the carbide cannot form a coarse network structure along the grain boundary during the solidification process, but is embedded in the matrix in a uniform and dispersed manner, so that it is difficult to effectively improve the mechanical properties.

[0004] Particle reinforced phase alloy steel adds different contents of hard phases such as carbides, nitrides and borides during the sintering stage of the steel, so as to further enhance the strength, hardness and wear resistance of the material. For example, Chinese invention patent application CN114457291A adds TiC particles in the high-speed steel main material, and prepares a high-wear-resistant composite powder high-speed steel at 1180 DEG C and a pressure of 150 MPa. Chinese invention patent application CN110273096A adds nano-sized SiC particles in the M2 powder high-speed steel, and obtains a high-speed steel composite material with a relative density of >98.5%, but it needs to go through a complex heat treatment process after sintering. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a preparation method of high-speed steel composite material, so as to obtain high-speed steel composite material with high density and excellent mechanical properties.

[0006] In order to solve the above technical problems, the technical scheme of the present application is as follows:

[0007] A preparation method of high-speed steel composite material, comprising the following steps:

[0008] S1, high-speed steel powder, Mo2C particles, graphite powder, binder are mixed according to the mass ratio of 100:5-7:0.2-0.7:1.8-2.5, after ball milling, drying, obtaining mixed powder;

[0009] The high-speed steel powder is CrCoMoV high-speed steel powder.

[0010] S2, the mixed powder is formed by die pressing, obtaining powder compact;

[0011] S3, the powder compact is sintered under argon atmosphere, obtaining sintered body;

[0012] S4, the sintered body is sintered under vacuum condition, cooling, obtaining high-speed steel composite material.

[0013] Further, in S1, the high-speed steel powder is obtained by gas atomization.

[0014] Optionally, in S1, the preparation method of high-speed steel powder comprises the following steps:

[0015] (1) according to the composition of high-speed steel powder, the steel raw material is added into the smelting furnace, and chromium iron, molybdenum iron, vanadium iron, cobalt iron and other alloys are added, the composition is adjusted, and the molten steel is obtained by smelting and holding at 1550-1600℃.

[0016] (2) nitrogen gas atomization is used for the molten steel, the atomization nozzle pressure is 2-5MPa, the atomization temperature is 1580-1600℃, and the spherical high-speed steel powder with diameter <100μm is obtained.

[0017] Further, in S1, the high-speed steel powder is spherical; the particle size of the high-speed steel powder is <100μm; the particle size of the Mo2C particles is less than 1μm; and the binder is liquid paraffin.

[0018] Further, in S1, the high-speed steel powder is 10Cr15CoMoV powder.

[0019] Further, in S1, the high speed steel powder comprises C: 0.9-1.1%, Cr: 14.5-15.5%, Mo: 0.8-1.2%, V: 0.2-0.4%, Co: 1.3-1.8%, and the balance of iron and inevitable impurities.

[0020] Further, in S1, the ball milling is performed by using a planetary ball mill, and the ball milling speed is 250-300 r / min, and the ball milling time is 2-6 h.

[0021] Further, in S1, during the ball milling, anhydrous alcohol is added as the ball milling medium; drying is performed at 80-100 ℃; and stirring is performed during the drying. Alternatively, the heating and stirring are performed in a stirring machine to realize the drying and stirring simultaneously.

[0022] Further, in S1, the high speed steel powder, Mo2C particles, graphite powder and binder are mixed in a mass ratio of 100: 5.5-6.5: 0.3-0.6: 2-2.3.

[0023] Further, in S1, the high speed steel powder, Mo2C particles, graphite powder and binder are mixed in a mass ratio of 100: 5.8-6.2: 0.4-0.5: 2.1-2.2.

[0024] Further, in S2, the mixed powder is added into a mold, and the mixed powder is pressed at a load of 80-150 MPa for 15-25 s, and then demolded to obtain a powder compact. Further, the mixed powder is pressed at a load of 90-140 MPa for 18-22 s.

[0025] Alternatively, in S3, the flow rate of the argon gas is controlled to be 300-500 ml / min, further 350-450 ml / min, and further 380-420 ml / min.

[0026] Further, in S3, the sintering is performed according to the following procedure: first, sintering at 300-400 ℃ for 0.5-1.5 h, then increasing the temperature to 650-750 ℃, maintaining the temperature for 15-25 min, then increasing the temperature to 850-1000 ℃, maintaining the temperature for 45-75 min, and cooling to obtain a sintered body.

[0027] Further, in S3, the sintering is performed according to the following procedure: first, increasing the temperature to 300-400 ℃ at a rate of 8-12 ℃ / min, sintering for 0.8-1.2 h, then increasing the temperature to 650-750 ℃ at a rate of 8-12 ℃ / min, maintaining the temperature for 18-22 min, then increasing the temperature to 850-1000 ℃ at a rate of 3-7 ℃ / min, maintaining the temperature for 50-70 min, and cooling to obtain a sintered body.

[0028] Further, in S4, sintering is performed according to the following procedure: first, heating to 350-450℃ at a rate of 8-12℃ / min, holding for 18-22min; heating to 750-850℃ at a rate of 8-12℃ / min, holding for 18-22min; then heating to 950-1050℃ at a rate of 3-7℃ / min, holding for 18-22min, and heating to 1250-1350℃ at a rate of 2-4℃ / min, holding for 50-70min, and then cooling, to obtain the high-speed steel composite material.

[0029] Further, in S4, sintering is performed according to the following procedure: first, heating to 350-450℃ at a rate of 8-12℃ / min, holding for 18-22min; heating to 750-850℃ at a rate of 8-12℃ / min, holding for 18-22min; then heating to 950-1050℃ at a rate of 3-7℃ / min, holding for 18-22min, and heating to 1250-1350℃ at a rate of 2-4℃ / min, holding for 50-70min, and then cooling, to obtain the high-speed steel composite material.

[0030] Optionally, in S4, the vacuum degree is 0.001-0.1 MPa, further 0.01-0.08 MPa, and more further 0.03-0.06 MPa.

[0031] Optionally, after S4, the high-speed steel composite material is heat treated to further improve its mechanical properties.

[0032] The present application aims at the deficiencies of the current CrCoMoV high-speed steel composite material melt-casting preparation technology, and proposes a preparation method of Mo2C particle reinforced CrCoMoV system powder high-speed steel composite material. The method can effectively improve the performance of the high-speed steel composite material, so that the prepared high-speed steel composite material has many excellent characteristics such as small microstructure grain, uniform particle distribution, high density, high hardness, and bending strength, etc., the hardness can be above 785HV, the bending strength can be above 870MPa, and the relative density can be above 98%; at the same time, it is helpful to reduce the sintering densification temperature, reduce the production cost, improve the production efficiency, and has significant cost reduction and efficiency improvement advantages. In addition, the high-speed steel composite material obtained by the present application can be further heat treated to obtain better mechanical properties. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is the SEM image of the high-speed steel composite material of Comparative Example 9 in the present application.

[0034] Figure 2 is the SEM image of the high-speed steel composite material of Comparative Example 1 in the present application.

[0035] Figure 3is a SEM image of the high speed steel composite material of Example 1 in the present application. DETAILED DESCRIPTION

[0036] The present application will be described in detail below with reference to examples. It should be noted that the examples in the present application and the features in the examples can be combined with each other without conflict. If not specifically stated, the relevant percentages refer to mass percentages.

[0037] Example 1

[0038] The preparation method of the high speed steel composite material of the present example is as follows:

[0039] Step 1: Add steel raw materials into a smelting furnace, and after the composition is uniform, perform heat preservation smelting at 1550℃ to obtain molten steel.

[0040] The composition of the molten steel is: C: 0.9%, Cr: 14.5%, Mo: 1.2%, V: 0.4%, Co: 1.8%, and the balance is iron and impurity alloy elements.

[0041] Step 2: Perform atomization treatment on the smelted molten steel by using nitrogen, control the atomization nozzle pressure at 2MPa, and maintain the atomization temperature at 1580℃ to obtain spherical high speed steel powder (10Cr15CoMoV powder) with a diameter of less than 100μm.

[0042] Step 3: Add 6wt% Mo2C particles (diameter less than 1μm, i.e. 6wt% of the spherical high speed steel powder), 0.6wt% graphite powder (i.e. 0.6wt% of the spherical high speed steel powder), and 1.8wt% liquid paraffin (i.e. 1.8wt% of the spherical high speed steel powder) into the spherical high speed steel powder, mix uniformly, and then place in a planetary ball mill, add anhydrous alcohol (the amount added is appropriate to cover the powder) to optimize the mixing effect, wet mix for 4 hours at a speed of 250r / min, then transfer to a stirrer, continuously stir for 2 hours in a heating environment at 80℃, and finally naturally air dry to obtain a mixed powder.

[0043] Step 4: Put the mixed powder into a powder pressing mold, and press at a pressure of 80MPa, keep pressure for 20s, and then demold to obtain a powder compact.

[0044] Step 5: Put the powder compact into an atmosphere tube furnace, introduce argon gas, control the argon gas flow rate at 300ml / min, start the temperature rising program: first increase the temperature from room temperature to 350℃ at a rate of 10℃ / min, keep for 1 hour; then increase the temperature to 700℃ at the same rate, keep for 20 minutes; then increase the temperature to 950℃ at a rate of 5℃ / min, keep for 1 hour, and then cool to room temperature to obtain a sintered body.

[0045] Step 6: The sintered body is moved to a vacuum sintering furnace and sintered under a vacuum degree of 1x10 -3 Mpa. The sintering procedure is as follows: first, the temperature is raised from room temperature to 400℃ at a rate of 10℃ / min, and the pre-sintering treatment is performed for 20 minutes; then, the temperature is continuously raised to 800℃ at a rate of 10℃ / min, and the intermediate stage sintering is performed for 20 minutes at 800℃; next, the temperature is raised to 1000℃ at a rate of 5℃ / min, and the temperature is maintained for 20 minutes to promote material densification; thereafter, the temperature is raised to 1275℃ at a rate of 3℃ / min, and the temperature is maintained for 60 minutes to achieve sufficient densification and performance optimization of the material (sufficient densification sintering stage); finally, the furnace is cooled to room temperature to complete the entire sintering process, and a high-speed steel composite material is obtained.

[0046] It is detected that the hardness of the obtained high-speed steel composite material is 803.4HV (determined by a Vickers hardness tester, the same below), the bending strength is 1366.5MPa (determined by a mechanical property testing machine, the same below), and the relative density is 99.87% (determined by the Archimedes drainage method, the same below).

[0047] Example 2

[0048] The preparation method of the high-speed steel composite material of this embodiment is as follows:

[0049] Step 1: Add steel raw materials into a smelting furnace, and after the composition is uniform, perform heat preservation smelting at 1550℃ to obtain molten steel.

[0050] The composition of the molten steel is as follows: C: 0.9%, Cr: 14.5%, Mo: 1.2%, V: 0.4%, Co: 1.8%, and the balance is iron and impurity alloy elements.

[0051] Step 2: Perform atomization treatment on the smelted molten steel by using nitrogen, the atomization nozzle pressure is controlled at 3.5MPa, and the atomization temperature is maintained at 1590℃ to obtain spherical high-speed steel powder (10Cr15CoMoV powder) with a diameter of less than 100μm.

[0052] Step 3: Add 6wt% Mo2C particles (diameter less than 1μm, i.e. 6wt% of the spherical high-speed steel powder), 0.3wt% graphite powder (i.e. 0.3wt% of the spherical high-speed steel powder), and 1.8wt% liquid paraffin (i.e. 1.8wt% of the spherical high-speed steel powder) into the spherical high-speed steel powder, mix uniformly, and then place in a planetary ball mill, add anhydrous alcohol (the amount added is appropriate to cover the powder) to optimize the mixing effect, wet mix for 4 hours at a speed of 275r / min, then transfer to a stirrer, continuously stir for 2 hours in a heating environment of 90℃, and finally naturally air dry to obtain the mixed powder.

[0053] Step 4: The mixed powder was loaded into a powder pressing mold and pressed at a pressure of 115 MPa, with a holding time of 20 s, and then demolded to obtain a green compact.

[0054] Step 5: The green compact was placed in an atmosphere tube furnace, and argon was introduced at a flow rate of 400 ml / min. The temperature program was started by first increasing the temperature from room temperature to 350℃ at a rate of 10℃ / min, holding for 1 hour; then increasing the temperature to 700℃ at the same rate, holding for 20 minutes; then increasing the temperature to 950℃ at a rate of 5℃ / min, holding for 1 hour, and then cooling to room temperature to obtain a sintered body.

[0055] Step 6: The sintered body was moved to a vacuum sintering furnace and sintered under a vacuum of 1×10 -3 Mpa. The sintering program was as follows: first, the temperature was increased from room temperature to 400℃ at a rate of 10℃ / min, holding for 20 minutes for pre-sintering treatment; then, the temperature was continued to increase to 800℃ at a rate of 10℃ / min, holding for 20 minutes for intermediate stage sintering; then, the temperature was increased to 1000℃ at a rate of 5℃ / min, holding for 20 minutes to promote material densification; then, the temperature was increased to 1300℃ at a rate of 3℃ / min, holding for 60 minutes to achieve full densification and performance optimization of the material (full densification sintering stage); finally, the furnace was cooled to room temperature to complete the entire sintering process, and a high-speed steel composite material was obtained.

[0056] The hardness of the obtained high-speed steel composite material was 785.8HV, the bending strength was 1357.3MPa, and the relative density was 99.43%.

[0057] Comparative Example 1

[0058] Example 1 was repeated, except that in Step 3, Mo2C particles and graphite powder were not added.

[0059] The hardness of the obtained high-speed steel composite material was 137HV, the bending strength was 280MPa, and the relative density was 90.3%.

[0060] Comparative Example 2

[0061] Example 1 was repeated, except that in Step 3, Mo2C particles and graphite powder were not added, and in Step 6, the temperature was controlled to increase to 1450℃ in the full densification sintering stage.

[0062] The hardness of the obtained high-speed steel composite material was 586HV, the bending strength was 1512MPa, and the relative density was 98.9%.

[0063] It can be seen that the addition of Mo2C particles and graphite powder helps to obtain high relative density of the high speed steel composite at a lower sintering temperature, which helps to save energy, improve production efficiency and reduce cost.

[0064] Comparative Example 3

[0065] Example 1 was repeated, except that in step 3, the addition amount of Mo2C particles was 0 and the addition amount of graphite powder was 0.6wt%.

[0066] It was detected that the hardness of the obtained high speed steel composite was 682HV, the bending strength was 1467.2MPa, and the relative density was 99.69%.

[0067] Comparative Example 4

[0068] Example 1 was repeated, except that in step 3, the addition amount of Mo2C particles was 0 and the addition amount of graphite powder was 0.9wt%.

[0069] It was detected that the hardness of the obtained high speed steel composite was 378HV, the bending strength was 800.1MPa, and the relative density was 98.47%.

[0070] Comparative Example 5

[0071] Example 1 was repeated, except that in step 3, the addition amount of Mo2C particles was 0 and the addition amount of graphite powder was 0.9wt%. In step 6, the temperature was controlled to rise to 1350℃ in the full densification sintering stage.

[0072] It was detected that the hardness of the obtained high speed steel composite was 686HV, the bending strength was 1034.8MPa, and the relative density was 99.49%.

[0073] Comparative Example 6

[0074] Example 1 was repeated, except that in step 3, the addition amount of Mo2C particles was 6wt% and the addition amount of graphite powder was 0.

[0075] It was detected that the hardness of the obtained high speed steel composite was 196.6HV, the bending strength was 448MPa, and the relative density was 92.45%.

[0076] Comparative Example 7

[0077] Example 1 was repeated, except that in step 3, the addition amount of graphite powder was 0 and the addition amount of Mo2C particles was 3wt%.

[0078] It was detected that the hardness of the obtained high speed steel composite was 293HV, the bending strength was 357MPa, and the relative density was 91.6%.

[0079] Comparative Example 8

[0080] Example 1 was repeated, except that in step 3, the graphite powder was added in an amount of 0, and the Mo2C particles were added in an amount of 3wt%. In step 6, the temperature was controlled to rise to 1425°C in the fully densification sintering stage.

[0081] The hardness of the high speed steel composite material obtained was 655HV, the bending strength was 1378MPa, and the relative density was 98.91%.

[0082] Comparative Example 9

[0083] Example 1 was repeated, except that in step 3, the graphite powder was added in an amount of 0, and the Mo2C particles were added in an amount of 6wt%. In step 6, the temperature was controlled to rise to 1425°C in the fully densification sintering stage.

[0084] The hardness of the high speed steel composite material obtained was 742.8HV, the bending strength was 1452MPa, and the relative density was 98.92%.

[0085] Comparative Example 10

[0086] Example 1 was repeated, except that in step 3, the graphite powder was added in an amount of 0.3wt%, and the Mo2C particles were added in an amount of 0wt%.

[0087] The hardness of the high speed steel composite material obtained was 250.2HV, the bending strength was 177.6MPa, and the relative density was 95.44%.

[0088] Example 3

[0089] Example 1 was repeated, except that in step 3, the graphite powder was added in an amount of 0.3wt%, and the Mo2C particles were added in an amount of 6wt%. In step 6, the temperature was controlled to rise to 1275°C in the fully densification sintering stage.

[0090] The hardness of the high speed steel composite material obtained was 792.8HV, the bending strength was 877.7MPa, and the relative density was 98.44%.

[0091] Example 4

[0092] Example 1 was repeated, except that in step 3, the graphite powder was added in an amount of 0.3wt%, and the Mo2C particles were added in an amount of 6wt%. In step 6, the temperature was controlled to rise to 1350°C in the fully densification sintering stage.

[0093] The hardness of the high speed steel composite material obtained was 819.3HV, the bending strength was 870MPa, and the relative density was 99.87%.

[0094] It can be seen that, in the full densification sintering stage, controlling the appropriate temperature helps to obtain high-speed steel composite material with more excellent bending strength and hardness.

[0095] Example 5

[0096] Example 1 is repeated, except that in step 6, the temperature is controlled to rise to 1300℃ in the full densification sintering stage.

[0097] It is detected that the hardness of the obtained high-speed steel composite material is 813HV, the bending strength is 880.6MPa, and the relative density is 99.86%.

[0098] Example 6

[0099] Example 1 is repeated, except that in step 3, in step 6, the temperature is controlled to rise to 1350℃ in the full densification sintering stage.

[0100] It is detected that the hardness of the obtained high-speed steel composite material is 915.5HV, the bending strength is 809MPa, and the relative density is 99.76%.

[0101] Comparative Example 11

[0102] Example 1 is repeated, except that in step 3, the addition amount of graphite powder is 0.9wt%, and the addition amount of Mo2C particles is 6wt%.

[0103] It is detected that the hardness of the obtained high-speed steel composite material is 396HV, the bending strength is 128.5MPa, and the relative density is 94.07%.

[0104] It can be seen that, the addition amount of graphite powder and Mo2C is too high, which is also not conducive to the improvement of hardness, bending strength and relative density.

[0105] Comparative Example 12

[0106] Example 1 is repeated, except that in step 3, the addition amount of graphite powder is 0.9wt%, and the addition amount of Mo2C particles is 6wt%. In step 6, the temperature is controlled to rise to 1350℃ in the full densification sintering stage.

[0107] It is detected that the hardness of the obtained high-speed steel composite material is 610.5HV, the bending strength is 457.3MPa, and the relative density is 97.2%.

[0108] It can be seen that, the addition amount of graphite powder and Mo2C is too high, which is also not conducive to the improvement of hardness, bending strength and relative density.

[0109] The above embodiments should be understood as being used only for more clearly describing the present application, and not for limiting the scope of the present application, and after reading the present application, various equivalent modifications of the present application by those skilled in the art fall within the scope of the appended claims.

Claims

1. A method for preparing a 10Cr15CoMoV high speed steel composite material, characterized in that, The method comprises the following steps: S1, mixing high-speed steel powder, Mo2C particles, graphite powder and binder according to a mass ratio of 100:5-7:0.2-0.7:1.8-2.5, ball milling, drying to obtain mixed powder; The high-speed steel powder is 10Cr15CoMoV powder. S2, molding the mixed powder to obtain a powder compact; S3, sintering the powder compact in an argon atmosphere to obtain a sintered body; S4, sintering the sintered body in a vacuum condition, and cooling to obtain a 10Cr15CoMoV high-speed steel composite material. In S4, the sintering is performed according to the following procedure: first, heating to 350-450 DEG C, holding for 15-25 min; then, heating to 750-850 DEG C, holding for 15-25 min; then, heating to 950-1050 DEG C, holding for 15-25 min; then, heating to 1250-1350 DEG C, holding for 45-75 min, and cooling to obtain the high-speed steel composite material.

2. The production method according to claim 1, characterized by, In S1, the high-speed steel powder is obtained by gas atomization.

3. The preparation method according to claim 1, characterized in that, In S1, the high-speed steel powder is spherical, the particle size of the high-speed steel powder is less than 100 mu m, the particle size of the Mo2C particles is less than 1 mu m, and the binder is liquid paraffin.

4. The production method according to claim 1, characterized by, In S1, the planetary ball mill is used for ball milling, the ball milling speed is 250-300 r / min, and the ball milling time is 2-6 h.

5. The method of claim 1, wherein, In S1, anhydrous alcohol is added as a ball milling medium during ball milling, and the mixture is dried at 80-100 DEG C; during the drying, stirring is performed.

6. The method of claim 1, wherein, In S1, the high-speed steel powder, Mo2C particles, graphite powder and binder are mixed according to a mass ratio of 100:5.5-6.5:0.3-0.6:2-2.

3.

7. The preparation method according to claim 1, characterized in that, In S2, the mixed powder is added into a mold, and is pressed at a load of 80-150 MPa for 15-25 s, and then demolded to obtain a powder compact.

8. The method of any one of claims 1-7, wherein, In S3, the sintering is performed according to the following procedure: first, sintering at 300-400 DEG C for 0.5-1.5 h, then, heating to 650-750 DEG C, holding for 15-25 min, then, heating to 850-1000 DEG C, holding for 45-75 min, and cooling to obtain the sintered body.

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