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Preparation method of powder metallurgy tool and mould steel

A tool steel and powder metallurgy technology, applied in the field of powder metallurgy tool and die steel preparation, can solve the problems of insufficient density of powder metallurgy products, poor dispersion of secondary carbides, etc., and achieve good toughness, plasticity, and organizational density. High, carbide dispersion effect

Active Publication Date: 2020-04-17
SOUTHEAST UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] Technical problem: The purpose of this invention is to provide a method for preparing powder metallurgy tool and die steel, which can obtain tool and die steel products with dense structure and uniform carbide dispersion, and solve the problem of insufficient density and secondary carbide dispersion of current powder metallurgy products. Poor and other issues

Method used

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Examples

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Effect test

preparation example Construction

[0027] The preparation method of a kind of powder metallurgy tool steel that the present invention adopts, concrete technology comprises the following steps:

[0028] Step 1) fully deoxidize and refine the molten steel of the tool and die, and control the oxygen content of the molten steel to be lower than 50ppm;

[0029] Step 2) Using high-purity nitrogen to fully atomize the molten steel in the atomization chamber, the nitrogen atomization pressure is 2-8 MPa, and the pressure in the atomization chamber is lower than 0.1 MPa;

[0030] Step 3) Sieve the tool and die steel powder, mix the powders with different particle sizes according to the set ratio, and put them into the package; ~10%, 15~35%, 20~50%, 10~20%;

[0031] Step 4) After evacuating the jacket, heat it to 300-500°C, and perform "vacuumizing + nitrogen filling" degassing treatment in a cycle. The number of cycles is not less than 3 times, and the vacuum degree is not higher than 0.1Pa each time, and the high-puri...

Embodiment 1

[0038] 1) The main components of powder metallurgy tool and die steel are as follows: ~1.3%C, 6.6%W, 5.3%Mo, 4.2%Cr, 3.3%V. After full deoxidation and refining of tool and die steel, the oxygen content is about 40ppm;

[0039] 2) High-purity nitrogen is used to fully atomize the molten steel in the atomization chamber, the nitrogen atomization pressure is 5MPa, and the pressure in the atomization chamber is 0.08MPa;

[0040] 3) Sieve the tool and die steel powder, mix the powders with different particle sizes in a certain proportion and put them into the bag. For alloy powders with particle sizes above 75 μm, 50-75 μm, 25-50 μm, and below 25 μm, 5% and 30% , 50%, 15% ratio mixing;

[0041] 4) Vacuum the bag, heat it to 400°C, and perform "vacuum pumping + nitrogen filling" degassing treatment. The number of cycles is 3 times, the vacuum degree is 0.06Pa, and the high-purity nitrogen gas is inflated for 40 minutes;

[0042] 5) After the above-mentioned sheath is sealed and we...

Embodiment 2

[0047] 1) The main components of powder metallurgy tool and die steel are as follows: ~1.3%C, 6.6%W, 5.3%Mo, 4.2%Cr, 3.3%V. After full deoxidation and refining of tool and die steel, the oxygen content is about 35ppm;

[0048] 2) High-purity nitrogen is used to fully atomize the molten steel in the atomization chamber, the nitrogen atomization pressure is 8MPa, and the pressure in the atomization chamber is 0.05MPa;

[0049] 3) Sieve the tool and die steel powder, mix the powders with different particle sizes in a certain proportion and put them into the bag. For alloy powders with particle sizes above 75 μm, 50-75 μm, 25-50 μm, and below 25 μm, 10% and 25% , 45%, 20% ratio mixing;

[0050] 4) Vacuum the bag, heat it to 500°C, and perform "vacuum pumping + nitrogen filling" degassing treatment. The number of cycles is 4 times, the vacuum degree is 0.08Pa, and the high-purity nitrogen gas is inflated for 30 minutes;

[0051] 5) After the above-mentioned sheath is sealed and wel...

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Abstract

The invention relates to a preparation method of powder metallurgy tool and mould steel. The structure density and carbide dispersity of the powder metallurgy tool and mould steel can be improved. Thepreparation method comprises the following main process steps that after the tool and mould steel is molten, sufficient deoxidation and refining are carried out, and the gas content of molten steel is controlled; high-purity nitrogen is adopted for sufficiently atomizing the molten steel in a high-vacuum-degree atomization chamber; the tool and mould steel is screened, and powder of different particle sizes is mixed according to a certain proportion and then is loaded in a sheath; vacuumizing and nitrogen filling gas removal treatment is carried out on the sheath cyclically, and the number oftimes of circulation is not smaller than 3; after rapid temperature increase treatment is carried out on the welded sheath, hot isostatic pressing is carried out; and after forging, rolling and otherhot machining are carried out on the powder metallurgy tool and mould steel, carbide desolvation pretreatment is carried out, and then finished product annealing is carried out. The tool and mould steel produced by the method is high in density, carbide is fine, dispersed and uniform, and products have high toughness and plasticity, high hardness and wear resistance.

Description

technical field [0001] The invention relates to a preparation method of powder metallurgy tool and die steel, in particular to a method for improving the microstructure density and carbide dispersion of powder metallurgy tool and die steel. Background technique [0002] Tool and die steel refers to high-speed steel and die steel, which has the advantages of high hardness and high wear resistance, and is widely used in the manufacture of cutting tools and precision molds. In order to ensure the performance requirements of tool and die steel, a large amount of carbon and alloy elements are added to tool and die steel to form a large number of hard and stable alloy carbides. However, at the same time, tool steel is prone to microstructure quality problems such as coarse primary carbides, uneven distribution, and segregation of banded structures, resulting in a decrease in hardness, red hardness, and wear resistance. [0003] The traditional tool and die steel production proces...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F9/08B22F1/00B22F3/15B22F3/24
CPCB22F9/082B22F3/15B22F3/24B22F2009/0824B22F2003/248B22F2998/10B22F1/052B22F1/14
Inventor 周雪峰张伟超刘凯文蒋建清朱小坤
Owner SOUTHEAST UNIV
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