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Preparation method for powder metallurgy wear-resisting stainless steel

A technology of powder metallurgy and stainless steel, applied in metal material coating process, coating, solid-state diffusion coating, etc., can solve the problems of high nitrogen stainless steel powder price, poor pressing performance, high manufacturing cost, etc., and achieve high nitrogen content and Effects of hardness, thickness increase, and cost reduction

Active Publication Date: 2015-12-23
NBTM NEW MATERIALS GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] With the first method, due to the high price of high-nitrogen stainless steel powder and poor pressing performance, this preparation method has high manufacturing costs and cannot directly manufacture products with complex shapes.
Using the second method, since nitrogen-containing stainless steel materials are prepared by using a nitrogen-containing atmosphere during the sintering process, such as nitrogen or decomposed ammonia, the amount of nitrogen infiltration is very limited, and the macroscopic hardness is usually lower than HRC20, so the wear resistance of powder metallurgy stainless steel The improvement is also very limited

Method used

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Embodiment 1

[0037] The preparation method of powder metallurgy wear-resistant stainless steel in this embodiment comprises the following steps:

[0038] (1) if figure 1 As shown, 100 mesh 434L stainless steel powder is mixed with graphite powder and organic lubricant to obtain mixed powder. In terms of weight percentage, the content of graphite powder in the mixed powder is 0.2wt%, and the content of organic lubricant is 0.5wt%. Avoid impurity content not exceeding 2wt%;

[0039](2) Put the mixed powder obtained in step (1) into a mold for compaction to obtain a powder metallurgy green body, the forming pressure is 600MPa, and the green body density after forming is 6.4g / cm 3 ;

[0040] (3) The powder metallurgy green body obtained in step (2) is placed in a push rod furnace, and the volume ratio is 1:1 of H 2 with N 2 Sintering is carried out under the protection of a mixed atmosphere, the sintering temperature is 1250°C, and the holding time is 40min;

[0041] (4) First degrease th...

Embodiment 2

[0047] The preparation method of powder metallurgy wear-resistant stainless steel in this embodiment comprises the following steps:

[0048] (1) Mix 100-mesh 434L stainless steel powder with an organic lubricant to obtain a mixed powder. In terms of weight percentage, the content of the organic lubricant in the mixed powder is 0.3wt%, and the content of unavoidable impurities is no more than 2wt%;

[0049] (2) Put the mixed powder obtained in step (1) in a mold, press with a warm mold, the temperature of the female mold is 120°C, and form a powder metallurgy green body. The density of the green body after forming is 6.60g / cm 3 ;

[0050] (3) Place the powder metallurgy green body obtained in step (2) in a vacuum furnace and sinter under the protection of a high-purity nitrogen atmosphere with a pressure of 10KPa. The sintering temperature is 1150°C, the holding time is 40min, and the sintering density is 7.00g / cm 3 ;

[0051] (4) First degrease the surface of the sintered ...

Embodiment 3

[0055] The preparation method of powder metallurgy wear-resistant stainless steel in this embodiment comprises the following steps:

[0056] (1) Mix 100-mesh 316L stainless steel powder with an organic lubricant to obtain a mixed powder. In terms of weight percentage, the content of the organic lubricant in the mixed powder is 0.8wt%, and the content of unavoidable impurities is no more than 2wt%;

[0057] (2) Put the mixed powder obtained in step (1) in a mold, press with a warm mold, and the temperature of the female mold is 120°C, and form it to obtain a powder metallurgy green body. The green body density after forming is 6.50g / cm 3 ;

[0058] (3) The powder metallurgy green body obtained in step (2) is placed in a push rod furnace, and the volume ratio is 1:1 of H 2 with N 2 Sintering is carried out under the protection of a mixed atmosphere, the sintering temperature is 1280°C, the holding time is 35min, and the sintering density is 6.70g / cm 3 ;

[0059] (4) First de...

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Abstract

The invention relates to a preparation method for powder metallurgy wear-resisting stainless steel. The preparation method sequentially includes the following steps of mixed powder preparation, die forming, high-temperature sintering and nitriding treatment. According to the preparation method, a gas nitriding treatment mode is adopted, mixed gas of NH3 and N2 are used for nitriding treatment, and cost is greatly lowered compared with high-nitrogen stainless steel powder prepared in the prior art. Besides, two-stage nitriding is adopted in the preparation method, nitrides with high dispersity are formed on the surface of a workpiece under the conditions of a low nitriding temperature and a high ammonia content, and then surface nitrogen atoms are diffused inwards under the conditions of a high nitriding temperature and a low ammonia content, so that the thickness of a nitride layer is increased. The nitrogen content of the stainless steel prepared according to the method is 0.2-1.0 wt%, the apparent hardness HRC of the stainless steel is equal to or larger than 20, and the nitrogen content and the hardness of the stainless steel are increased effectively.

Description

technical field [0001] The invention relates to a preparation method of powder metallurgy wear-resistant stainless steel. Background technique [0002] Since the 1970s, due to the rapid development of pre-alloyed powders prepared by atomization, it has become possible to prepare high-performance sintered stainless steel. The production of stainless steel by powder metallurgy overcomes the shortcomings of traditional smelting technology, such as high production cost, low utilization rate of metal materials, and low dimensional accuracy of products. Powder metallurgy stainless steel is mainly 300 series and 400 series stainless steel. These two types of stainless steel have good corrosion resistance and plasticity, but poor wear resistance. [0003] Adding nitrogen to stainless steel can significantly improve the strength and wear resistance of the material. In addition to partially replacing precious nickel, the role of nitrogen is mainly to improve the strength of stainles...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C33/02C23C8/26C21D6/00C21D1/773
Inventor 周国燕包崇玺潘中晨
Owner NBTM NEW MATERIALS GRP
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