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Stainless steel powder metallurgy material preparation method

A technology of powder metallurgy and stainless steel powder, which is applied in the field of powder metallurgy material preparation and can solve problems such as poor formability, low carbon content, and difficult process control

Inactive Publication Date: 2009-12-09
GUANGZHOU RES INST OF NON FERROUS METALS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The commonly used grades of powder metallurgy high-hardness stainless steel are 410, Cr12 or 440C series. The Cr12 series has low carbon content, good process performance, easy to form, wide sintering temperature range, easy to control, but low hardness, which cannot be used alone. Required hardness HRC≥45 requirements
Although the 440C series powder can finally reach the required hardness, the formability is poor, the sintering temperature range is narrow, and the process control is difficult, especially when making parts with complex shapes, the dimensional accuracy is difficult to guarantee

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0010] By weight percentage (the same below), Cr12 stainless steel powder 68.25%, 440C stainless steel powder 30%, graphite powder 1.0%, lithium stearate 0.75%, after being uniformly mixed, press molding on the hydraulic press, the green compact density is 5.7g / cm 3 . Sinter in a vacuum sintering furnace at a temperature of 1280°C, a vacuum of 5-20Pa, and a holding time of 90 minutes; cool down to 1050°C, fill it with nitrogen to cool to room temperature, and leave the furnace. Place it in a mesh belt type continuous heat treatment furnace for heat treatment at a temperature of 1060°C, hold for 30 minutes, and fill it with nitrogen to cool. The measured hardness of the stainless steel powder metallurgy material: HRC 52~54, density: 7.60g / cm 3 , relative density: 99%. The powder metallurgy material is suitable for making meat grinder blades.

Embodiment 2

[0012] 83.55% of Cr12 stainless steel powder, 15% of 440C stainless steel powder, 0.70% of graphite powder, 0.75% of zinc stearate, uniformly mixed and pressed on a hydraulic press, the compact density is 6.1g / cm 3 . Sinter in a vacuum sintering furnace at a temperature of 1265°C, a vacuum of 10Pa, and a holding time of 90 minutes; cool to 1000°C, fill with nitrogen and cool to room temperature, and then come out of the furnace. Put it into a mesh-belt type continuous heat treatment furnace for heat treatment at a temperature of 1020°C, hold for 30 minutes, and fill it with nitrogen to cool. Measured hardness: HRC 48~50, density: 7.45g / cm 3 , relative density: 97%. The powder metallurgy material is suitable for making peanut knife grinding discs.

Embodiment 3

[0014] 88.55% of Cr12 stainless steel powder, 10% of 440C stainless steel powder, 0.70% of graphite powder, and 0.75% of zinc stearate. The raw materials are uniformly mixed and pressed on a hydraulic press. The compact density is 5.9g / cm 3 . Sinter in a vacuum sintering furnace at a temperature of 1260°C, a vacuum of 8 Pa, and a holding time of 90 minutes; cool to 950°C, fill with nitrogen and cool to room temperature, and leave the furnace. Place it in a mesh belt type continuous heat treatment furnace for heat treatment at a temperature of 980°C and a holding time of 40 minutes, then fill it with nitrogen to cool. Measured hardness: HRC 45~48, density: 7.40g / cm 3 , relative density: 96%. The powder metallurgy material is suitable for making coffee machine cutter heads.

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Abstract

A stainless steel powder metallurgy material preparation method is characterized by mixing 68.25-88.55wt% of Cr12 stainless steel powder, 10-30wt% of 440C stainless steel powder, 0.6-1.0wt% of graphite powder and 0.75-1.0wt% of stearate, pressurizing to ensure that the pressed green density is 5.8-6.2g / cm; sintering the material for 90-120min at 1260-1290 DEG C and at 5-20Pa, lowering the temperature to 950-1050 DEG C, then injecting nitrogen for cooling; reheating to 980-1060 DEG C and preserving the temperature for 30-45min and injecting nitrogen for cooling. The invention is a stainless steel powder metallurgy material preparation method with good formability and controllable sintering process which can meet the demands of the hardness and density. The method of the invention is applicable to preparing stainless steel products, beverage machinery and the like.

Description

technical field [0001] The invention relates to a preparation method of a powder metallurgy material, in particular to a preparation method of a stainless steel powder metallurgy material. Background technique [0002] The wide application of high-hardness stainless steel in food and beverage machinery is gradually replacing the ordinary carbon alloy steel in the past. Because the requirements for material properties in this field are not very high, and the food industry has a high demand for processing and machinery. Contamination requirements for food and beverages are very high. Therefore, more and more application fields are being replaced by high-hardness stainless steel, such as meat grinder blades, cutter heads, coffee machine cutter heads, peanut butter grinder cutter heads, etc. What this kind of machinery has in common is that the working medium contains a certain amount of grease. Although the corrosion resistance of high-hardness stainless steel cannot be compar...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C33/02
Inventor 陈强蔡一湘罗锴李丹丹
Owner GUANGZHOU RES INST OF NON FERROUS METALS
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