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Heating treatment technology for piston pin

A piston pin and process technology, which is applied in heat treatment furnaces, heat treatment equipment, metal material coating processes, etc., can solve problems such as difficult to control the stability of the piston pin size, and achieve the effect of good product size and convenient production process

Inactive Publication Date: 2016-01-13
SINO TRUK JINAN POWER
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In order to reduce the content of retained austenite, on the premise of ensuring the quality of raw materials is stable, it is usually used to reduce the quenching temperature, control the surface carbon content after carburizing, or increase the tempering temperature, etc., so it is difficult to control the stability of the size of the piston pin

Method used

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  • Heating treatment technology for piston pin
  • Heating treatment technology for piston pin
  • Heating treatment technology for piston pin

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Carburizing and quenching: After the piston pin is carburized, it is quenched at a temperature of 820±10°C, and the temperature of the quenching oil is 40-60°C;

[0021] Cryogenic treatment: put the piston pin after carburizing and quenching into -120°C liquid nitrogen for 60 minutes;

[0022] Tempering: In order to reduce the structural stress after the martensite transformation is completed, the piston pin needs to be tempered at a temperature of 180°C for 90min-120min and air-cooled.

[0023] Depend on figure 2 It can be seen that when cryogenic treatment is carried out in liquid nitrogen at -120°C, the content of retained austenite is 13%; image 3 It can be seen that after heating and holding at 220°C for 4 hours, the corresponding outer diameter increases by 0.007mm.

Embodiment 2

[0025] Carburizing and quenching, the piston pin is quenched at a temperature of 820±10°C after carburizing, and the quenching oil temperature is 40-60°C;

[0026] Cryogenic treatment, put the piston pin after carburizing and quenching into -160°C liquid nitrogen for 60 minutes;

[0027] Tempering, in order to reduce the structural stress after the martensitic transformation is completed, the piston pin needs to be tempered at 200°C for 90min-120min and air-cooled.

[0028] Depend on figure 2 It can be seen that when cryogenic treatment is carried out in liquid nitrogen at -160°C, the retained austenite content is 8%; image 3 It can be seen that after heating and holding at 220°C for 4 hours, the corresponding outer diameter decreases by -0.0025mm.

Embodiment 3

[0030] Carburizing and quenching: After the piston pin is carburized, it is quenched at a temperature of 820±10°C, and the temperature of the quenching oil is 40-60°C;

[0031] Cryogenic treatment: put the piston pin after carburizing and quenching into -130°C liquid nitrogen for 60 minutes;

[0032] Tempering: In order to reduce the structural stress after the martensite transformation is completed, the piston pin needs to be tempered at a temperature of 180°C for 90min-120min and air-cooled.

[0033] Depend on figure 2 It can be seen that when cryogenic treatment is carried out in liquid nitrogen at -130°C, the retained austenite content is 12%; image 3 It can be seen that after heating and holding at 220°C for 4 hours, the corresponding outer diameter increases by 0.004mm.

[0034] In order to reduce the residual austenite content after carburizing and quenching, and prevent the residual austenite from transforming into martensite during the use of the piston pin to inc...

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Abstract

The invention discloses a heating treatment technology for a piston pin. The heating treatment technology includes the following steps: (1) carburizing and quenching, (2) subzero treatment and (3) tempering. In order to reduce the retained austenite content obtained after carburizing and quenching and prevent the phenomenon that retained austenite is converted into martensite in the using process of the piston pin, and consequently, the size of the piston pin is increased, on the premise that the quenching temperature is decreased, tempering is not carried out after quenching, and the piston pin directly enters liquid nitrogen for subzero treatment, so that the retained austenite content is reduced, the retained austenite is continuously converted into the martensite at the liquid nitrogen temperature, and the size is stable. Tests prove that the subzero temperature is controlled to range from -160 DEG C to -120 DEG C, and the retained austenite content ranges from 8% to 13%; and after heating at 220 DEG C is carried out and heat preservation is carried out for four hours, the corresponding outer diameter is increased by -0.0025 mm to 0.007 mm, the product size of the piston pin is better controlled, and the production process is convenient to control.

Description

technical field [0001] The invention relates to a heat treatment process, in particular to a heat treatment process aimed at improving the dimensional stability of a piston pin. Background technique [0002] The piston pin has a large load in the engine, poor lubrication conditions, uneven pressure distribution, etc. In order to ensure its reliable operation, there must be strict fit clearance and good friction surface quality. DIN73126 "Piston pin of reciprocating internal combustion engine - size, marking, material, specification, technical requirements" puts forward technical requirements for the increase of the outer diameter of the piston pin. Changes; after holding at 220°C for 4 hours, the piston pin with outer diameter d≤50mm has a maximum dimensional change of 0.006mm in the outer diameter direction, and the piston pin with outer diameter d>50mm has a maximum dimensional change in the outer diameter direction of 0.010mm. An important reason for the change in th...

Claims

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Application Information

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IPC IPC(8): C21D1/18C21D6/04C21D9/00C23C8/22
Inventor 鲁统轮马奎星李凤飞代瑞环
Owner SINO TRUK JINAN POWER