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Metal material compound heat treatment surface strengthening method

A technology of composite heat treatment and surface strengthening, applied in the field of heat treatment, to achieve the effect of large thickness of the infiltrated layer, ensuring the strength and hardness of the infiltrated layer, and good strength and toughness

Active Publication Date: 2020-03-31
JIANGSU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the Q-P-T process is a process for metal body materials, and there is no precedent for surface strengthening alone

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] (1) 40Cr compound heat treatment surface strengthening. The 40Cr sample was cleaned by hot water, then air-dried and installed in the furnace. Ammonia, methanol and a little kerosene were introduced into the furnace. The flow rate of ammonia gas was 1m 3 / min, the kerosene flow rate is 50 drops / min, the methanol flow rate is 200 drops / min, and carbonitriding is carried out at 820°C for 2 hours;

[0025] (2) Lower the furnace temperature to 720°C, and the flow rate of ammonia gas in the furnace is 3m 3 / min, the flow rate of methanol is 100 drops / min, and nitrocarburizing is carried out for 1h.

[0026] (3) After the metal workpiece comes out of the furnace, immediately quench it in a nitrate solution at 280°C and keep it warm for 5 minutes.

[0027] (4) Carry out 160 ℃ of nitrate salt solutions and keep warm for 30min then;

[0028] (5) Finally, perform aging treatment at 230°C for 4 hours.

[0029] The hardness of the obtained infiltrated layer is greater than 720H...

Embodiment 2

[0031] (1) 08F steel composite heat treatment surface strengthening process. Thin flaky 08F steel samples were cleaned and air-dried and then installed in a furnace. Ammonia, methanol and a little kerosene were introduced into the furnace. The flow rate of ammonia gas was 1m 3 / min, the kerosene flow rate is 50 drops / min, the methanol flow rate is 200 drops / min, and carbonitriding is carried out at 840°C for 1h;

[0032] (2) Cool down to 700°C for nitrocarburizing, and the flow rate of ammonia gas in the furnace is 3m 3 / min, the flow rate of methanol is 100 drops / min, and nitrocarburizing is carried out for 2h. In the last 0.5h of nitrocarburizing, the flow rate of ammonia gas is reduced to 0.5m 3 / min, in order to achieve the purpose of removing the compound layer.

[0033] (3) After being released from the furnace, the metal workpiece is subjected to 280 ° C nitrate isothermal quenching and kept for 5 minutes;

[0034] (4) Then carry out nitrate isothermal 30min at 160°...

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Abstract

The invention belongs to the technical field of heat treatment and discloses a metal material compound heat treatment surface strengthening method. The method comprises the steps that a metal workpiece is heated to 780-900 DEG C, is subjected to carbonitriding by a certain depth and then is cooled to 650-720 DEG C and then is subjected to carbonitriding; during the later period of the carbonitriding process, a brittle compound layer in a nitriding layer is eliminated through control over a nitrogen potential; quenching is conducted, the workpiece is put into a nitrate solution of 250-300 DEG C to be subjected to isothermal quenching and heat preservation, then subjected to isothermal quenching at 120-180 DEG C and heat preservation and finally subjected to aging treatment at 220-240 DEG C. According to the method, the quenching temperature is low, deformation of metal parts is little, and the thickness of the nitriding layer is large; moreover, the surface of a non-brittle white bright layer can be obtained, and the brittleness of the nitriding layer is greatly reduced; meanwhile, after the quenching-distribution-tempering treatment, the strength and toughness of the core of a material is improved, and the strength and hardness of the nitriding layer are further improved. Besides, the metal workpiece is subjected to quenching twice, residual pressure stress is formed on the surface layer, and the anti-fatigue performance of the metal workpiece is improved.

Description

technical field [0001] The invention belongs to the technical field of heat treatment, and relates to a heat treatment process for metal material components, in particular to an effective method for strengthening the surface of medium-low carbon (low alloy) steel. Background technique [0002] As a mature chemical heat treatment process, nitriding and carburizing have been widely used in industrial production, especially for gears, shafts, thin sheets and other metal workpieces that require high surface strength and good toughness. However, the quenching heating temperature of the ordinary carburizing process is about 930°C, resulting in high quenching stress, and it is difficult to control the deformation of small and thin metal workpieces. Although the nitriding and austenitic nitrocarburizing process makes the quenching temperature below 700°C, the carburized layer is thin and brittle, which affects the surface strengthening effect. Therefore, it is of great industrial v...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23C8/32C21D1/20
CPCC21D1/20C21D2211/008C23C8/32
Inventor 熊志高袁志钟
Owner JIANGSU UNIV
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