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Process method for improving surface quality of quenched-and-tempered steel nitrided members

A technology of surface quality and process method, applied in the direction of metal material coating process, coating, solid-state diffusion coating, etc., can solve the problems of low hardness, porosity or brittleness, etc., to improve wear resistance, avoid accumulation, and improve corrosion resistance sexual effect

Active Publication Date: 2019-01-22
CHANGZHOU TIANSHAN HEAVY IND MACHINERY
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Problems solved by technology

[0004] The purpose of the present invention is to provide a process for improving the surface quality of quenched and tempered steel nitrided parts, so as to solve the quality problems of 42CrMo quenched and tempered steel in the prior art that are prone to low hardness, looseness or brittleness after gas nitriding

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  • Process method for improving surface quality of quenched-and-tempered steel nitrided members
  • Process method for improving surface quality of quenched-and-tempered steel nitrided members

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Embodiment

[0016] A process method for improving the surface quality of quenched and tempered steel nitriding parts adopts a pre-oxidation three-stage rapid nitriding process, specifically including three stages of hard nitriding strong infiltration, diffusion, and nitrogen supplementation. Among them, pre-oxidize for 1-2 hours before the strong infiltration stage, and the temperature is 350-450°C. In the strong infiltration stage, the temperature is 490-520°C, the time is 15 hours, and the decomposition rate of ammonia gas is 18-25%. The temperature in the diffusion stage is 550-570° C., the time is 25 hours, and the decomposition rate of ammonia gas is 50-60%. Adjust the temperature of the nitrogen supplementation stage to 490-500° C., the time is 5 hours, and the ammonia gas decomposition rate is 45-50%.

[0017] In order to highlight the beneficial effects of the process of the present invention, the following comparative experiments were also carried out, see Table 1 for details. ...

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Abstract

The invention relates to the technical field of heat treatment processes and particularly relates to a process method for improving surface quality of quenched-and-tempered steel nitrided members. Themethod specifically adopts a preoxidation three-stage-process rapid nitriding process and comprises three stages, i.e., rigid-nitriding intense nitriding, diffusion and adjusting nitrogen feeding. Intense nitriding is carried out in a nitriding environment with low ammonia gas decomposition rate, so that the nitrogen concentration of workpiece surfaces is increased; diffusion is carried out in anitriding environment with high ammonia gas decomposition rate, so that the accumulation of surface nitrides is avoided; the rate and temperature of decomposition of ammonia gas are lowered, and the nitrogen concentration of the workpiece surfaces is adjusted. Through an improvement on a nitriding process, the surface hardness of workpieces is improved to 650HV1 to 680HV1, the surface brittlenessis a level 2 or less, and 80% or more of results display that the surfaces of the workpieces are free of obvious brittle cracks.

Description

technical field [0001] The invention relates to the field of heat treatment technology, and the specific field is a process method for improving the surface quality of quenched and tempered steel nitrided parts. Background technique [0002] Gas nitriding is a metal heat treatment process that puts metal materials in a certain medium and changes the chemical composition and metallographic structure of the material surface through the five basic processes of atmosphere formation, adsorption, decomposition, absorption and diffusion to control its performance. . Metal heat treatment is an important part of the machinery manufacturing industry. [0003] Carburized parts mainly include shafts and ring gears, which are the basic workpieces in mechanical transmission, and their performance and life directly affect the quality index and operation of the whole machine. With the vigorous development of the wind power industry, more and more wind power ring gears are made of quenched...

Claims

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Application Information

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IPC IPC(8): C23C8/26
CPCC23C8/26
Inventor 张林建王昱程牟杏华
Owner CHANGZHOU TIANSHAN HEAVY IND MACHINERY
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