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Method for reducing heat treatment deformation of carburized and quenched part

A heat treatment deformation, carburizing and quenching technology, which is applied in heat treatment equipment, heat treatment process control, coating, etc., can solve the problems of large deformation, affecting the product consistency and reliability of carburized and quenched parts, and reduce forging stress and reduce Effect of uniform grinding cost and cooling rate

Inactive Publication Date: 2021-09-03
CRRC QISHUYAN INSTITUTE CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The main purpose of the present invention is to provide a method for reducing heat treatment deformation of carburized and quenched parts, so as to solve the problem that the carburized and quenched parts have large deformation after heat treatment in the existing manufacturing process, which will affect the consistency and quality of carburized and quenched parts. question of reliability

Method used

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  • Method for reducing heat treatment deformation of carburized and quenched part
  • Method for reducing heat treatment deformation of carburized and quenched part
  • Method for reducing heat treatment deformation of carburized and quenched part

Examples

Experimental program
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Effect test

Embodiment 1

[0038] Embodiment 1: 18CrNiMo7-6 ring gear, outer diameter 985mm, inner diameter 676mm, tooth width 81mm.

[0039] Preliminary heat treatment process: After the tooth blank is forged, heat the tooth blank to 880°C and keep it warm for 6 hours, then immerse it in a 73°C hot water cooling tank for cooling. The cooling time is determined by computer simulation technology, and the cooling time should ensure the surface temperature of the forging Not lower than the Ms point temperature, the forging core temperature is not lower than the Bs point temperature. After cooling, keep it in the heating furnace at 650°C for 8 hours and then air-cool.

[0040] Quenching and tempering heat treatment process: After the preparatory heat treatment, reheat the tooth blank to 940°C for 5 hours. Calculate the cooling medium evaluation value Q value, Q value is 165, choose 22 ℃ water. To this end, it was then immersed in a 25°C cooling water tank to cool down to room temperature, then reheated to...

Embodiment 2

[0047] Example 2: 20CrNi 3 Mo gear shaft, diameter 262mm, length 1979mm.

[0048] Preliminary heat treatment process: After the tooth blank is forged, reheat the tooth blank to 910°C for 6 hours, and then immerse it in a hot water cooling tank at 87°C for cooling. The cooling time is determined by computer simulation technology, and the cooling time should ensure that the surface temperature of the forging is not Below the Ms point temperature, the core temperature of the forging is not lower than the Bs point temperature. After cooling, keep it in the heating furnace at 670°C for 8 hours and then air-cool.

[0049] Quenching and tempering heat treatment process: After the preliminary heat treatment, reheat the tooth blank to 960°C for 5 hours. Calculate the Q value of the cooling medium evaluation value, the Q value is 313, choose 8.2% PAG quenching liquid of the AQ251 type produced by Houghton in the United States, and the medium temperature is 35 °C. To this end, it was ...

Embodiment 3

[0057] The difference from Example 1 is: the temperature of the first water cooling process is 100°C.

[0058] After carburizing and quenching, 20 ring gears were continuously measured for ellipticity, end face runout and top circle expansion and contraction data before and after carburizing and quenching, and the test results obtained by taking the average value are shown in Table 3.

[0059] table 3

[0060] Ovality,mm End runout, mm Expansion and shrinkage of top circle, mm 0.27 0.56 0.58

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Abstract

The invention provides a method for reducing heat treatment deformation of a carburized and quenched part. The method comprises the steps that a carburizing and quenching part blank is sequentially subjected to a preheating treatment process and a first air cooling process; and the carburizing and quenching part blank obtained through the first air cooling process is subjected to carburizing and quenching to obtain a carburizing and quenching part, a first water cooling process is further included between the preheat treatment process and the first air cooling process, the temperature of the first water cooling process is larger than or equal to 70 DEG C, the carburizing and quenching temperature T3 is higher than the preheat treatment temperature T1, and the temperature difference T is larger than or equal to 15 DEG C. The temperature of the first water cooling process and the temperature difference T between carburizing and quenching and pre-heat treatment are limited in the range, so that the uniformity of a steel structure in the carburizing and quenching part is improved, and the heat treatment deformation of the carburizing and quenching part is reduced. According to the method, the cost of building a production line, purchasing heat treatment tools and the like can be saved, the grinding cost is reduced, a carburized layer with good comprehensive performance is reserved, and the consistency and reliability of carburized and quenched parts are improved.

Description

technical field [0001] The invention relates to the field of manufacture of carburized and quenched parts, in particular to a method for reducing heat treatment deformation of carburized and quenched parts. Background technique [0002] In the manufacturing process of heavy-duty carburized and quenched parts (such as gears), to ensure the quality consistency and reliability of the product, one of the key points of control is to control its deformation during carburizing and quenching. There are many ways to realize the deformation control of carburizing and quenching parts in the process of carburizing and quenching, such as optimizing the structure, optimizing the carburizing and quenching process, using carburizing and quenching tooling (such as using a quenching press), etc. However, the heat treatment deformation control of carburizing and quenching is a systematic project, which requires the effective cooperation of various process links, especially the systematic coope...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D6/00C21D11/00C23C8/80
CPCC21D6/00C21D11/00C23C8/80
Inventor 文超董雯乔建勇高红梅宋倩
Owner CRRC QISHUYAN INSTITUTE CO LTD