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Surface strengthening heat treatment method capable of improving hardness gradient

A heat treatment method and surface strengthening technology, applied in the field of heat treatment, can solve the problems of parts performance decline, insufficient surface hardness of workpiece, insufficient hardness, etc., to improve surface hardness and hardness gradient, shorten diffusion time and total time, and reduce residual austenite. body mass effect

Inactive Publication Date: 2018-06-05
NANJING INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] 1. The carbon potential is low in the carburizing stage, the carbon content in austenite is low, and the carbon concentration gradient is low. After heat treatment, the surface hardness of the workpiece is insufficient, and the hardness gradient is low, and the depth of the standard hardness value is too shallow. The common problem is the inspection of the workpiece after heat treatment The surface hardness is qualified, but after subsequent surface machining, the hardness is insufficient and the wear resistance is poor;
[0006] 2. The temperature in the overall carburizing stage is constant. Simply increasing the carbon potential in order to increase the hardness after heat treatment will easily lead to the formation of large block or network carbides, which will seriously reduce the performance of the parts;
[0007] 3. The carburizing treatment temperature is constant, the production cycle is long, the production efficiency is low, and the cost is high

Method used

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  • Surface strengthening heat treatment method capable of improving hardness gradient
  • Surface strengthening heat treatment method capable of improving hardness gradient
  • Surface strengthening heat treatment method capable of improving hardness gradient

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Effect test

Embodiment 1

[0033] A surface strengthening heat treatment method capable of increasing the hardness gradient, comprising the following steps:

[0034] S01. Segmented heating and uniform temperature, place the parts in the heating furnace and heat to 640°C, keep warm for 2-3h, continue to heat to 840°C, keep warm for 2h;

[0035] S02. High carbon potential and strong infiltration. The parts continue to be heated to 910°C with the heating furnace, and the carburizing agent is passed into the heating furnace for carburization. The carbon potential CP is controlled at 1.05C%, and the carburizing time is 10h;

[0036] S03. Increase the temperature diffusion. After the step S02 is completed, increase the temperature of the heating furnace to 920° C., and reduce the carbon potential CP to 0.75C% to enter the diffusion stage, and the diffusion time is 3 hours;

[0037] S04. Segmented cooling and uniform temperature. After step S03 is completed, reduce the temperature of the heating furnace, and t...

Embodiment 2

[0043] A surface strengthening heat treatment method capable of increasing the hardness gradient, comprising the following steps:

[0044] S01. Segmented heating and uniform temperature, place the parts in the heating furnace and heat to 650°C, keep warm for 2.5h, continue to heat to 850°C, keep warm for 2.5h;

[0045] S02. High carbon potential and strong infiltration. The parts continue to be heated to 930°C with the heating furnace, and the carburizing agent is passed into the heating furnace for carburization. The carbon potential CP is controlled at 1.15C%, and the carburizing time is 20h;

[0046] S03. Increase the temperature diffusion. After step S02 is completed, increase the temperature of the heating furnace to 940° C., and reduce the carbon potential CP to 0.85C% to enter the diffusion stage, and the diffusion time is 5 hours;

[0047] S04. Segmented temperature reduction and uniform temperature. After step S03 is completed, reduce the temperature of the heating fu...

Embodiment 3

[0053] A surface strengthening heat treatment method capable of increasing the hardness gradient, comprising the following steps:

[0054] S01. Segmented heating and uniform temperature, place the parts in the heating furnace and heat to 660°C, keep warm for 3h, continue heating to 860°C, keep warm for 3h;

[0055] S02. High carbon potential and strong infiltration. The parts continue to be heated to 950°C with the heating furnace, and the carburizing agent is passed into the heating furnace for carburization. The carbon potential CP is controlled at 1.30C%, and the carburizing time is 30h;

[0056] S03. Increase the temperature diffusion. After step S02 is completed, increase the temperature of the heating furnace to 960° C., and reduce the carbon potential CP to 1.00C% to enter the diffusion stage, and the diffusion time is 8 hours;

[0057] S04. Segmented cooling and uniform temperature. After step S03 is completed, reduce the temperature of the heating furnace, and the par...

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Abstract

The invention discloses a surface strengthening heat treatment method capable of improving hardness gradient. The surface strengthening heat treatment method comprises the following steps: sectional warming and temperature equilibrium, high carbon potential strong permeability, temperature diffusion improvement, sectional cooling and temperature equilibrium, high-temperature tempering, quenching and low-temperature tempering. According to the surface strengthening heat treatment method provided by the invention, the surface hardness and abrasive resistance of parts can be improved, the hardness gradient is improved, the up-to-standard hardness depth is increased, fine granular carbides with dispersed distribution are obtained, the comprehensive mechanical property of parts is promoted, theheat treatment time is shortened, the production efficiency is improved, and the energy consumption is reduced.

Description

technical field [0001] The invention belongs to the technical field of heat treatment, in particular to a surface strengthening heat treatment method capable of increasing hardness gradient. Background technique [0002] There are many ways to strengthen the surface of metal materials. Among them, carburizing and quenching is a common heat treatment process for metal materials. It can make the surface of carburized workpieces obtain high hardness, wear resistance and contact fatigue strength. At the same time, the carbon concentration in the core of the workpiece remains unchanged, maintaining good toughness. In addition, due to the difference in martensite transformation and carbon content between the surface layer and the core, favorable residual compressive stress will be formed on the surface layer to improve the bending fatigue strength of the steel. Many important parts in mechanical mechanisms that require high hardness and wear resistance, especially steel parts and...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C8/22C21D1/18
CPCC23C8/22C21D1/18C21D2211/008
Inventor 丛园巨佳王章忠张保森朱帅帅戴玉明
Owner NANJING INST OF TECH
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