22CrMoH钢预先热处理与渗碳工艺

工程硕士学位论文

22CrMoH钢

预先热处理与渗碳工艺研究及其应用

STUDY ON PREHEAT-TREATMENT AND CARBURIZING PROCESSES OF 22CrMoH STEEL AND ITS APPLYCATION

管金玲

2012年3月

国内图书分类号：TG142.1

国际图书分类号：620

工程硕士学位论文

22CrMoH钢

预先热处理与渗碳工艺研究及其应用

硕士研究生：管金玲

导师：闫牧夫教授

申请学位：工程硕士

学科：材料工程

所在单位：哈尔滨一汽变速箱股份

有限公司

答辩日期：2012年3月

授予学位单位：哈尔滨工业大学

Classified Index: TG142.1

U.D.C.: 620

Dissertation for the Master Degree in Engineering

STUDY ON PREHEAT-TREATMENT AND CARBURIZING PROCESSES OF 22CrMoH STEEL

AND ITS APPLYCATION

Candidate：Guan jinling

Supervisor：Prof.Yan Mufu

Academic Degree Applied for：Master of Engineering Speciality：Materials Science

Affiliation：Harbin Faw Gear Box Co.,Ltd Date of Defence：March, 2012

Degree-Conferring-Institution：Harbin Institute of Technology

哈尔滨工业大学工程硕士学位论文

摘要

本文研究了主要用于后桥主从动圆锥齿轮的22CrMoH材料的热处理工艺，包括预先热处理和最终热处理两部分。预先热处理采用等温正火，研究了奥氏体化温度和等温温度对组织和性能的影响；还研究了渗碳热处理时不同工艺参数对渗碳层显微组织和硬度的影响，优化了热处理工艺参数，并通过变性试验，磨削试验和疲劳寿命试验，验证优化的工艺参数的可靠性。

22CrMoH材料渗碳钢，由于合金元素作用，普通正火无法完成预先热处理要求的组织转变，应采用等温正火。试验在实验阶段进行，采用920℃，930℃，940℃三个奥氏体化温度，640℃，660℃，680℃三个等温温度，进行等温正火，确定940℃加热奥氏体化后，空冷至670℃等温，然后出炉空冷的等温正火工艺，并经生产实际应用验证了该工艺能获得良好的显微组织和硬度，并对减小热处理淬火变形有一定作用。

20CrMoH材料的渗碳，应采用二段式，本文按920℃、930℃二个渗碳温度，1.1%、1.15%和1.2%三个强渗碳势和0.7%、0.8%、0.85%三个扩散碳势，制定了16个试验工艺，然后分别200℃、220℃回火，通过不同工艺对试样的有效硬化层、显微组织、表面硬度、心部硬度以及碳浓度分布和渗碳层硬度分布的影响规律。确定了优化的热处理渗碳工艺参数为：渗碳温度920℃，强渗碳势1.15，扩散碳势0.80%，220℃回火。

在变形量控制要求不高的情况下，930℃渗碳，金相组织优于920℃，节约渗碳时间0.5小时以上，具有可观的经济效益。

关键词 22CrMoH；等温正火；渗碳；回火

- I -

哈尔滨工业大学工程硕士学位论文

- II -

Abstract

22CrMoH steel was widely used in rear axle of automobile. The heat-treatment processes of 22CrMoH steel were investigated, including the pre-treatment and the final heat-treatment, in the present study. Isothermal normalizing will be introduced as pre-treatment. Both ffects of austenitizing temperature and isothermal temperature on the microstructure and properties and the effects of carburizing parameters on the micro morphology of carburizing layer and hardness distribution were discussed in order to determine better heat-treatment parameters. Finally, the best heat-treatment parameters were verified by the test of distortion, grinding and fatigue life.

22CrMoH carburized steel, as the result of the alloy elements, ordinary normalizing couldn't complete normalizing microstructure transformation, so it must adopt the isothermal normalizing process. Simulation test was carried out in the laboratory, using three austenitizing temperature, 920℃、930℃、940℃, three isothermal temperature,640℃、660℃、680℃ to carry out isothermal normalization and identify the isothermal normalizing process which was heated to austenitizing temperature of 940, air cooled to 670, ℃℃holding a definite time and air cooled to room temperature. In contrast to the actual production process, it could achieve the excellent microstructure and microhardness, it also could reduce hot deformation. Carburizing in 20CrMoH steel should adopt two stage method. According to two carburization temperature, 920℃、930, three ℃strong permeably carbon potential, 1.1%、1.15%、1.2%, three diffused carbon potential, 0.7%、0.8%、0.85%, it reassured 16 process testings, and tempering experiments were carried out on two different tempering temperature (200℃、220℃). Through researching the influence of different technologies on the available hardened depth, microstructure, surface hardness, core hardness, distribution of carbon concentration and carburizing layer hardness, the optimum craft parameters was determined. The carburization temperature was 920 , ℃strong permeably carbon potential was 1.15%, diffused carbon potential was 0.80% and tempering temperature was 220. ℃