摘要:本论文研究了40Cr钢亚温淬火工艺参数对组织的影响。40Cr钢亚温淬火的温度在750℃~780℃之间，通过控制热处理淬火过程中加热温度以及保温时间这两个参数，对不同的实验结果进行分析。主要从金相组织及硬度这两个方面进行研究。实验结果表明：750℃亚温淬火状态下，试样的组织为铁素体和珠光体，保温10分钟时无明显马氏体出现，近似于原始组织，随加热温度的升高(765℃、780℃亚温淬火)、保温时间(20、30分钟)的增长，铁素体和珠光体组织减少，逐渐出现越来越多的马氏体组织，至珠光体全部消失，最终组织为大量马氏体及少量分散在马氏体周围的不规则小块状铁素体；在此过程中试样的硬度也随之增大。与840℃常规淬火比较，加热温度高于临界温度Ac3的常规淬火使试样的组织全部转变为马氏体，且硬度较大。57669

毕业论文关键词: 40Cr钢；热处理；亚温淬火；金相组织；硬度

Influence of intercritical quenching process parameters on the structure of 40Cr Steel

Abstract：This study is about the influence of quenching process parameters on the structure of 40 Cr Steel. Intercritical quenching of 40 Cr steel between 750℃ and 780℃,it was analyzed by the test result by controlling the heating temperature in the heat treatment quenching process and holding time of the two parameters. The study was mainly from two aspects of the metallographic structure and hardness. It was shown that: the microstructure of the test piece is ferrite and pearlite approximate to the original organization without obvious martensite though extending the time of heat preservation in 10 minutes. However, the ferrite and pearlite will decrease till disappear, and more and more martensite appear, at last there will be a large number of martensite and a small amount of ferrite around martensite while temperature is increasing(765℃,780℃ subcritical quenching) and heat preservation time is extending(20-30minutes); and the hardness of test piece is also increasing in the quenching process. Compared with the conventional quenching in 840℃, the test piece issue will change to martensite completely that the temperature is more than critical temperature Ac3, and it will also have a large hardness.

KeyWords：40Cr steel, heat treatment, intercritical quenching, microstructure, hardness

目  录

1绪论 1

1.1 40Cr简介 1

1.2 热处理淬火常规工艺 1

1.2.1 淬火加热方式 2

1.2.2 淬火加热温度 2

1.2.3 淬火保温时间 2

1.2.4 淬火冷却介质 3

1.2.5 淬火冷却方式 3

1.2.6 淬火硬度 4

1.3 热处理亚温淬火工艺 4

1.3.1 亚温淬火工艺基本概况 4

1.3.2 亚温淬火对力学性能的影响 4

1.3.3 亚温淬火对组织的影响 5

1.4 选题意义 5

2实验材料及实验方法 6

2.1 实验材料 6

2.1.1 40Cr钢的化学成分 6

2.1.2 40Cr钢的临界温度 6

2.1.3 试样尺寸 6

2.2 实验方法 7

2.2.1 原始样处理