摘要：研究了45钢不同亚温淬火工艺参数对组织的影响。通过控制亚温淬火温度以及保温时间这两个参数来研究45钢组织以及性能的影响。对45钢亚温淬火试样进行金相组织观察以及硬度测量。结果表明，在亚温淬火温度750℃~780℃的范围，铁素体组织含量减少，从大块状到网状。马氏体组织含量增加并且其形态也发生改变，从板条状组织到细针状组织。其硬度和强度也随着温度的上升而增加。随着保温时间的增加，其硬度也随之增加。相比较常规淬火840℃，亚温淬火组织晶粒度更细。淬火温度780℃保温时间30min的效果最佳，细针状马氏体以及微量呈网状均匀分布的铁素体，具有良好的强韧配合。62121

毕业论文关键词： 45钢；亚温淬火；组织；硬度

Effects of Subcritical Quenching Processing Parameter on Microstructure of 45 Steel

Abstract: Study of the effects of different subcritical quenching process parameters on the quenching microstructure of 45 steel. By controlling subcritical quenching temperature and holding time to study the effect of these two parameters on microstructure and property of 45 Steel. Doing microstructure observation and hardness measurement on subcritical quenching sample of 45 steel. The results showed that in the range of subcritical quenching temperature of 750℃~780℃, the ferrite content decreased, from the big block to the mesh. Martensitic structure content has also been decreased and its shape is changed, from lath-like microstructure to fine acicular structure. Hardness and strength also increase with the rise of temperature. With the increase of holding time, the hardness of 45 steel increases. Compared with conventional quenching on 840℃, subcritical quenching structure has a finer grain size. Quenching temperature of 780℃ and holding time of 30 min gave best results, fine acicular martensite and netlike ferrite evenly distributed, and with good match of strength and temper.

KeyWords： 45 steel；subcritical quenching；microstructure；hardness 

目  录

1  绪论 1

1.1  45钢介绍 1

1.2  淬火热处理工艺 2

1.2.1  淬火介质 3

1.2.2  淬火温度 4

1.2.3  保温时间 5

1.2.4  淬透性 6

1.3  常用淬火工艺 7

1.4  淬火新工艺 8

1.5  亚温淬火工艺 8

1.6  课题的研究现状 10

1.7  选题的意义 10

2  实验材料及实验方法 12

2.1  实验材料 12

2.2  淬火热处理工艺制定 13

2.2.1  淬火温度 13

2.2.2  保温时间 13

2.2.3  冷却方式 13

2.3  淬火热处理 14

2.4  金相组织观察 15

2.4.1  金相制样 15

2.4.2  组织观察 16

2.5  硬度测量 17

3  实验结果及分析 19

3.1  金相组织及分析