摘要
采用理论分析和实验研究相结合的方法,对20CrMnMoH齿轮钢在预先热处理过程中产生贝氏体非平衡组织的现象进行了分析研究。结果表明:20CrMnMoH齿轮钢在常规预先热处理过程中的冷却速度无法控制,过冷奥氏体进行非平衡组织转变,容易得到贝氏体等非平衡组织。根据贝氏体等非平衡组织的组织遗传效应,结合过冷奥氏体等温转变的原理和机制,设计了两次等温正火预先热处理工艺,首次等温正火预先热处理完成了非平衡组织到平衡组织的转变,二次等温正火预先热处理实现了晶粒的细化和均匀化。通过工艺优化控制实现了齿轮锻件的金相组织为1~2级、同批次不同齿轮锻件硬度差≤5 HB的技术指标。成品齿轮的精度可以达到6级,验证了预先热处理对减小齿轮热处理畸变、提高齿轮精度的有效性。
The phenomenon of non-equilibrium microstructure for bainite produced in the pre-heat treatment process of gear steel 20CrMnMoH was analzed and studied by the method combining theoretical analysis and experimental research. The results show that the cooling rate of gear steel 20CrMnMoH in the conventional pre-heat treatment process cannot be controlled,and the undercooled austenite is easily transformed into bainite and other nonequilibrium structures. According to the structure genetic effects of bainite and other non-equilibrium microstructure,combining with the principle and mechanism of isothermal transformation for undercooled austenite,two times of preheat treatment process for isothermal normalizing were designed. Furthermore,the first pre-heat treatment of isothermal normalizing completes the transformation from the non-equilibrium microstructure to the equilibrium microstructure,and the second pre-heat treatment of isothermal normalizing realizes grain refinement and homogenization. Through the process optimization and control,the technical indicators of the metallographic structure of 1-2 grades for gear forgings and the hardness difference of different gear forgings in the same batch ≤5 HB are achieved. The accuracy of finished gear is detected up to level 6,which verifies the effectiveness of pre-heat treatment to reduce the heat treatment distortion of gear and improve the accuracy of gear.
作者
张义帅
孙红星
张超
刘光辉
刘忠明
郑晓华
刘华
Zhang Yishuai;Sun Hongxing;Zhang Chao;Liu Guanghui;Liu Zhongming;Zheng Xiaohua;Liu Hua(Zhengzhou Research Institute of Mechanical Engineering Co.,Ltd.,China Academy of Machinery Science and Technology,Zhengzhou 450001,China;School of Mechanical Engineering,Xi'an Jiaotong University,Xi'an 710049,China;School of Materials Science and Engineering,Taiyuan University of Science and Technology,Taiyuan 030024,China)
出处
《锻压技术》
CAS
CSCD
北大核心
2021年第3期184-191,共8页
Forging & Stamping Technology
基金
国家重点研发计划资助项目(2018YFB2001300)
郑州市重大科技专项(152PZDZX007)。
关键词
高性能齿轮
热处理畸变
预先热处理
组织转变
残余应力
high performance gear
heat treatment distortion
pre-heat treatment
microstructure transformation
residual stress
