摘要
为解决含Cu中碳低合金钢在高温回火过程中强度与韧性难匹配的问题,设计了一种可协调强韧性的新型热处理方案.采用力学性能测试、组织表征、热力学计算等方法研究了多步热处理对实验钢微观组织及力学性能的影响.结果表明:通过淬火—亚临界退火—临界回火—回火多步热处理后获得了回火马氏体+临界铁素体混合组织,马氏体板条变窄、组织得到细化、大角度晶界增加、位于原奥氏体晶界和板条界处的片状渗碳体球化,且板条内有部分富Cu相粗化.在该工艺下可获得优异的综合力学性能,屈服强度为901 MPa,抗拉强度为1003 MPa,延伸率为22%,冲击功为35 J.与传统淬火—回火工艺相比,该工艺下实验钢的强度降低,但冲击韧性提高约3倍,延伸率提高约50%.
To solve the problem that the strength and toughness of Cu-bearing medium carbon low alloy steel are difficult to coordinate during high temperature tempering,a novel multi-step heat treatment scheme was designed.The effects of the heat treatment on the microstructure and mechanical properties of the experimental steel were investigated by mechanical properties test,microstructure characterization and thermodynamic calculation.The results show that after quenching-subcritical annealing-inter-critical tempering-tempering,the mixed microstructure with tempered martensite and inter-critical ferrite is obtained.The martensite lath becomes narrower,the microstructure is significantly refined,high angle grain boundaries increase,the lamellar cementite distributed at the prior austenite grain boundaries and lath boundaries is spheroidized,partial Cu-rich phases in the lath are coarsened.Excellent comprehensive mechanical properties can be obtained by the multi-step process,with yield strength of 901 MPa,tensile strength of 1003 MPa,elongation of 22%and impact energy of 35 J.Compared to that after traditional quenching-tempering process,the strength of experimental steel is reduced,but the impact toughness and elongation are increased by around 3 times and 50%respectively.
作者
邸洪双
柯浩鹏
张天宇
DI Hong-shuang;KE Hao-peng;ZHANG Tian-yu(State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,China)
出处
《东北大学学报(自然科学版)》
EI
CAS
CSCD
北大核心
2023年第3期340-347,356,共9页
Journal of Northeastern University(Natural Science)
基金
“十三五”国家重点研发计划项目(2018YFB1308704)
国家自然科学基金资助项目(51775102).
关键词
含Cu中碳钢
多步热处理
析出
热力学计算
力学性能
Cu-bearing medium carbon steel
multi-step heat treatment
precipitation
thermodynamic calculation
mechanical properties