摘要
采用低温奥氏体预变形+等温贝氏体相变相结合的工艺,研究了变形对中碳贝氏体钢相变和组织的影响,利用热模拟实验、SEM、TEM、XRD和拉伸实验等分析了变形影响残余奥氏体的微观机理及其对强塑性的影响规律。结果表明,过冷奥氏体在300℃变形20%,不仅可以加速随后等温贝氏体相变,细化贝氏体组织,同时还能增加室温组织中的残余奥氏体及其稳定性。残余奥氏体稳定性同时受C含量和位错密度影响,延长等温时间可以增加奥氏体中C含量;变形可以使奥氏体中位错密度增加,有利于获得稳定性较高的残余奥氏体,从而优化超高强贝氏体钢综合性能,制备的中碳超高强贝氏体钢抗拉强度为1733 MPa,延伸率达到15.7%。
Ultra-high-strength bainitic steels with excellent combinations of strength and ductility may be the new generation of metallurgical interest. However, there still exist some production problems,such as long transformation times due to low-temperature processing and difficulty in tailoring the elongation. In this work, both ausforming and austempering were used to investigate the effects of deformation on the transformation and microstructure in a medium-carbon bainitic steel. The Gleeble 3500 simulator,SEM, TEM, XRD, and tensile tests were used to analyze the effects of ausforming on retained austenite,the strength and plasticity of bainitic steel. The results show that ausforming at 300 ℃ with a strain of 0.2 not only accelerates the kinetics of isothermal transformation, but also refines the bainitic microstructure and optimizes the retained austenite and its stability. The stability of the retained austenite is affected by the carbon content and dislocation density, and the carbon content can be increased by prolonging the duration of the isothermal stage. The volume fraction of retained austenite is increased by ausforming because of the enhanced dislocation density, which leads to ultra-high-strength bainitic steel with excellent properties of a tensile strength of 1733 MPa and ductility of 15.7%.
作者
刘曼
胡海江
田俊羽
徐光
LIU Man;HU Haijiang;TIAN Junyu;XU Guang(State Key Laboratory of Refractories and Metallurgy,Wuhan University of Science and Technology,Wuhan 430081,China;Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education,Wuhan University of Science and Technology,Wuhan 430081,China)
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2021年第6期749-756,共8页
Acta Metallurgica Sinica
基金
国家自然科学基金项目Nos.51704217、51874216和51274154
湖北省技术创新专项重大项目No.2017AAA116。
