Microstructure and Properties of 980MPa Ultrafine-grained Cold Rolled Dual-Phase Steels

摘要：

Two kinds of 980MPa grade cold rolled dual phase steels have been developed by designing C-Si-Mn and C-Si-Mn-Nb alloy systems. The microstructure of martensite in Nb-free steel is consisted of lath martensite and twined martensite with the volume fraction of 67％. However, the main hard phase in Nb-containing one is twined martensit with the volume percent of 59％. The size of martensite islands in Nb-containing steel is from 1μm to 3μm, and the size of NbC precipitates is from 15nm to 40nm. As to Nb-containing steel, the yield strength, tensile strength, yield ratio and elongation are 501MPa, 1035MPa, 0.48 and 17.5％ respectively. Futhermore, Nb-containing steel has higher working hardening rate value above the critical strain 6.5％. And it decreases slowly with increasing the strain. This is mainly because of ultrafine grain size and nano-precipitates in ferrite, which improves the compatibility of phases and reduces the stress concentration at the phase interface.

关键词： ultra-high-strength dual-phase steel ultra-fine grain microstructure properties

作者: HAN Qi-hang KANG Yong-lin ZHAO Xian-meng

作者单位: School of Materials Science and Engineering, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China

会议类型: 国际会议

会议名称: The 6th International Conference on High Strength Low Alloy Steels(第六届高强度低合金钢国际会议HSLA Steels2011)

会议地点: 北京

会议语种:英文

页码: 731-735

在线出版日期: 2011-05-31（万方平台首次上网日期，不代表论文的发表时间）