两相区形变对中锰钢逆相奥氏体稳定性及其断裂性能的影响

Effect of intercritical deformation on reversed austenite stability of medium manganese steel and its fracture properties

采用D-ART(两相区形变-奥氏体逆相变)退火热处理工艺,研究不同两相区压缩量对试验钢组织演变、残留奥氏体含量与断裂性能的影响规律。结果表明:试验钢经两相区压缩退火后,获得铁素体、奥氏体与马氏体等多相组织,随压缩量由零增加到15%,残留奥氏体含量由15. 3%增加到23. 4%,其稳定性逐渐增强,C元素配分行为明显;对比未变形退火试样性能,压缩10%和15%的退火试样断后伸长率显著提高,分别达到35. 8%、42. 0%,强塑积最大值可达到35 490 MPa·%;压缩退火试样断口韧窝均匀,断裂性能得到有效改善。

The D-ART( intercritical deformation-austenite reversed transformation) annealing heat treatment process was applied to a lowcarbon medium-manganese steel to investigate the effects of intercritical compression amounts on microstructural evolution,retained austenite content and fracture properties.The results show that annealed experimental steel with different amounts of intercritical compression,the multi-phase microstructures obtained are composed by ferrite,austenite and martensite.The retained austenite content is gradually increased from 15.3% to 23.4% with the increase of compression amount from 0 to 15%,and its stability is gradually enhanced,the partition of carbon element becomes obvious.With compared with that of undeformed annealed samples,the elongation after fracture of the 10% and15%-compressed then annealed samples is significantly increased to 35.8% and 42.0% respectively,and the highest product of strength and elongation reaches 35 490 MPa ·%.The fractured dimples of the compressed then annealed samples are uniform and the fracture properties are effectively improved.