调质处理对低碳微合金钢组织与力学性能的影响

Effects of quenching and tempering on microstructure and mechanical properties of low-carbon microalloyed steel

采用扫描电镜和拉伸试验机研究了C-Mn-Mo-Ni-Nb-Ti-V系低碳微合金钢950℃淬火和560~640℃回火调质处理对钢微观组织及力学性能的影响。结果表明,轧态钢板中含有大量细小均匀的粒状贝氏体(GB)组织,有良好的强韧性。调质后,试验钢获得板条贝氏体及铁素体的混合组织,随回火温度的升高,板条贝氏体回复作用逐渐加强,相邻板条合并,致使组织粗化。试验钢经950℃淬火+640℃回火后,其强度下降,韧性和塑性明显提高,伸长率为26.9%,-20℃夏比冲击吸收能量为392 J,断口剪切面积达到100%。

Effects of quenching at 950 ℃and tempering at 560-640 ℃on the microstructure and mechanical properties of C-Mn-Mo-Ni-Nb-Ti-V based low-carbon microalloyed steel were investigated by use of scanning electron microscopy ( SEM ) and tensile test machine .The results show that the microstructure of rolled state steel contains a large amount of fine and uniform granular bainite microstructure ( GB) which brings good strength and toughness .A multiphase microstructure with lath bainite and ferrite is achieved after quenching and tempering .With tempering temperature increasing , the recovery process of lath bainite is strengthened gradually , and adjacent lath is linked to combine , that leading to microstructure coarsening .After quenching at 950 ℃ and tempering at 640 ℃, the strength of the steel decreased, the plasticity and toughness obviously increased , and the elongation is 26.9%, Charpy impact energy at -20 ℃ is 392 J, the percentage of shear area reaches 100%.