摘要:
利用扫描电镜 (SEM)、透射电镜 (TEM) 和力学性能检验等试验方法, 研究了系列回火温度对TMCP处理的屈服强度550 MPa级抗震建筑用钢微观组织、第二相析出及力学性能的影响。结果表明, 随着回火温度的提高, 试验钢屈服强度和抗拉强度变化趋势一致, 屈强比呈明显的上升趋势。分析认为:回火前后力学性能的变化主要与回火后更多弥散的尺寸在25 nm以下的新的细小粒子析出以及M/A岛的分解和发生位错亚结构回复软化有关, 试验钢450℃回火后钢板具有最佳综合力学性能:抗拉强度为703 MPa, 屈服强度为588 MPa, 伸长率为17.5%, -20℃冲击吸收能量为240 J, 屈强比0.84满足建筑用钢要求。
Abstract:
Effects of tempering temperature on microstructure,precipitation and mechanical properties of Seismic building steel with yield strength of 550 MPa produced by TMCP,were researched by optical microscope,TEM and mechanical properties test. The results show that with the increase of tempering temperature,both yield strength and tensile strength of the test steel increase,and the ratio of Rp0.2/Rm increases obviously. The changes of mechanical properties before and after tempering are mainly related to the precipitation of fine particles below 25 nm size,the decomposition of M/A islands and the recovery of dislocation substructure after tempering. When the tempering temperature is 450 ℃,the best comprehensive mechanical properties of the tested steel are achieved with tensile strength at 703 MPa,yield strength at 588 MPa,elongation of 17.5% and impact energy at-20 ℃ reaching 240 J,as well as lower Rp0.2/Rm of 0.84.
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