屈服强度550 MPa级抗震建筑用钢回火性能研究

Research on Tempering Performance of Anti-seismic Building Steel with 550 MPa Yield Strength

利用扫描电镜(SEM)、透射电镜(TEM)和力学性能检验等方法,研究了系列回火温度对TMCP工艺生产屈服强度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、尺寸<25 nm的细小粒子析出及M/A岛分解、位错亚结构回复软化有关。试验钢板经450℃回火后具有最佳综合力学性能,抗拉强度703 MPa,屈服强度588 MPa,伸长率17.5%,-20℃冲击吸收能240 J,屈强比0.84,满足抗震建筑用钢要求。

By means of various methods such as SEM,TEM and mechanical properties testing,the paper studies the effect of series tempering temperature on microstructure, second phase precipitation and mechanical properties of 550 MPa yield strength anti - seismic building steel produced by TMCP process. The results show that with increase of tempering temperature, the yield strength and tensile strength for the test steel plate are in the same trend, and the ratio of yield and tensile strength increases obviously. The analysis verifies that the variation of mechanical properties before and after tempering mainly relates to the more dispersed fine granular precipitate below 25 nm in size, M/A islands de-composition ,recovery and softening of dislocation substructure after tempering. The steel plate as tempered at 450 °C is of optimized comprehensive mechanical properties,l, e. ,tensile strength of 703 MPa,yield strength of 588 MPa,elonga-tion ratio of 17. 5% , impact absorbed energy at -20 T of 240 J and ratio of yield and tensile strength of 0. 8 4,which satisfies the requirements of anti - seismic building steel.