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通过对国内某厂生产的700 MPa级别汽车大梁钢热轧板进行力学性能检测,发现拉伸断口产生分层现象,利用金相显微镜、扫描电镜、透射电镜与能谱分析等手段研究其断后分层现象并分析其产生的原因。试验钢的平均屈服强度与抗拉强度分别为766.9、839.0 MPa,平均断后伸长率为19.2%,皆达到性能指标的要求。研究结果表明,铸坯与轧材中的夹杂物与析出物分布情况较好,不是产生分层现象的主要原因,热轧板厚度方向中部的贝氏体与马奥岛成带状偏聚,造成厚度方向上明显的塑性差异,直接导致了分层现象产生。试验钢产生拉伸分层的原因被解析出,为实际生产提供了改进方向。
The mechanical properties of hot rolled steel plate of 700 MPa grade automobile girder produced in a certain factory in China were tested and the stratification of tensile fracture was found. The microstructure of the hot rolled steel plate was observed by optical microscopy, scanning electron microscopy, transmission electron microscopy and energy spectrum analysis Layer phenomenon and analyze its causes. The average yield strength and tensile strength of the test steel were 766.9,839.0 MPa and the average elongation at break was 19.2%, all of which met the performance requirements. The results show that the distribution of inclusions and precipitates in slab and rolled material is good, which is not the main reason for stratification. The bainite in the middle of the hot rolled plate is segregated with the island of Maior, Resulting in a significant difference in the thickness of the plastic, a direct result of stratification. The reasons for the tensile stratification of the test steel were resolved, providing an improvement direction for actual production.