【摘要】 运用电子显微技术研究了ＱＴ型微合金高强钢模拟焊接热影响区粒状贝氏体的微观结构．结果显示，在金相截面上呈长条形的Ｍ－Ａ组元的空间形态为薄板状；而在金相截面上呈不规则多边形的Ｍ－Ａ组元的空间形态为近似于等轴的块状．Ｍ－Ａ组元与铁素体之间的界面可进一步划分为马氏体／铁素体界和残余奥氏体／铁素体界在具有块状Ｍ－Ａ组元的粒状贝氏体团中，贝氏体与铁素体之间有高角晶界相隔，并分析和讨论了这些现象与解理断裂和韧性的关系。更多还原

【Abstract】 Electron microscopy was employed to investigate the microstructures of granular bainite in simulated heat affected zone of a QT type microalloyed high strength steel. The results show that the martensite and austenite (M-A) particles having elongated shape on cross sections are plate-like in three dimensions, while those having irregular polygonal shape on cross sections are close to equiaxial block in three dimensions. The interface between an M-A particle and its surrounding ferrite can be further classified into the interface between martensite and ferrite as well as that between austenite and ferrite. High-angle boundaries were found out between the grains of the ferrite in a bainitic packet with block M-A particles. The relationship between the microstructures, cleavage fracture and toughness was also discussed.更多还原