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用扫描电镜和金相显微镜对Q460D高强度结构钢不同几何形状试件断口处的微观形貌和组织变化进行了分析。结果表明:在高应力三轴度纯拉状态下,Q460D结构钢断裂呈空穴聚合型穿晶断裂,微观组织发生抛物线状的聚合变形;在应力三轴度为零的纯剪状态下,断裂呈脆性穿晶解理断裂,微观组织变形成长条状且铁素体变形较大;在低应力三轴度拉剪状态下,断裂呈抛物线形韧窝穿晶断裂,微观组织中铁素体变得粗大,珠光体变得细小;而在高应力三轴度平面应变状态下的断裂呈韧窝型沿晶断裂。
The microstructures and microstructures of Q460D high-strength structural steel specimens with different geometries were analyzed by SEM and optical microscope. The results show that the fracture of Q460D structural steel is a hole-type transmembrane transgranular fracture and the microstructure is parabolic deformed under purely tensioned triaxial condition of high stress. In purely sheared state with stress triaxiality of zero, fracture Brittle transgranular cleavage fracture microstructure deformed strip growth and ferrite deformation larger; in low stress triaxial shear state, the fracture was parabolic ductile transgranular fracture, the microstructure of ferrite becomes Coarse, pearlite becomes small; and in the high-stress triaxial plane strain state fracture dimple-like intergranular fracture.