30CrMnSiA钢结构件低温断裂失效分析

Low-temperature fracture failure analysis of 30CrMnSiA steel structural part

30CrMnSiA钢结构件在低温环境中在冲击载荷下发生了断裂。通过扫描电镜、金相显微镜、电感耦合等离子光谱仪(ICP)、硬度测试、拉伸试验、冲击试验等方法对断口形貌、显微组织和夹杂物、化学成分、硬度、拉伸性能和冲击性能等进行了测试分析。结果表明,调质处理过程中实际回火温度低于工艺要求的温度,导致30CrMnSiA钢组织全部转变成回火马氏体;回火马氏体在-40℃下冲击吸收能量较低,是导致-40℃低温环境中冲击作用下发生脆性断裂的主要原因;硫化物和硅酸盐等非金属夹杂物等级超过了设计要求,大量的夹杂物促进裂纹快速萌生和扩展。

Fracture of 30CrMnSiA steel structural part occurred under impact load in a low-temperature environment.The fracture morphology,microstructure and inclusions,chemical composition,hardness,tensile properties and impact properties were tested and analyzed by means of scanning electron microscope,metallurgical microscope,inductively coupled plasma spectrometer(ICP),hardness test,tensile test,and impact test.The results indicate that during quenching and tempering,the actual tempering temperature is lower than the required temperature,which results in the transformation of the metallographic structure into tempered martensite.The tempered martensite has low impact absorbed energy at-40℃,which is the main reason for brittle fracture under impact at-40℃.The grade of non-metallic inclusions such as sulfides and silicates exceeds the design requirements,and a large number of inclusions promote rapid crack initiation and propagation.