非金属夹杂物影响下SCM-420钢的失效行为

摘要

In order to study the effect of non-metallic inclusions on the microstructures of steel,the morphology of inclusions,microstructure of matrix and failure fracture surface of SCM-420 structural steel were observed and analyze with optical microscope（OM）,scanning electron microscopy（SEM）,micro-hardness tester and energy dispersive spectrometer（EDS） equipped on SEM.The results indicate that the inclusions are mainly dot-like oxide and silicate mixture,lumpish oxide and strip silicate.The decarburized layer is observed around the inclusions,and its microstructure is composed of single-phase ferrite.The eutectic-like microstructure forms due to the reaction between inclusions and matrix.The non-metallic inclusions and decarburized layer can be regarded as the channel of microcracks,which results in the brittle fracture of SCM-420 structural steel.%为了研究非金属夹杂物对钢内部显微组织形态的影响,利用金相显微镜、扫描电子显微镜、显微硬度计和扫描电镜EDS能谱仪对SCM-420机械结构用钢内部的夹杂物形貌、基体微观组织、失效断口进行了观察分析.研究结果表明：夹杂物主要为点状的氧化物-硅酸盐混合型、块状的氧化物型和条状的硅酸盐型;夹杂物的周围存在脱碳层,其显微组织为单相的铁素体;夹杂物与基体生成了类共晶组织;微裂纹以夹杂物和脱碳层为通道,导致SCM-420机械结构用钢的脆性断裂.