摘要
采取硬度检测、拉伸试验、金相检验和化学成分分析等方法,对不同铸造工艺HT250铸件的表面孔洞缺陷进行调查与分析。结果表明:HT250铸件硬度明显低于国家标准要求,部分铸件的抗拉强度不满足国家标准要求,金相组织中铁素体含量较高(珠光体含量低于85%),石墨粗大、不均匀,化学成分不满足企业标准要求。孔洞缺陷是其加工表面在高速切削力作用下,石墨块脱落并同时牵扯着周边的铁素体一起塌陷下来,从而形成大小不等的凹坑。
The surface hole defects of HT250 casting were investigated and analyzed by hardness testing,tensile testing, metallographic inspection and chemical composition analysis.The results show that the hardness is obviously and the tensile strength is partially lower than the standard requirements,the ferrite content is relatively high and the graphite is non-uniform, the chemical composition doesn＇t meet the requirements.The hole defects are cutting pits which formed due to graphite shedding with surrounding ferrite collapsing under the high speed cutting force.
出处
《失效分析与预防》
2011年第4期229-231,260,共4页
Failure Analysis and Prevention
