火灾现场中铜包钢导线熔痕金相鉴别技术研究

Research on Metallographic Identification Technology of Melted Marks of Copper-clad Steel Wire in Fire Scene

模拟火灾现场中铜包钢导线熔痕产生的条件,制备一、二次短路熔痕和火灾热作用导线痕迹。使用金相分析法,寻找最佳金相浸蚀剂,研究一、二次短路熔痕的金相组织特点。结果表明,4%硝酸酒精是最佳浸蚀剂,一次短路熔痕的组织以较细的马氏体为主,及少量暗色托氏体,存在气孔;二次短路熔痕中以马氏体为主,晶界处有铁素体析出,不存在托氏体,几乎没有气孔存在。

The generation condition of wire melted marks in fire was simulated. Primary and secondary circuited melted marks and the trace caused by fire heat effect of copper-clad steel wire were made. Using metallographic analysis method, chosing the best reagent, the metallographic structure features of primary and secondary circuited melted marks were studied. The results indicate that 4% nitric acid alcohol is the best reagent, and primary circuited melted mark structure is mainly composed of fine martensite and small amount of dark troostite and there are some internal gas boles. Secondary circuited melted mark is also mainly composed of martensite, and some ferrite precipitates in grain boundary, there is no troositite, and few gas holes are found.