The metallographic structure of melted mark was observed and metallographic structure with secondary short circuited melted mark and primary short circuited melted mark was found.

• 利用金相显微镜对火烧熔珠的金相组织进行观察,发现铜导线火烧熔痕在不同温度下经消防射水冷却后,会出现类似一次短路和二次短路熔痕的金相组织。