过负荷铜导线金相显微特征分析

Metallographic microcosmic characteristics analysis on overload copper wire

为考查铜导线金相组织随截面积、过负荷时间、倍数以及加热温度、加热时间、冷却方式的变化规律,本实验制备了不同线径的铜导线过负荷不同倍数和不同时间的试样,然后对过负荷铜导线在不同温度下加热不同时间并采取自然或喷水的方式进行冷却。通过观察过负荷铜导线试样的金相组织,分析过负荷铜导线金相组织随其形成条件的变化规律。结果显示,随过负荷时间的延长,铜导线金相组织由最初的纤维状组织变成柱状或等轴晶粒;过负荷倍数越大,形成的晶粒越大;当过负荷痕迹形成后,在低于其形成温度下加热,不影响其金相组织;导线截面积和冷却方式对铜导线金相组织影响不大。在实际火灾调查过程中利用过负荷铜导线的金相组织特征来证明火灾事实时,要综合考虑过负荷的形成过程。

In order to study the effect of sectional area, overload time, overload current, heated temperature, heated time and cooled pattern on the metallurgical structure of overload copper wire, samples of overload copper wire were made and the metallurgical structure were analyzed. The result shows three of the most important influenced factors are overload time, overload current and heated temperature. In order to reflect the fact of fire scene, comprehensive analysis based on the evidence is very important.