热得快通电干烧时内有电热丝的部位套管温度很高, 材料会发生二次再结晶、晶粒异常长大现象, 而无电热丝的部位温度不太高, 材料晶粒形态变化不明显。根据上述特征, 提出了通过对比套管材料不同部位的晶粒尺寸和组织形态的变化来鉴定热得快是否存在通电干烧的方法。模拟试验和理论分析结果均表明: 该方法可以分析热得快套管材料不同部位的受热状态, 进而能够确定热得快是否存在通电干烧现象以及火灾是否由热得快通电干烧引起的。

When immersion heaters were electrified overheating, secondary recrystallization could be observed on cannula at the partition with heating cord in it, but could not be observed at the partition without heating cord in it. A new material evidence identification method, by comparing the grain size and microstructure state of cannula at different partition, was proposed to certify whether the immersion heaters were electrified overheating or not. The results of simulation experiments and theory analysis show that it’s feasible to identify whether the fire hazard was caused by electrified overheating of immersion heater or not.