By simulating the fire scene, the use of fire traces of evidence prepared by the comprehensive test-bed copper wire shorted secondary bead, use homemade indoor simulated fire box temperature thermal environment, under different conditions of temperature and time on copper wires shorted secondary bead in The reason is heated, cooled to take a different approach, and through repeated experiment to observe the metallurgical microstructure, identify the impact of copper wire shorted secondary factors and variation of microstructure bead stability, and thus affect the stability of in-depth analysis. Experimental results show that the temperature of the fire scene, fire duration and cooling methods have some effect on the stability of secondary copper wires shorted bead metallurgical microstructure; temperature has a greater impact on the stability of the grain volume; heating time less impact on the stability of the grain volume; when cooled immediately, cooling impact on the volume of grain. The grain morphology under various conditions has high stability. In the identification process can be analyzed according to characteristics of microstructure shorted bead fire identified extracted cause of the fire, which identify the cause of the fire was an electrical fire departments of public security to provide a favorable scientific evidence.%通过模拟火灾现场，利用火灾痕迹物证综合实验台制备铜导线二次短路熔珠，利用自制控温箱模拟室内火灾热环境，对铜导线二次短路熔珠在不同温度和时间的条件下进行加热处理，采取不同的方式冷却，并通过重复性实验，观察其金相显微组织，找出影响铜导线二次短路熔珠金相显微组织稳定性的因素和变化规律，从而对影响稳定性的原因进行深入分析。实验结果表明，火灾现场的温度、火灾持续时间和冷却方式对铜导线二次短路熔珠金相显微组织的稳定性有一定的影响；温度对晶粒体积的稳定性有较大的影响；加热时间对晶粒体积的稳定性影响较小；立即冷却时，冷却方式对晶粒的体积有影响。而晶粒形态在各种条件下均具有较高的稳定性。在鉴定过程中，可根据火灾中提取的短路熔珠的金相显微组织特征分析鉴定火灾起因，从而为公安消防部门查明电气火灾原因提供有利的科学证据。
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