The residues of single-strand copper wire under different overcurrent were prepared with the integrated experimental system for fire trace material evidence. The fracture morphology of the wires were observed and analyzed by the scanning electron microscope. The results indicated that the fracture section and shear lip section of cup fracture became smaller and smaller, and the dimple of fibrous section got more and more small with the increase of overcurrent. The surface of shear lip section and neck shrink section transformed gradually from smooth to rough. Therefore, using scanning electron microscope to observe and analyze the fracture morphology of single-strand copper wire can identify whether the wire is overloaded and the degree of overload.%利用火灾痕迹物证综合实验台,制备单股铜导线在不同过载电流作用下的残留物,用扫描电子显微镜观察、分析导线的断口形貌.结果表明:随着过载电流的增大,导线杯状断口的断裂区和纤维区逐渐减小,纤维区韧窝逐渐减小,剪切唇区和颈缩区表面逐渐由光滑向粗糙转变.因此,利用扫描电子显微镜观察、分析单股铜导线断口的形貌特征,可以鉴别其是否过载以及过载的程度.
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