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New Approach to Distinguish Copper Molten Marks Based on Quantitative Microstructure Analysis Using Electron Backscatter Diffraction
Fire Technology ( IF 3.4 ) Pub Date : 2021-01-11 , DOI: 10.1007/s10694-020-01076-9
Jinyoung Park , Joo-Hee Kang , Eui Pyeong Lee , Young Ho Ko , Sun Bae Bang

Molten marks identified at a fire site can aid in determining the cause of a fire. Quantitative analysis of such molten marks has not yet been reported, despite several identification methods for molten marks being proposed based on optical micrographs. Herein, we propose a new methodology to establish the quantitative microstructure parameters of the molten marks using electron backscatter diffraction (EBSD). The globules were generated by heating the copper conductor to 1100°C in a non-energized state. Then, the arc beads were prepared by shorting the copper wire at 25°C and 900°C in an energized state. The globules did not show evident demarcation lines and indicated that the microstructure consisted of globular or dendritic grains; this demonstrated that their characteristics were distinctly different from those of arc beads. However, the primary arc beads (PABs) shorted at 25°C exhibited a strong (001) texture perpendicular to the demarcation line and comprised large fractions of columnar grains with a small grain aspect ratio (GAR). The microstructure of secondary arc beads (SABs) shorted at 900°C presented a mixture of elongated and equiaxed grains with a large GAR and no specific development of texture. The GAR and (001) fraction perpendicular to the demarcation line could be discriminant parameters of PABs and SABs. Consequently, EBSD methods can be newly applied for the classification of globules, PABs, and SABs based on the quantitative microstructure information and orientation distribution.



中文翻译:

基于电子背散射衍射定量显微分析的铜熔痕识别新方法

在火灾现场发现的熔融标记可以帮助确定起火的原因。尽管已经提出了几种基于光学显微照片的熔融痕迹识别方法,但尚未对这种熔融痕迹进行定量分析。在这里,我们提出了一种新的方法,利用电子背散射衍射(EBSD)建立熔融痕迹的定量微观结构参数。通过在非通电状态下将铜导体加热到1100°C来生成小球。然后,通过在通电状态下将铜线在25℃和900℃下短路来制备电弧珠。小球没有显示明显的分界线,表明其微观结构由球状或树枝状晶粒组成。这表明它们的特性与电弧珠的特性明显不同。然而,在25°C时短路的初级电弧珠(PAB)在垂直于分界线的地方表现出很强的(001)织构,并且包含大比例的柱状晶粒,且晶粒长径比(GAR)小。在900°C下短路的次级电弧珠(SAB)的微观结构呈现出伸长和等轴晶粒的混合物,并带有较大的GAR,并且没有特定的组织结构。垂直于分界线的GAR和(001)分数可以作为PAB和SAB的判别参数。因此,EBSD方法可以基于定量的微结构信息和取向分布而被新用于球体,PAB和SAB的分类。

更新日期:2021-01-11
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