在对某低碳钢进行金相检验的过程中,发现其铁素体晶粒表面发灰。采用金相检验、腐蚀试验和划痕试验等方法研究了晶粒表面发灰的原因。结果表明:试样表面残留抛光划痕,使试样表面粗糙度变大,造成了漫反射现象;每个晶粒的位向不同,抛光划痕引起的内应力也不同,使得每个晶粒的腐蚀程度不同,从而引起了表面形貌的差异,最终导致铁素体晶粒表面发灰。

During the metallographic examination of a low carbon steel, it was found that the surface of ferrite grains turned gray. The reason for the surface graying of grains was studied by metallographic examination, corrosion test and scratch test. The results show that the reason for the graying of the grains was the residual polishing scratches on the surface of the sample, which increased the surface roughness of the sample and caused diffuse reflection phenomenon. The orientation of each grain was different, and the internal stress caused by polishing scratches was also different, resulting in different degrees of corrosion for each grain, which led to differences in surface morphology and ultimately led to graying of the ferrite grain surface.