20Cr13马氏体不锈钢表面麻坑缺陷成因分析

Analysis of Pockmarks Formed on the Surface of 20Cr13 Martensitic Stainless Steel

以表面出现质量问题的20Cr13马氏体不锈钢餐刀为研究对象,描述了20Cr13马氏体不锈钢热轧板经抛光后表面麻坑缺陷的宏观形貌特征,并采用扫描电镜对表面麻坑缺陷的形态、组成进行微观分析。结果表明,麻坑缺陷的微观形貌为大小不同的孔洞、凹坑和压痕;孔洞边缘处存在大量氧元素的富聚,表明在孔洞边缘存在大量的氧化皮;凹坑处会伴有硅酸盐类夹杂物存在,加速凹坑处的点蚀和缝隙腐蚀,促使孔洞缺陷形成;压痕是由存在大量不同方位且相互垂直的划痕组成,划痕的方向与对餐刀氧化皮打磨方向一致。由此可知20Cr13不锈钢热轧板的氧化皮厚度以及夹杂物的存在对麻坑缺陷的出现有着重要影响,因此减少热轧氧化皮的厚度和提高钢水纯净度可有效地避免麻坑缺陷的产生。

The surface defects of martensitic stainless-steel table knives were analyzed.The macro-morphology and characteristic of pockmark defects on the surface of martensitic stainless steel were described,a nd the micro-morphology and component were analyzed by scanning electronic microscopy and energy dispersive spectrometer.The results show that the micromorphology of pockmark defect are various hole,pit and rough.Enough oxygen elements enrich at edge of hole defects,which means there are a lot of oxide scale at edge of hole defects.Silicate inclusions exist in in the pit defects,which accelerates pitting and crevice corrosion and promoted the formation of hole defects.Rough defects are composed of surface scratches,whose scratches are nearly vertical to each other and their direction is consistent with the rubbing direction.So,it can be concluded that avoiding thicker oxide scale and inclusions can prevent pockmark defects on the surface of 20Cr13 martensitic stainless steel.