304不锈钢2B板表面线鳞缺陷改进实践

Improvement practice for the line scales on surface of 304 stainless steel 2B plate

针对304不锈钢2B板表面发生的线鳞缺陷,采用扫描电镜对缺陷处形貌和成分进行了分析,采用光学显微镜对同期生产的板坯、热轧卷进行夹杂物分析。结果表明,304线鳞缺陷是由CaO-SiO2-MgO夹杂物引起。在304不锈钢的工业生产中,通过控制炼钢过程工艺,有效改善了钢中夹杂物水平,并减少了304不锈钢2B板表面线鳞缺陷的发生率。改进后,板坯边部和中部试样中夹杂物以5~10μm为主,热轧板中C类硅酸盐夹杂和D类球状氧化物夹杂都为0.5级,线鳞缺陷的发生率跟改进前相比降低了1.35%。

To find out the reason for line-scales defects occurring on the surface of 304 stainless steel 2B plate,the microscopic morphology and the compositions of the defects were investigated using scanning electron microscope (SEM),and inclusions analysis was made among the continuous-casting slabs and hot-rolled plate produced in the same period.The results show that line-scales on the 2B plate surface were caused by the CaO-SiO2-MgO inclusions in the steel.The level of inclusion in steel was improved effectively by controlling steelmaking process in the indus-try.Furthermore,the line-scales defects in the 2B plate surface were reduced significantly.After the improvement, most of the inclusions size at the edge and the center of 304 slabs are between 5-10μm;the grade of CaO-SiO2-A1 2 O3 ciliate inclusion and the A1 2 O3-MgO-CaO globular oxide inclusion are all 0 .5 and the occurrence rate of the defects 1.35% lower than before.