不锈钢典型夹杂物在轧制过程的衍变分析

Analysis for evolution of typical inclusions in stainless steel during rolling

不锈钢对冷板表面质量要求高,轧制过程中夹杂物是产生表面缺陷的主要原因之一。为了明确夹杂物对轧制过程表面缺陷的影响规律,通过中试模拟试验研究了热轧、退火和冷轧过程硬质镁铝尖晶石和低熔点硅酸盐2种典型夹杂物的变形特点,并采用数值模拟对冷轧过程夹杂物的变形机理进行了分析。结果表明,热轧过程高熔点的镁铝尖晶石不变形,低熔点的硅酸盐夹杂物在1200~1250℃热轧温度下为半熔融状态,具有良好的变形能力。硅酸盐夹杂物长宽比高、抗拉强度低,冷轧过程更容易断裂延伸,随着轧制的进行,断裂后夹杂物之间的距离逐渐增加,尺寸减小。相反,镁铝尖晶石不容易断裂、延伸,而且存在断裂延伸的临界尺寸,该临界尺寸随冷轧变形量的增加而减小。由于镁铝尖晶石容易造成不锈钢轧制缺陷,因此生产过程中应尽量避免其生成或控制其粒径。

Stainless steel requires high surface quality of cold plate, and inclusions are one of the main reasons for surface defects during rolling. In order to clarify the effect of inclusions on surface defects in rolling process, the deformation characteristics of two typical inclusions, hard magnesia alumina spinel and low melting point silicate, during hot rolling, annealing and cold rolling were studied through pilot scale simulation experiments, and the deformation mechanism of inclusions during cold rolling was analyzed by numerical simulation. The results show that the high melting point magnesia alumina spinel does not deform during hot rolling, and the low melting point silicate inclusions are semi molten at the hot rolling temperature of 1200-1250 ℃, which has good deformation ability. Silicate inclusions have high aspect ratio and low tensile strength, so it is easier to fracture and extend during cold rolling. With the progress of rolling, the distance of inclusions after fracture gradually increases and the size decreases. On the contrary, magnesia alumina spinel is not easy to fracture and extend, and there is a critical size of fracture and extension, which decreases with the increase of cold rolling deformation. As magnesia aluminum spinel is easy to cause stainless steel rolling defects, its formation should be avoided or its particle size should be controlled in the production process.