热镀锌双相钢表面粗糙问题分析与控制

 目前强度级别较高的双相钢产品已经可以普遍采用热镀锌工艺生产，热镀锌双相钢在生产过程中，表面出现明显的粗糙缺陷，形成边部与中部的色差，严重影响热镀锌双相钢产品表面质量。粗糙缺陷伴随粗糙度异常升高、锌层不均、抑制层形成不良、基板表面微裂纹等现象。分析认为，基板表面微裂纹是造成热镀锌双相钢表面粗糙的主要原因。热轧态组织和冷轧压下率是决定冷硬板浅表层微裂纹形成的关键因素。通过优化卷取温度及热轧卷厚度，改善热轧态组织及降低冷轧压下率，可有效控制冷轧板表面浅表层微裂纹的形成，从而良好解决热镀锌双相钢表面粗糙问题。

Analysis and control of coarse surface of galvanized dual phase steel

Hot dip galvanized steel with high strength such as DP(dual phase)steel has been widely produced. During the galvanizing process of DP steel,coarse surface defect isfound on the surface of the zinc layer which causes severe colour difference between the edge and the middle of the strip. Coarse surface defect has very bad effect on the surface quality of the galvanized strip. The abnormal increasement of the roughness,the uneven zinc layer,the low-quality inhi-bition layer and the microcrack on the substrate surface are always in company with the coarse surface defect. The micro-crack on the substrate surface is considered to be the main reason of the coarse surface defect of the DP steel. The micro-structure of the hot rolled strip and the reduction ratio of the cold rolling process are the key factors to determine the mi-crocrack on the substrate surface. The formation of the microcrack on the substrate surface can be eliminated by optimiz-ing the microstructure of the hot rolled strip and reducing the reduction ratio of the cold rolling process and the coarse surface problem can be solved effectively.