420 MPa级热基镀锌钢板表面爆皮的原因分析

Cause of Surface Blistering of 420 MPa Grade Hot-Based Galvanized Steel Plate

420 MPa级热基镀锌钢板表面产生爆皮缺陷。采用扫描电子显微镜、能谱仪和差热分析仪分析了镀锌板表面爆皮的特征和原因。结果表明:实质上爆皮是热轧板表面形成了疏松和分层的氧化铁皮,主要为FeO;该镀锌钢板的抗高温氧化性能不良,在990和1180℃左右的氧化质量增加速率急剧增大,导致钢板爆皮。通过优化粗轧机除鳞水、增加精轧机架间冷却水流量和调整卷取工艺等改进措施,表面发生爆皮的420 MPa级热基镀锌钢板大大减少。

The 420 MPa grade hot-based galvanized steel plate exhibited undesirable blistering on its surface.The characteristics and cause of surface blistering of the galvanized steel plate were analyzed by using scanning electron microscope(SEM),energy dispersive spectrometer(EDS)and differential thermal analyzer.The results showed that(a)in substance,the blistering was loose and layered iron oxide scale which was mainly composed of FeO;and(b)the galvanized steel plate showed poor resistance to high-temperature oxidation,and its oxidation weight growth rate at about 990 and 1180℃increased sharply,thus resulting in its surface blistering.The 420 MPa grade hot-based galvanized steel plates on which the blistering occurred were considerably decreased by the optimization of the descaling water of roughing mill,the increase in cooling water flow between the finishing mill stands and the adjustment of coiling process.