汽车大梁用高等级钢板表面质量控制

Control of Surface Quality of Premium Grade Steel Plate for Automobile Girder

汽车大梁用高等级钢板酸洗后表面局部发黑。采用扫描电子显微镜、辉光放电光谱仪、电子探针显微分析仪和三维形貌仪等研究了酸洗后钢板表面发黑的原因。结果表明:酸洗板表面发黑处呈沟壑状,其粗糙度大于正常处,且有较多含Ti和Mn的颗粒物;Ti、Mn等合金元素不均匀地富集于热轧钢板表面,且由于精轧工序用水量过大,影响钢板表面氧化铁皮的结构,酸洗后钢板表面较粗糙,从而导致钢板表面局部发黑。通过将原材料钛的质量分数从0.12%降至0.07%,并将精轧入口温度提高20℃,酸洗后汽车大梁用高等级钢板表面的发黑现象显著减少。

Surface of premium grade steel plate for automobile girder darkened partially after being pickled.The reason why the steel plate surface darkened was investigated via scanning electron microscope,glow-discharge spectrometer,electron probe microanalyzer,and three-dimensional morphometry.The results indicated that(a)the darkened area on the pickled plate was in the form of gully,and exhibited greater roughness than did the normal area and more titanium-containing and manganese-containing particles;and(b)titanium,manganese and other alloy elements concentrated non-uniformly on surface of the hot-rolled steel plate,and due to excessive water consumption in the finishing rolling process step,the structure of oxide scale on the hot-rolled plate surface was affected and the steel plate surface became rougher after pickling,thus resulting in partially dark surface of the steel plate.The surface darkening phenomena of premium grade steel plate for automobile girder after pickling were greatly reduced by the decrease from 0.12%to 0.07%by mass in titanium content of the raw material and the increase of 20℃in the finish rolling entry temperature.