42CrMo4热轧板表面氧化铁皮掉粉缺陷分析及控制

Analysis and control of dropping defect of oxide scales on surface of 42CrMo4 hot rolled plate

针对精冲钢42CrMo4热轧板表面氧化铁皮掉粉缺陷,通过金相组织、物相检测、成分检测、生产关联性因素分析等手段,研究了其氧化铁皮成分、形貌、结构特征及其演变,讨论了热轧关键工艺参数控制与氧化铁皮形成的关系。研究结果表明,传统生产工艺中,掉粉缺陷热轧板的氧化铁皮厚度不均匀,厚度变化范围为10~19μm,其中FeO质量分数较高,达26.9%;当采用"高温快轧"配合"低温卷取"工艺可有效控制氧化铁皮的厚度及结构,抑制热轧板表面的氧化铁皮掉粉缺陷。当出炉温度为1190℃、终轧温度为860℃、穿带速度高于5.5 m/s、卷取温度为540℃、采用前段冷却、加大轧后冷却速度,可基本解决氧化铁皮掉粉缺陷。

The composition,morphology,structural characteristics and evolution of oxide scales on the surface of fine blanked 42 CrMo4 steel were studied using metallographic structure,phase detection,composition detection and production correlation factor analysis.The relationship between the control of the key technical parameters of hot rolling and the formation of oxide scales was discussed.The results show that for the traditional production process,the thickness of oxide scales with dropping defect is uneven,ranging from 10 to 19μm,and the mass fraction of FeO in oxide scales is high,up to 26.9%.With the"high-temperature rapid rolling"and"low-temperature coiling process",the thickness and structure of oxide scales can be controlled effectively and the dropping defect on the surface of the hot-rolled plate can be suppressed.The dropping defect of oxide scales can be solved by front cooling and big cooling rate after rolling under the condition of the tapping temperature of 1190℃,the finished rolling temperature of 860℃,the threading speed higher than 5.5 m/s,and the coiling temperature lower than 540℃.