卷取温度和随后的冷却方式对65Mn钢板表面质量的影响

Effect of Coiling Temperatures and Subsequent Cooling Way on Surface Quality of 65Mn Steel Sheet

热轧65Mn钢板表面常存在粉化的氧化皮,导致酸洗后钢板表面有色差。为解决这一问题,研究了热轧后在不同温度卷取随后以不同方式冷却的65Mn钢板发生表面氧化的原因。结果表明:热轧后在700~730℃卷取随后坑冷的65Mn钢板表面氧化皮粉化最严重,而热轧后在600~620℃卷取随后空冷的65Mn钢板表面氧化铁皮粉化最轻微,这是因为较高的卷取温度使钢板表面发生了较严重的脱碳和晶间氧化,晶界耐蚀性降低,酸洗过程中产生色差;热轧后在600~620℃卷取随后空冷的65Mn钢板表面晶间氧化深度从20μm下降至小于5μm,脱碳程度明显减轻,晶界耐蚀性提高,酸洗后色差减少。

Pulverized oxide scale frequently exists on the surface of hotrolled 65Mn steel sheet,which results in formation of a chromatic difference on its surface after pickling.To solve this problem,the reason why the surface of 65Mn steel sheet coiled at different temperatures then cooled in different ways after hotrolling was oxidized was investigated.The results showed that(a)the pulverization of oxide scale was the most severe on the surface of 65Mn steel sheet coiled at temperatures of 700 to 730℃and then cooled in pit after hotrolling,and was the most slight on the surface of 65Mn steel sheet coiled at temperatures of 600 to 620℃and then cooled in air after hotrolling,which arose from that the higher coiling temperature rendered decarbonization and intergranular oxidation of the sheet surface more severe,thus resulting in a decrease in corrosion resistance of the grain boundary and the occurrence of chromatic difference during pickling;and(b)the depth of intergranular oxidation of the surface of 65Mn steel sheet coiled at temperatures of 600 to 620℃and then cooled in air after hotrolling decreased from 20μm to less than 5μm,and the decarburization degree was obviously reduced,thus being improved in the corrosion resistance of the grain boundary,and being decreased in the chromatic difference after pickling.