冷轧锯片钢喷粉起泡问题分析及解决措施

Analysis and solution of bubble problem during powder injection of cold rolled saw steel

为了研究冷轧锯片钢65Mn在客户使用过程中出现喷粉后起泡现象的原因,通过扫描电镜对起泡位置及基板表面进行观察,起泡位置表层存在针眼状孔洞,基板表面存在密集分布的微小裂纹。通过光学显微镜及荧光分析对基板组织及表层成分进行分析,基板表层存在5~10μm的脱碳层,其深度与裂纹深度相当。分析表明,在客户酸洗锯片钢过程中酸液在微裂纹内部残留,在喷粉过程中与基板反应生成气体,是造成65Mn喷粉起泡的主要原因。控制热轧加热温度及保温时间改善脱碳现象,配合冷轧过程加入一次罩式退火可改善带钢表面微裂纹,能有效控制喷粉起泡问题的发生。

To research the bubble problem occurred during the powder injection of cold rolled saw steel 65Mn, the bubble position and substrate surface were observed by SEM. Small holes can be found on the surface of bubble po- sition and micro cracks can be found on the surface of the substrate. Optical microscope and X-ray fluorescence anal- ysis were used to analyze the microstructure of the substrate and the element content of the surface layer. Decarburi- zation layer with the depth of 5-10 μm can be found on the surface of substrate, whose depth was comparable to the crack depth. The analysis showed that after the pickling process, the residual acid inside the microcrack reacted with the substrate to generate gas during the powder injection process, which was the main cause of the defect. By con- trolling the heating temperature and holding time during the hot rolling process, the decarburization phenomenon can be alleviate. Batch annealing process was applied after the four passes cold rolling, which can alleviate the micro cracks and effectively solve the bubble problem.