轴承磷化花斑成因分析

针对西北轴承股份有限公司铁路轴承外套在生产过程中，突然出现磷化膜颜色深浅不均匀的云彩状花斑，进行成因分析．首先，经过对材料的分析，排除材料引起花斑的可能；然后对磷化工艺和热处理工艺进行模拟试验研究，最终发现主要问题是在热处理过程中，通过对磷化膜硬度、磷化膜结构、碳化物数量及分布作取样分析，弄清了352226—2RZ轴承磷化花斑的成因是工件采用天然气渗碳处理后，其表面有积碳，呈黑色花斑．经过对渗碳工艺进行改进，用甲醇、丙酮替代天然气进行渗碳处理，成功地解决了轴承表面生成磷化花斑，影响产品外观质量这一技术难题。

Analysis on the cause of formation of phosphate coating film speckles on bearing

The article mainly focuses on analyzing the cause of formation of phosphate coating film speckles on the outer ring of bearings in the manufacturing progress of railway bearing in Xibei Bearing Co. Ltd.,By analyzing the material of bearing and taking simulative research on the process of phosphate coating and heat treatment, it is found that the phosphate membrane forms in the process of heat treatment. Through sampling the phosphate membrane and analyzing its rigidity, structure and quantity and distribution of carbide, it is also found that the formation of phosphate spots of the 352226-2RZ type bearings results from the carbon deposition on the bearing surface after carburization treatment of natural gas, and that the effective solution of removing the phosphate spots on the outer surface of bearing is amending the operation sequence of carburising and replacing natural gas with carbinol and acetone in the process of carburising.