离心轧辊花斑问题的形成原因分析

Analysis of the Causes for the Formation of Centrifugal Roll Piebald Problem

针对轧辊使用中出现的花斑缺陷问题,利用金相显微镜、电子探针等工具对花斑区和正常区进行微观组织观察与区域元素分布测量,并对微观组织进行量化分析,探讨了轧辊花斑的形成原因。结果表明,花斑问题的产生和轧辊表面氧化程度关联,而氧化程度和局部渗碳体尺寸密切相关。花斑区组织和正常区相比更为细小,花斑区尺寸大于100μm的渗碳体占比不足30%,正常区尺寸大于100μm的渗碳体占比接近80%。组织差异造成正常区氧化程度较高,颜色偏暗;而花斑区氧化较为分散,未形成大块氧化区域;两个区域的氧化程度差异造成了花斑现象。花斑现象形成原因的分析,有利于下一步离心铸造轧辊的制备工艺设计与优化,获取均匀组织以改善花斑问题。

In view of the piebald defects in the use of rolls,optical microscope and electron probe micro-analysis were used to perform the microstructure observation and regional element distribution in the piebald and normal areas,and the quantitative analysis of microstructure was carried out,then the causes of the piebald formation of rolls were discussed.The results show that the generation of speckles is related to the oxidation degree of roll surface,and the oxidation degree is closely related to local cementites size.Compared with the normal area,the microstructure in the piebald area is finer,and the percentage of cementites size more than 100μm in the piebald area is less than 30%,while that in the normal area is close to 80%.The microstructure difference causes that the normal area is easier to be observed by naked eyes after oxidation,and the color is darker.However,the oxidation in the spotted area is scattered,and no large oxidized area is formed.Owing to the difference of oxidation degree in these two areas,the piebald phenomena are observed.The analysis of the causes of piebald phenomenon is beneficial to the design and optimization of the preparation process of centrifugal roll in the next step,so as to obtain uniform structure and improve the speckle problem.