积屑瘤的稳定性与显微裂纹

The Stability of Built-up Edge(BUE)and Its Microcracks

利用光学和电子显微镜对20钢在两种切削参数下,形成的积屑瘤的金相显微组织与结构进行了观察.结果表明:积屑瘤具有纤维状结构,积屑瘤中各部位的形变率不同;某些部位有碳的偏聚现象.其组织类似于珠光体结构;对积屑瘤的受力状态及其各部位的形变率的差异进行了讨论。大量裂纹的存在.削弱了积屑瘤的强度.是引起积屑瘤不稳定性的因素之一.

By means of optical and electron microscopy,an examination is carried out on the metallurgical microstructure of a built up edge(BUE)which is formed in the 0.2% C steel with two kinds of cutting parameters.The BUE so formed is of a fibrous structure,with quite different deformation rate in its different parts.Some parts of the BUE have a biassing aggregation of carbon and show a structure similar to that of pearlite.The discussion centres on the relation between the stress distribution of different parts of BUE and its defor- mation difference.Lots of microcracks are bound to weaken the strength of the BUE and so become one of the factors of its unstability.