Another important factor has been working hard cutting surface quality is the formation of a white layer. White layer is accompanied by a form of hard-state organization formed by the cutting process, it has a unique wear characteristics: one high hardness, good corrosion resistance; on the other hand showed a higher brittleness, can lead to early spalling failure. Thin white layer size, it is difficult to accurately analyze its organizational characteristics, its formation mechanism are still controversial. One view is that the white layer is the result of the phase transition is the fine grain material is fine martensite by rapid heating and sudden cooling in the cutting process and the formation of the composition. Another view is that only part of the formation of a white layer deformation mechanism, but obtained by plastic deformation unconventional type martensite. Currently regarded as the white layer martensite view has been unanimously approved, the main controversy lies in the fine structure of the white layer. ykchou and cjevans think hard cutting process of the formation of a white layer and cutting heat-related, increasing the amount of flank wear white layer will lead to greater depth, in the vb reach 0.31mm white layer depth of up loμm. b. j. griffiths think cutting process causes the phenomenon of self-layer high-speed sliding wear, white layer of tissue morphology is ultra-fine grain structure of austenite and martensite mixed structure, and is closely related to tool wear. Therefore, further study of eight deep white layer formation mechanism and its impact on the life of parts.