Softening mechanism of grinding surface metamorphic layer of GH4169DA

In order to study the softening mechanism of the grinding surface metamorphic layer of superalloy GH4169DA, the microstructure, Vickers hardness and γ″ phase density of the metamorphic layer are investigated by the metallographic microscope, micro Vickers and transmission electron microscopy (TEM). The results show that there is softening and local plastic deformation on the grinding surface and sub-surface of GH4169DA. In the range of the test parameters, the depth of the softened layer is approximately 30 μm to 100 μm, and the depth of the deformed layer is only about 4 μm. From the matrix to the grinding surface, the number of γ″ phase per square micron decreases gradually from about 2.27×10³ to zero, and the γ″ phase disappears completely within 2.2 μm depth of the grinding surface. The causes of the γ″ phase density vari-ation are basically the same as the variation of microhardness. The softening mechanism of the grinding surface of GH4169DA is that the main strengthening phase γ″ density decreases and its enhancement effect weakens under the action of the heat generated by the grinding process.