GH4169DA磨削表面变质层软化机理

为了深入研究高温合金GH4169DA磨削表面变质层软化机理，分别采用光学显微镜、显微维氏硬度计和透射电子显微镜（TEM）分析了其微观组织、显微硬度和γ"相密度。试验结果表明：GH4169DA磨削表面及亚表面发生了明显软化和局部塑性变形。在试验参数范围内，软化深度约为30~100 μm，而变形层的深度只有约4 μm。从基体到磨削表面，γ"相密度由约2.27×10³个/μm²逐渐降低，至距磨削表面约2.2 μm以内γ"相完全消失。该变化规律与显微硬度变化规律一致，最大影响深度也基本相同。分析指出，GH4169DA磨削表面软化的根本原因是在磨削过程中热的作用下，主要强化相γ"密度降低，强化效果减弱。

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.