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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30~100μm,而变形层的深度只有约4μm。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2.2μm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。
In order to further study the softening mechanism of the GH4169DA grinding surface, the microstructure, microhardness and γ “phase density of the superalloy GH4169DA were analyzed by optical microscope, micro Vickers hardness tester and transmission electron microscope (TEM) : GH4169DA softening and local plastic deformation of the surface and subsurface softening within the experimental parameters, the softening depth of about 30 ~ 100μm, while the depth of the deformation layer is only about 4μm from the substrate to the grinding surface, γ ”phase The density gradually decreased from about 2.27 × 10 3 / μm 2 to the complete disappearance of γ “phase within about 2.2 μm from the grinding surface.The change rule was consistent with the change law of microhardness and the maximum influence depth was basically the same.The analysis indicated that the GH4169DA grinding The fundamental reason for softening the surface softens is that the density of the main strengthening phase γ ”is reduced and the strengthening effect is weakened under the action of heat during the grinding process.