Predicting the surface hardness of micro-milled nickel-base superalloy Inconel 718

The functional performance and the product life of micro-milled Inconel 718 parts highly depend on their mechanical properties such as excessive work hardening, which will reduce fatigue life, and the corrosion resistance of micro Inconel 718 parts. Also, work hardening can accelerate tool wear. Therefore, investigation of work hardening caused by micro-milling is important if we are to improve the functional performance and extend the life of microproducts such as Iconel718. However, few studies have developed methods of predicting the surface hardness of micro-milled parts. Thus, this paper uses 3D finite element analysis (FEA) based on ABAQUS to simulate the process of micro-milling Inconel 718. We simulated clamping, micro-milling, tool retracing, and constraint conversation stages with surface residual strains as output. Then, after identifying the relationship among Vickers hardness, the flow stress, and the flow strain of Inconel 718, we built the surface micro-hardness prediction model of micro-milled Inconel 718 and confirmed the accuracy and validity of the surface hardness prediction model by experiments. From the model, the influences of spindle speed, feed per tooth, and axial cutting depth on surface micro-hardness were determined.