Surface Integrity of Inconel 738LC Parts Manufactured by Selective Laser Melting Followed by High-speed Milling

Abstract

This study is concerned with the surface integrity of Inconel 738LC parts manufactured by selective laser melting (SLM) followed by high-speed milling (HSM). In the investigation process of surface integrity, the study employs ultra-depth three-dimensional microscopy, laser scanning confocal microscopy, scanning electron microscopy, electron backscatter diffractometry, and energy dispersive spectroscopy to characterize the evolution of material microstructure, work hardening, residual stress coupling, and anisotropic effect of the building direction on surface integrity of the samples. The results show that SLM/HSM hybrid manufacturing can be an effective method to obtain better surface quality with a thinner machining metamorphic layer. High-speed machining is adopted to reduce cutting force and suppress machining heat, which is an effective way to produce better surface mechanical properties during the SLM/HSM hybrid manufacturing process. In general, high-speed milling of the SLM-built Inconel 738LC samples offers better surface integrity, compared to simplex additive manufacturing or casting.

The Relevance of Process Parameter Optimization and Geometric Figure for Direct Laser Deposition of Inconel 738 Alloy and Its Theoretical Modeling

“…Inconel 738 exhibits an excellent high-temperature strength, toughness, hardness, and resistance to heat corrosion, making it a popular choice for various applications, such as ships, industrial gas turbines, nuclear reactors, and petrochemicals. It is also used in highend components, such as aeroengines and supersonic airplanes [1,2]. However, Inconel 738 faces problems with weldability and susceptibility to hot cracking, which significantly impact its machinability and the performance of its components.…”

Machinability of Selective Laser Melted 17-4 PH Stainless Steel in Turning Process

“…Different post-processes have been used to improve roughness such us sandblasting [5], laser shotpeening [6] or electrochemical polishing [7], but when the dimensions and geometry of the parts are also critical, post processing by machining is necessary. In this context, hybrid processes emerge as a solution to obtain precision metal parts, where the addition of material is combined with the removal of material in the areas of the part where it is necessary to achieve high dimensional and surface quality [8,9]. Knowledge of the machinability of the materials manufactured by SLM plays a fundamental role in the development of these hybrid processes.…”