[Abstract] Belt grinding (BG), widely used in Inconel 718 machining, can result in desired surface strengthening. However, the grinding-induced strengthening effect diminishes in subsequent belt polishing (BP), thus deserving special attention. This paper proposes isotropic etching polishing (IEP) as an alternative finishing process to effectively retain the robotic BG strengthened layer and concurrently improve the surface quality of BG Inconel 718. The strengthening effect and quality of surface layers processed by BG, BG + BP and BG + IEP are systematically compared and evaluated. The results indicate that BG can introduce an ~150-μm-thickness gradient strengthened layer, featured by high microhardness, significant domain refinement, large microstrain increment, high residual compressive stress, and a strong 〈100〉 texture. The optimized IEP retains approximately 86.1% (maximum) of the strengthening effect and 75.1% of the BG strengthened layer. The microhardness of the BG + IEP surface reaches 523 HV, which is about 6 times higher than that of the BG + BP surface. The BG + IEP surface of superior quality is very smooth (platykurtic) and clean, in contrast to the rough and defective BG + BP surface. The IEP is proposed to be an effective way to simultaneously realize the BG strengthened layer retention and the surface quality improvement.

DOI: https://doi.org/10.1016/j.surfcoat.2022.128292