Wear mechanism, subsurface structure and nanomechanical properties of additive manufactured Inconel nickel (IN718) alloy

Abstract

Inconel nickel (IN718) superalloy is a cutting-edge material for high temperature applications owing to its superior mechanical properties in both cryogenic and high temperatures. Although the selective laser melting (SLM) processed IN718 superalloy has extraordinary properties, the tribological behavior of this new class of material is unclear. This study aims to explore the tribological behavior and subsurface mechanical properties of SLMed IN718 superalloy with the aid of nanomechanical and structural characterization techniques. The worn subsurface structure was revealed against the mechanical properties of the material using the ball-on-disk contact sliding test. Structural analysis confirmed that the SLMed IN718 superalloy consisted of Fe, Ni, Cr, Nb and Mo elements. EBSD analysis showed that a mixture of equiaxed and columnar grains emerged in <001>, <101> and <111> of SLMed IN718 superalloy. In-situ wear track investigations using 3D profilometer integrated tribometer revealed that its width and depth significantly increased with applied sliding load. Severe abrasive wear occurred at a low load. Under a high load, however, frictional heating brought about plastic deformation and led to increase wear in absence of any significant subsurface damages. The plastic deformation also generated shear-bands in the immediate subsurface and refined the grain structure, which significantly increased the nanohardness and elastic modulus of the deformed material layer.