Influence of the boriding thermal cycle of a cladded Inconel 718 layer on both in situ age hardening as well as wear and corrosion behavior

Abstract

Nickel-based superalloys exhibit exceptional suitability for operating in environments characterized by corrosive agents and elevated temperatures. Strategic allocation of this expensive material solely to the functional surface areas yields significant economic advantages. The poor tribological property profile of Inconel 718 can be significantly improved through a boriding process. In this study, the possibility of combining a coating process with boriding technology and in situ heat treatment was investigated. Layers of Inconel 718 were deposited to an austenitic stainless steel using wire-based electron beam cladding (EBC) and subsequently subjected to boriding. Based on results from annealing experiments, boriding treatments were performed at various temperature/time regimens with the aim of inducing in situ age hardening during boriding. The focus was on the investigation of the influence of the temperature/time regime during boriding on the microstructure and hardness, as well as examining the wear and corrosion behavior of the resulting borided layers. The results showed that the desired target hardness range was achieved after in situ aging with all boriding variants. Furthermore, it was demonstrated that boriding significantly improved the wear resistance but decreased corrosion resistance.