Crack elimination of laser powder directed energy deposition Inconel 738LC using in-situ addition of Inconel 718: A comprehensive study on the mechanical and corrosion resistivity properties

Abstract

The additive manufacturing (AM) of Inconel 738LC has faced challenges because of its non-weldability and susceptibility to cracking. This paper presents a novel strategy for producing crack-free Inconel 738LC alloy by using an in-situ alloying method combined with height-dependent process parameter optimization for laser powder directed energy deposition (LP-DED) processes. Upon successful production of samples, comprehensive microstructural, mechanical, and chemical analyses were conducted to evaluate the tensile, hardness, and hot corrosion behavior of the manufactured samples. The properties of the alloyed sample were compared with those of pure Inconel 738LC and Inconel 718 alloys to evaluate the effect of in-situ alloying. The results show that incorporating approximately 20 % Inconel 718 into Inconel 738LC enhances its manufacturability while preserving the excellent properties of the base material. The microstructure of the alloyed samples showed a superposition of the pure Inconel 738LC and Inconel 718 alloys. Furthermore, the alloyed samples exhibited a high yield strength of 955 MPa with an elongation at break higher than 8 %. The hot corrosion test results also revealed a significant improvement in the corrosion resistance of Inconel 738LC by alloying with Inconel 718 due to the elimination of cracks and the improvement of Cr content.