Additive manufacturing of high-strength crack-free Ni-based Hastelloy X superalloy

Abstract

Laser powder bed fusion (LPBF) is a proven additive manufacturing (AM) technology for producing metallic components with complex shapes using layer-by-layer manufacture principle. However, the fabrication of crack-free high-performance Nibased superalloys such as Hastelloy X (HX) using LPBF technology remains a challenge because of these materials' susceptibility to hot cracking. This paper addresses the above problem by proposing a novel method of introducing 1 wt.% titanium carbide (TiC) nanoparticles. The findings reveal that the addition of TiC nanoparticles results in the elimination of microcracks in the LPBF-fabricated enhanced HX samples; i.e. the 0.65% microcracks that were formed in the asfabricated original HX were eliminated in the as-fabricated enhanced HX, despite the 0.14% residual pores formed. It also contributes to a 21.8% increase in low-angle grain boundaries (LAGBs) and a 98 MPa increase in yield strength. The study revealed that segregated carbides were unable to trigger hot cracking without sufficient thermal residual stresses; the significantly increased subgrains and lowangle grain boundaries played a key role in the hot cracking elimination. These findings offer a new perspective on the elimination of hot cracking of nickel-based superalloys and other industrially relevant crack-susceptible alloys. The findings also have significant implications for the design of new alloys, particularly for hightemperature industrial applications.

Alloy Design and Characterization of γ′ Strengthened Nickel-based Superalloys for Additive Manufacturing

“…In the as-LPBFprocessed nickel-based superalloy, the average cellular interspacing is in the narrow range of 400-600 nm, see e.g. LPBF IN718 [162], LPBF IN625 [179], LPBF Hastelloy X [180,181], LPBF IN939 [182], LPBF IN738LC [86], and LPBF CM247LC [183]. Based on these arguments, the .…”

Current Status of Liquid Metal Printing

“…Despite this, hot cracking was observed in AM Hastelloy X [50,[59][60][61]. Work continues on reducing hot cracking in this specific alloy and other Ni-based superalloys when fabricated by a beam-based AM method [62,63]. Hot cracking, porosity, and balling defects have also been observed in other alloys like aluminum AA6061 and AA7075 and stainless steel alloys [64][65][66].…”

Electrochemical Dissolution Behavior of Nickel-Based Hastelloy X Superalloy at Low Current Densities

“…Due to its great tensile strength and unique advantages in resisting oxidation, corrosion, and high temperature fatigue, Hastelloy X (HX) has been widely used in the fabrication of key engineering components such as gas turbine combustors, transition parts, and exhaust end components [29], [30]. The wrought HX alloy used in this study has a chemical composition (wt.%) of Cr 21.7-Fe 19.3-Mo 9.1-Co 1.3-W 0.46-Si 0.71-C 0.09-Cu 0.26-N 0.01-P 0.025-bal.…”