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Additive manufacturing of high-strength crack-free Ni-based Hastelloy X superalloy / Richard, Johnston

Additive Manufacturing, Volume: 30, Start page: 100919

Swansea University Author: Richard, Johnston

  • Accepted Manuscript under embargo until: 15th October 2020

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 Ni-based superalloys such as Hastelloy X (HX) using LPBF technol...

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Published in: Additive Manufacturing
ISSN: 2214-8604
Published: Elsevier BV 2019
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa52481
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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 Ni-based 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 as-fabricated 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 low-angle 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 high-temperature industrial applications.
Keywords: Powder bed fusion, nickel-based superalloy, Hastelloy X, cracking, nanoparticle
College: College of Engineering
Start Page: 100919