External and Internal Cracking Caused by Heat Treatment in Laser Powder Bed Fusion‐Fabricated Inconel 738LC Components
Source abstract
Abstract
Heat treatment‐induced cracking in laser powder bed fusion (LPBF)‐fabricated components of a nickel‐based superalloy, Inconel 738LC, is systematically investigated under various heat‐treatment conditions. Metal additive manufacturing of heat‐resistant nickel‐based superalloys is a key manufacturing technology for advancing heat engines in aerospace propulsion systems and industrial machinery. In this study, cracks in LPBF‐fabricated Inconel 738LC components are characterized after heat treatment at 873–1513 K. The observed cracks are classified into two groups. One group comprises external cracks along high‐angle grain boundaries between columnar grains, originating from the bottom or top surfaces. These external cracks begin to propagate during the heating stage at around 1023 K. The other group consists of internal cracks that initiate at flaws such as gas pores and solidification cracks formed during the LPBF rapid solidification process. Heat‐treatment conditions are found to influence internal cracking through stress relaxation, strain induced by precipitation, and liquation cracking along grain boundaries. Microstructures after heat treatment are characterized by L1 2 (γ′) intermetallic precipitates dispersed in a face‐centered cubic (γ) matrix and grain boundary carbides, including chromium‐rich M 23 C 6 carbides and titanium‐rich MC carbides. Finally, crack‐free heat‐treated LPBF components are fabricated using a modified LPBF laser scan strategy.
Source: crossref · Quality: baseline
Research context
OpenAlex topics: Additive Manufacturing Materials and Processes · High Entropy Alloys Studies · High Temperature Alloys and Creep
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Research Center for Structural Materials National Institute for Materials Science Tsukuba Ibaraki Japan
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