The Influence of δ-Phase on the Environmentally Assisted Cracking Resistance of an Additively Manufactured Nickel-Based Superalloy

Published

November 22, 2023

Author(s)

Mark R. Stoudt, Richard E. Ricker

Abstract

The combination of strength, corrosion resistance, and excellent weldability makes IN625 an attractive alloy for additive manufacturing (AM) applications, but the processing conditions of AM generate considerable residual stresses, compositional gradients, and microstructural heterogeneities that may have a detrimental influence on properties and the performance. Resistance to environmentally induced cracking resistance is a property that is of particular concern for many applications within the petroleum and natural gas (PNG) industries. To evaluate the influence that AM fabrication may have on this property, AM and wrought processed samples were given essentially identical heat treatments and tested in tension at slow strain rates in an acidified chloride environment under controlled potential (hydrogen fugacity) and freely corroding conditions. The results revealed that the microstructure created by solidification during AM processing had a deleterious influence on mechanical properties and significantly increased cracking when hydrogen was introduced into the metal. This difference is attributed primarily to the presence of -phase in the AM processed samples. This evaluation also demonstrated that after the application of additional thermal processing (e.g., hot isostatic pressing, HIP), the AM solidification microstructure and microsegregation were eliminated resulting in a more homogeneous microstructure that reduced the density and severity of the interactions between the hydrogen, -phase particles, incoherent boundaries, and hydrostatic stress. It is concluded that post-build heat treatments can be designed that will enable AM parts to perform as well as wrought components. Considering that the starting AM microstructure is significantly different from wrought, a different heat treatment protocol will be required.

Citation

Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science

Volume

55

Issue

1

Pub Type

Journals

Download Paper

https://doi.org/10.1007/s11661-023-07252-0

Local Download

Keywords

Additive manufacturing, Nickel-based superalloy, Mechanical performance, Hydrogen embrittlement, Environmentally assisted cracking, Crack propagation resistance

Citation

Stoudt, M. and Ricker, R. (2023), The Influence of δ-Phase on the Environmentally Assisted Cracking Resistance of an Additively Manufactured Nickel-Based Superalloy, Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science, [online], https://doi.org/10.1007/s11661-023-07252-0, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=936480 (Accessed April 27, 2024)