Hydrogen Effects in Equiatomic CrFeNiMn Alloy Fabricated by Laser Powder Bed Fusion

Xuan Yang,Yuriy Yagodzinskyy,Simo-Pekka Hannula,Joonas Lehtonen,Lauri Kollo,Eryang Lu,Yanling Ge

doi:10.3390/met11060872

Xuan Yang, Yuriy Yagodzinskyy + Show 5 more

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https://doi.org/10.3390/met11060872

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Abstract

This study investigates the effects of laser powder bed fusion (LPBF) on the hydrogen uptake of the face-centered cubic (FCC) equiatomic CrFeNiMn multicomponent alloy after cathodic hydrogen charging (HC). Hydrogen desorption was evaluated using thermal desorption spectroscopy (TDS), and microstructural changes after the TDS test were examined. Results reveal that the amount of hydrogen absorbed by LPBF CrFeNiMn alloy was significantly higher than that in pulsed electric current sintered (PECS) CrFeNiMn alloy or in conventional 316L austenitic stainless steel. The observations are ascribed to the differences in the amount of hydrogen absorbed by the multicomponent lattice, dislocation densities, width of segregation range at cell walls created by the rapid cooling in LBPF, and vacancies remaining after cooling to room temperature. A hydrogen-charged LBPF transmission electron microscope (TEM) specimen was also characterized. Stacking faults and cracks along the (111)-planes of austenite were observed. Scanning electron microscopy (SEM) of the surface of the TDS-tested samples also indicated hydrogen-induced cracks and hydrogen-induced submicron pits at the grain boundary inclusions.

Highlights

Multicomponent equiatomic alloys, more commonly known as high-entropy alloys (HEAs), typically consist of five or more principal elements contributing to high mixing configurational entropy
We focus on the effects of hydrogen on the microstructure of the as-built selective laser melting (SLM) CrFeNiMn alloy described previously [10]
For comparison, the same set of powder with a particle class size < 200 μm was used to prepare a pulsed electric current sintered (PECS) sample, which was sintered in an FCT HP D 25-2 unit (FCT Systeme GmbH, Rauenstein, Germany), using a 20 mm inner diameter graphite die, holding for one minute at 1110 ◦ C under 35 MPa pressure in Ar atmosphere, and the heating and cooling rate was 100 ◦ C/min

Summary

Introduction

Multicomponent equiatomic alloys, more commonly known as high-entropy alloys (HEAs), typically consist of five or more principal elements contributing to high mixing configurational entropy. This concept breaks through the traditional design framework of alloys, provides numerous possible combinations of elements, and results in extraordinary physical, chemical, and mechanical properties [1]. Cobalt alloying is not the most suitable candidate for nuclear applications due to the activation of cobalt under irradiation. Non-equiatomic Cr18 FeNiMn has been recently studied as a close alternative to the cobalt-containing alloy [6,7] as the potential construction materials for the next-generation nuclear power plants (NPP)

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