Effect of heat treatment on the microstructure characteristics and microhardness of a novel γ′ nickel-based superalloy by laser powder bed fusion
Journal article, 2021

The fabrication of gamma prime (γ′) strengthened nickel-based superalloys by additive manufacturing (AM) techniques is of huge interest from the industrial and research community owing to their excellent high-temperature properties. The effect of post-AM-processing heat treatment on the microstructural characteristics and microhardness response of a laser powder bed fused (LPBF) γ′ strengthened nickel-based superalloy, MAD542, is systematically investigated. Post-processing heat treatment shows the significant importance of tailoring the γ′ morphology. With insufficient solutioning duration time, coarse γ′ formed in the interdendritic region heterogeneously, due to the lack of chemical composition homogenization. The cooling rate from the super-solvus solutioning plays an important role in controlling the γ′ size and morphology. Spherical γ′ is formed during the air cooling while irregularly shaped γ′ formed during the furnace cooling. The following aging heat treatment further tunes the γ′ morphology and γ channel width. After two-step aging, cuboidal γ′ is developed in the air-cooled sample, while in contrast, bi-modally distributed γ′ is developed in the furnace cooled sample with fine spherical γ′ embedded in the wide γ channel between coarse irregular shaped secondary γ′. More than 90% of the grains recrystallized during solutioning treatment at the super-solvus temperature for 30 min. The rapid recrystallization kinetics are attributed to the formation of annealing twins which significantly reduced the stored energy. Microhardness responses from different heat-treated conditions were examined.

Recrystallization

LPBF

Nickel-based superalloy

Gamma prime γ′

Heat treatment

Author

Jinghao Xu

Linköping University

Fiona Schulz

Chalmers, Industrial and Materials Science, Materials and manufacture

Ru Lin Peng

Linköping University

Eduard Hryha

Chalmers, Industrial and Materials Science, Materials and manufacture

JJ Moverare

Linköping University

Results in Materials

2590048X (eISSN)

Vol. 12 100232

Subject Categories

Energy Engineering

Food Engineering

Metallurgy and Metallic Materials

DOI

10.1016/j.rinma.2021.100232

More information

Latest update

4/7/2022 1