Influence of cooling strategy on microstructure, deformation mechanism and mechanical properties of a nickel-based superalloy

• Published in: Materials characterization Vol. 202; p. 112994
• Main Authors: Ji, Zhiyong, Pan, Xingyu, Jia, Chonglin, Qiu, Chunlei
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.08.2023
• Subjects: Deformation mechanism; Impact toughness; Microstructural evolution; Nickel base superalloy; Stress rupture properties; Microstructural evolution; Impact toughness; Stress rupture properties; Nickel base superalloy; Deformation mechanism
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2023.112994

In this study, the influence of cooling strategy after solution treatment on microstructure and mechanical properties of a novel cast and wrought nickel-based superalloy is studied. It was found that continuous oil cooling (CC) from the solution temperature led to formation of large primary γ' and ultrafine tertiary γ'. Interrupted cooling (IC), which involves furnace cooling from the solution treatment temperature (1080 °C) to a lower temperature (such as 1010 °C, 980 °C or 950 °C) first followed by an interrupted oil cooling, shows significant influence on microstructure. Owing to a short-period furnace cooling, secondary γ' started to form in these interrupted cooled samples and their volume fraction and size increased continuously with decreased IC temperature. In contrast, the volume fraction of tertiary γ' decreased with decreased IC temperature. The CC sample was found to deform mainly by dislocation glide/climb and extension of stacking faults at 650 °C/950 MPa. With increased volume fraction of large secondary γ' in the interrupted cooled samples, deformation became increasingly planar, i.e., the formation of stacking faults and nanotwins increasingly became the dominant deformation mechanisms. The cooling strategy shows no obvious influence on tensile properties and impact toughness but shows significant influence on stress rupture properties. With decreased IC temperature and coarsened microstructure, the stress rupture lifetime continues to decrease. •Two cooling strategies were adopted on a novel cast and wrought nickel-base superalloy.•The cooling strategy shows significant influence on stress rupture properties.•The influence of cooling strategy on microstructure evolution and mechanical properties was further discussed.