Thickness influence on creep properties for Ni-based superalloy M247LC SX

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2012-07, Vol.550, p.254-262
• Main Authors: Brunner, Martin, Bensch, Matthias, Völkl, Rainer, Affeldt, Ernst, Glatzel, Uwe
• Format: Article
• Language: English
• Subjects: Al-coating; Aluminizing; Applied sciences; Corrosion; Corrosion mechanisms; Creep; Creep (materials); Creep rate; Exact sciences and technology; M247LC SX; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Microstructure; Nickel; Nickel base alloys; Nickel-base superalloy; Scatter; Superalloys; Thickness; Thin-walled
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2012.04.067

► Thickness reduction decreases the creep strength of M247LC SX. ► Aluminized coated specimens show less scattering in creep and is recommended. ► Tests in air have same performance as in vacuum, but different oxide formation. ► Variations in material preponderates much more for thin specimens. ► For turbine blade design the influence of specimen thickness must be considered. The influence of specimen thickness on creep behavior of coated and uncoated specimens was investigated. Creep experiments were carried out on the single crystal Ni-base superalloy M247LC SX at 980°C and 1100°C. Tests were performed at different stress levels for 0.3mm and 1.0mm flat specimens in vacuum and ambient air. A decrease in creep strength with decreasing thickness was observed. Aluminized specimens showed less scatter in creep behavior in terms of both, rupture times and minimum creep rates. If only the initial two-phase area is considered (without interdiffusion zone and coating layer) the influence of specimen thickness on creep behavior were found to be negligible. The results show, that for turbine blade design the influence of wall thickness has to be considered. Thin-walled structures (below 1.0mm) should be aluminized in order to reduce scatter in material behavior and to minimize the influence of oxidation on matrix/γ′-microstructure in order to form γ′ reduced or γ′ depleted zones.