Experimental and chemo-mechanical analysis of hot corrosion influence on creep properties of DD6 single crystal superalloy in molten NaCl salt. (1st February 2022)

• Record Type: Journal Article
• Authors: Liu, H.; Wang, X.M.; Liu, P.Y.; Zhao, Z.N.; Yang, W.Z.; Li, L.
• Is Part Of: Engineering fracture mechanics. Volume 260(2022)
• Publication Date: 2022-02-01
• Subjects: Hot corrosion -- Creep -- Mechanical properties -- Nickel-based single crystal superalloys -- Chemo-mechanical analysis; Fracture mechanics -- Periodicals; Rupture, Mécanique de la -- Périodiques; Fracture mechanics; Periodicals; 620.112605
• DOI: 10.1016/j.engfracmech.2021.108194
• Languages: English
• ISSNs: 0013-7944

Abstract

Highlights: The effect of hot corrosion on the creep properties of Nickel-based single crystal superalloy is assessed in order to reflect the real damage mechanism of turbine blade serving in marine environment. The fracture mechanism of Nickel-based single crystal superalloy is greatly changed under the effect of molten NaCl. The existence of molten NaCl plays a vital role on the distribution of metal elements. A chemo-mechanical coupling model is used to assist the understanding of the failure mechanism of the salt-coated specimen. Abstract: The creep tests of specimens coated with NaCl salt were carried out to investigate the influence of hot corrosion on the creep properties of DD6 under 980 °C and 275 MPa. Bared specimens were also studied to make comparison. Creep lives of the salt-coated specimens are much lower than those of the bared specimens. Metallographic analysis of the fracture surface shows that creep-rupture of the salt-coated specimens is caused by a main tearing ridge rather than the connection of dimples in the bared specimens. Directional diffusion of metallic elements, i.e. Cr, Ta, and W, happens in hot corrosion-creep test due to the chemical gradient. The location of Al-rich region in the salt-coated specimen is found along the path of crack propagation. The microstructure evolution of γ/γ′ is different between the salt-coated specimens and the bared specimens. A chemo-mechanical coupling model was used to assist the understanding of the failure mechanism of the salt-coated specimen. The simulation results prove that the anodic concentration is a basic factor for the appearance of the main tearing ridge and Al-rich region in the salt-coated specimen. These findings can be helpful to understand the mechanical properties of Nickel-based single crystal superalloys in marine environment.