High-Temperature Oxidation Behavior of GH5188 Superalloy Foil and Its Effect on Tensile Performance
摘要
In this study, the oxidation behavior of a 0.3 mm thick GH5188 alloy foil in air at 800–1150 ℃ and its effect on tensile properties were investigated. The results showed that the oxidation kinetics of the GH5188 alloy foil followed a parabolic law and exhibited a characteristic a two-stage oxidation process. A protective oxide scale primarily composed of Cr2O3 and MnCr2O4 formed on the foil surface. The consumption of chromium led to the formation and deepening of a carbide-free precipitation zone within the foil. However, thermal stress and growth stress led to stress concentration within the Cr2O3 layer, resulting in spallation of the oxide scale. After oxidation, strip-like precipitates interconnected at grain boundaries, forming a network structure, while fine granular precipitates were diffusely distributed within the grains. The room temperature tensile strength and plasticity of the alloy foil decreased significantly. The tensile strength and elongation of the initial state alloy foil are 1045.7 MPa and 66.4%, respectively. After oxidation at 1150 °C for 50 h, the tensile strength and elongation of the specimen decrease to 888.7 MPa and 35.6%. The fracture exhibited brittle fracture features due to the network structure within the matrix. Additionally, the tensile properties at high temperatures further deteriorated. After oxidation at 1150 °C for 50 h, the high-temperature tensile strength and elongation of the specimen decrease to 516.2 MPa and 30.4%. The deterioration of high-temperature tensile properties was related to stress concentration at oxidation-induced voids.