High-temperature creep behavior and microstructural evolution of an 18Cr9Ni3CuNbVN austenitic stainless steel

The creep properties of an 18Cr9Ni3CuNbVN austenitic stainless steel have been investigated at temperatures ranging from 923 to 1073 K and stresses from 120 to 250 MPa. The rupture lives ranged from 10 to 20,105 h. The stress dependence of the minimum creep rate obeyed a power law, with stress exponents ranging from 6 to 8.6. The activation energy was determined to be 460 to 485 kJ/mol/K. The microstructural evolution during the creep test was investigated. The V-rich Z-phase and metallic Cu precipitates began to precipitate in the middle of the creep deformation, resulting in an increase of the creep strength, while only Nb-based MX precipitates were present from the beginning of the high-temperature creep test.