On High-Temperature Materials: A Case on Creep and Oxidation of a Fully Austenitic Heat-Resistant Superalloy Stainless Steel Sheet

摘要

The creep behavior of AISI 310S stainless steel taken from SAIL’s Salem stainless steel plant has been investigated by constant load tensile creep test at the temperatures of 973, 1023, and 1073 K and loads of 66.6, 74.8, 86.6, and 94.8 MPa. It exhibits steady-state creep behavior in most test conditions. The double logarithm plot of rupture life and applied stress yielded straight lines at all the three test temperatures indicating that power-law creep due to dislocation climb is the operating mechanism of creep deformation. Linear relationship was obtained for plots of logarithm of rupture life against inverse temperature obeying Arrhenius type of temperature dependence with activation energy of 340 kJ/mol. The stress-rupture data yielded a master curve of Larson-Miller parameter. The plot of Monkman-Grant relationship is typical indicating that rupture is controlled by growth of grain boundary cavities. The metallographic examination of crept samples revealed formation of grain boundary voids and cracks leading to intergranular creep fracture. Deformation twins and carbide precipitates were also observed. Oxidation tests were also carried out isothermally at 973 K, 1023 K, and 1073 K in dry air. The plots of mass gain versus square root time were linear at all the three test temperatures obeying parabolic kinetics of oxidation. It was found that scales are well adherent to the substrate. The plot of parabolic rate constant and inverse temperature was linear giving an activation energy value of 210 kJ/mol. The metallographic examination of an oxidized sample reveals duplex types of scales. Finally, rupture properties are compared with that of AISI 600 iron-based superalloy and oxidation weight gain analysis with surface nanocrystalline AISI 310S stainless steel to analyze quantitatively its behavior.