Properties of High Temperature Oxidation of Heat-resistant Steel with Aluminium and Copper

The research is focused on a novel aluminum and copper-containing heat-resistant steel. The steel was designed by the material performance simulation software JmatPro, performed high-temperature oxidation tests at 650 degrees C and 700 degrees C atmospheric conditions, and analyzed the high-temperature oxidation processes and its mechanisms.The phase transtions and surface morphology of the oxide films were studied using X-ray diffraction (XRD), electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results showed that the equilibrium phase of the test steel is composed of gamma phase and delta phase at 1050 degrees C and tranforms to tempered martensite and delta-Fe mixed structure after heat treatment. The preferential oxidation of Fe and Cr and the internal oxidation of Al occurred during the high temperature oxidation of the test steel. The oxide films were formed with various shape and weak bonding properties after high-temperature oxidation at 650 degrees C. To the contrary, the oxide films more regular and evenly distributed, and has a certain protective effect after high-temperature oxidation at 700 degrees C. The oxide films were divided into two layers, Fe2O3 is main element in the outer layer, the inner layer is mainly consisting the oxide of Cr. However, the addition of Cu element can promote the diffusion of Al and Si elements, which is beneficial to the formation of Al2O3 and SiO2 protective oxide films and excellent in high temperature oxidation resistance.