Influence of grain size on isothermal oxidation of Fe-33Ni-19Cr alloy

Abstract

This research study describes the influence of grain size on isothermal oxidation of Fe- 33Ni-19Cr alloy. The Fe-33Ni-19Cr alloy plate was cut into desired dimension and undergone heat treatment of 3 different temperatures namely 1000oC, 1100oC and 1200oC for 2 hours of soaking time followed by water quench to vary the grain size of alloy. This alloy was then ground by using several grit of sand paper as well as weighed by using analytical balance and measured by using vernier calipers before oxidation test. The heat treated Fe-33Ni-19Cr alloys were isothermally oxidized at 800oC for 150 hours. The characterization on oxidized samples were carried out using optical microscope, scanning electron microscope and energy dispersive x-ray, x-ray diffraction and Vickers hardness. The results shows that, increasing the heat treatment temperature will increase the average grain size which was heat-treated at 1000oC shows minimum weight gain and lower oxidation compared to alloys heat-treated at 1100oC and 1200oC. Alloy heat-treated at 1000oC shows continuous oxide layer formed on the surface, while alloy heat-treated at 1200oC indicated oxide spallation. Besides that, phase analysis shows that the oxidized sample formed several oxide phase.