Investigation of high temperature corrosion behavior on 304L austenite stainless steel in corrosive environments

Abstract

In this work, 304L stainless steel samples were exposed at 700 °C for 10hrs in different corrosive environments; dry oxygen, molten salt, and molten salt + dry oxygen. The corrosion behavior of samples was analyzed using weight change measurement technique, optical microscope (OM) and Scanning Electron Microscope (SEM) equipped with Energy Dispersive X-ray (EDX). The existence phases of corroded sample were determined using X-ray Diffraction (XRD). The lowest corrosion rate was recorded in dry oxygen while the highest was in molten salt + dry oxygen environments with the value of 0.0062 mg/cm 2 and -13.5225 mg/cm 2 respectively. The surface morphology of sample in presence of salt mixture showed scale spallation. Oxide scales of Fe 3 O 4 , Fe 2 O 3 were the main phases developed and detected by XRD technique. Cr 2 O 3 was not developed in every sample as protective layers but chromate-rich oxide was developed. The cross-section analysis found the oxide scales were in porous, thick and non-adherent that would not an effective barrier to prevent from further degradation of alloy. EDX analysis also showed the Cr-element was low compared to Fe-element at the oxide scale region.