Investigating Hot Corrosion Behavior of SA 312 TP321H Stainless Steel and SA 335 P5 Ferritic Steel and Their Dissimilar Weldment in Corrosive Salt Environment

摘要

The surface of metals and alloys in contact with a thin film of molten salt at high temperature experiences severe oxidation and hot corrosion. In this study, hot corrosion of A335 P5 ferritic steel and A312 TP321H austenitic stainless steel as base metals and ER309L and ERNiCr-3 as weld metals exposed to two different salt compositions consisting of different proportions of NaCl, Na2SO4 and V2O5 was investigated. The alloy samples were coated with 0.003-0.005 g/cm(2) salt of NaCl-46% Na2SO4 and Na2SO4-60% V2O5 and then experienced twenty hot-corrosion cycles at 650 degrees C for 480 h, and the salt was reapplied in every cycle. The weight gain was investigated, and surface film and composition were studied via scanning electron microscope and X-ray diffraction, respectively. The results showed that 321H steel is more resistant to hot corrosion compared to P5 alloy for both salt compositions. Furthermore, the NiCr-3 weld metal revealed more corrosion resistant in the presence of chloride-containing salt in comparison with 309L.