High-temperature hydrogen sulfide corrosion on the heat-affected zone of the AISI 444 stainless steel caused by Venezuelan heavy petroleum

Abstract

The aim of this study was to evaluate the effect of welding on the corrosion resistance of the heat-affected zone (HAZ) of the AISI 444 ferritic stainless steel in medium containing Venezuelan heavy oil. AISI 444 steel plates were welded through the use of three levels of welding heat input (4, 6 and 8 kJ/cm). Samples were extracted from the welded plates and thermally treated in three different temperatures (200, 300 e 400 °C), while immerged in petroleum for a period of 4 h. Optical microscopy (OM), scanning electronic microscopy (SEM) and energy dispersive X-ray analysis (EDX) techniques were used for the analysis of the surface and transversal section of the joint. Electrochemical trials of cyclic potentiokinetic reactivation of double loop (EPR-DL) were also carried out. It has been concluded that the temperature of treatment has direct influence on the level of material corrosion and that the increase in the welding heat input contributes to a higher level of corrosion.