HOT CORROSION & AQUEOUS CORROSION STUDIES ON FRICTION WELDED DISSIMILAR METALS

Abstract

Understanding the corrosion behaviour of weldment at elevated temperatures and in aqueous medium has become an object of scientific investigation recently. Investigation has been carried out on friction-welded AISI 4140 and •AISI 304 under molten salt of K2SO4 environment at 900° C under cyclic condition. The resulting oxide scales in the weldment have been characterized systematically using surface analytical techniques. Scale thickness on low alloy steel side was found to be more and was prone to spalling. Aqueous corrosion study has been carried out on friction-welded AISI 4140 and AISI 304 in 3.5% NaCI + distilled water solution in both static and accelerated medium at room temperature. The resulting corrosion product in the weldment has been characterized systematically using surface analytical techniques. The corrosion product on 4140 low alloy steel side found more. Weld region has been found to be more prone to degradation than base metals due to inter diffusion of element across the interface and the formation of intermetallic compound.