HOT CORROSION STUDIES ON DISSIMILAR WELDED STEEL ALLOYS UNDER SERVICE ENVIRONMENT

Abstract

The study of dissimilar weldments used in high service temperature applications has gained importance in the recent past years. Combination of High strength Low Alloy Steel (HSLA) and Austenitic Stainless steel is usually preferred for tubing applications in Heat exchangers, Boilers and Off shore oil rigs because of its good weld ability, Low cost and high resistance to stress corrosion cracking. By taking into account, temperature conditions and the corrosive environments encountered in industries, we can tell that 14SLA and austenitic Stainless steel makes the best available options to construct a transition joint. High strength Low Alloy Steel (1-ISLA) & Austenitic Stainless steel welded joint is widely used in plant fossil-fired power plants, 1-leat exchangers, Off-shore oil rigs where this joint is most likely encountered with highly corrosive environments. HSLA is best suited for these applications because of its corrosion resisting & good mechanical properties while on the other hand Austenitic Stainless steel possess good weld ability, High corrosion resistant properties which makes it a suitable selection for high temperature applications. Various problems are encountered during the service and during dissimilar welding of these two steels because of their vastly different physical, thermal, mechanical and metallurgical characteristics. In view of the above, the present study focuses attention on Shielded Metal Arc Welding (SMAW), Pulsed Gas Metal Arc Welding (P-GMAW) and Tungsten Inert Gas Welding (TIG)