M. Manikandan

A Comparative Study of Oxidation and Hot Corrosion of Electron Beam Welded Low Alloy Steel and Stainless Steel in Different Corrosive Environments

This paper reports on the performance of Electron Beam Welded (EBW) low alloy steel AISI 4140 and stainless steel AISI 304 in air as well as molten salt environments of Na2SO4-60%V2O5 and K2SO4-60% NaCl at 650(C. The corrosion kinetics has been established by thermo-gravimetric technique during the initial stages. In this work, X-ray diffraction, scanning electron microscopy/energy-dispersive analysis and electron probe micro analysis techniques were used to analyze the corrosion products. It is well observed from the experimental results that the weldments suffered accelerated corrosion in K2SO4-NaClenvironment and showed spalling/sputtering of the oxide scale. Furthermore, corrosion resistance of weld interface was found to be lower than that of parent metals in molten salt environment. It is also inferred from the results that NaCl is the one of the main corrosive species in hot corrosion, involving mixtures of K2SO4-NaCl and which is responsible for internal corrosion attack.

Hot Corrosion Studies on Gas Tungsten Arc Welded AISI 304 and AISI 4140 Dissimilar Joints

Hot corrosion of Gas Tungsten Arc Welded (GTAW) AISI 304 and AISI 4140 dissimilar weldment exposed in air as well as molten salt environment of Na2SO4-60%V2O5 and K2SO4-60% NaCl are discussed. Weight gain studies were done for composite specimens containing both weld metal and heat-affected zone. The results indicated that the specimens were more corroded in molten salt environment as compared to air oxidation. Also weld interface of the samples showed more attack than base metals.