Effect of Alloyed Mo and W on The Corrosion Characteristics of Super Duplex Stainless Steel Weld

Abstract

The corrosion behavior of super duplex stainless steel (SDSS) weldments which depend on Mo and W content has been studied. In order to compare the electrochemical characteristics depending on the change in the content of Mo and W, Anodic Polarization Tests were conducted in the 3.5%NaCl solution and 1M H2SO4 solution before observing the changes in the microstructure. The observation results of the microstructure showed that the fraction of 6-ferrite increased as Mo was partially substituted by W, and y grew with a constant directional property. Also, the analysis results of the phase after aging the specimens for 30 minutes at 800 0C showed that there was less ϭ phase precipitation in the W added specimen than that of only Mo added. Though the results of potentiodynamic polarization test showed no difference in corrosion resistance in as-weld state- in the polarization test after aging treatment- the W added specimen showed superior corrosion resistance to that of only Mo added. As a result of analyzing the microstructure after the polarization test- pitting occurred in a Cr and Mo depleted zone around o phase.