Effect of Oxide Formation on SCC Arrest Behavior at the Fusion Line Between Alloy 182 Weld and Low Alloy Steel Based Metal

Abstract

This study was carried out to clarify the SCC arrest behavior at the fusion line between Alloy 182 weld and low alloy steel based metal in distilled water under high temperature and high pressure conditions. The specimen used was low alloy steel based metal overlaid with Alloy 182 weld. CBB test was conducted in the autoclave at the temperature of 288°C, the pressure of 8 MPa, the electric conductivity of introduced water with less than 10 μS/m and dissolved oxygen concentration with 8 ppm. The results of CBB test were that all cracks were arrested at the fusion line and sphere-shaped oxide on low alloy steel based metal side were found. According to the relationship between the weld thickness of Alloy 182 and the oxide size, the larger weld thickness of Alloy 182 the larger the oxides become. It suggests that the galvanic effect caused by difference of potential between Alloy 182 weld and the low alloy steel based metal may have affected the results.