Environmental degradation of Alloy 600 and welded filler metal EN82 in an elevated temperature aqueous environment

The stress corrosion cracking (SCC) behavior of Alloy 600 and welded nickel base filler metal EN82 in high temperature water was investigated. A regression model was developed to show the effects of stress and temperature on SCC initiation for Alloy 600 tubing. An activation energy of 50.6 kcal/mole and a stress exponent of -5.7, applicable to these heats of low temperature mill annealed tubing, were determined from the regression analysis. Data are also presented on the SCC behavior of other classes of materials, including low temperature thermally treated tubing, hot worked and annealed ring forgings, and EN82 weld metal in relation to the tubing data