EFFECT OF MATERIAL CONDITION ON STRESS CORROSION CRACK INITIATION OF COLD-WORKED ALLOY 600 IN SIMULATED PWR PRIMARY WATER

摘要

The effects of material condition and grain boundarycarbides on stress corrosion crack initiation wereevaluated on a cold-worked Alloy 600 heat in solutionannealed and thermally treated conditions. Stresscorrosion crack initiation responses of these materialconditions were investigated by constant load testing insimulated pressurized water reactor primary coolantenvironments. The direct current potential drop techniquewas used for in situ detection of crack initiation. Byperiodically examining the specimens at test interruptions,evolution of precursor damage including intergranularattack and short cracks was carefully documented andcompared to data previously obtained from unstressedcoupons exposed to the same environment. Resultsrevealed the predominant role of mechanical factors in thedevelopment of precursor damage with no apparentimprovement in stress corrosion crack initiation resistancedue to grain boundary carbides.