ENVIRONMENTALLY ASSISTED CRACKING OF NICKEL ALLOYS IN AQUEOUS SOLUTIONS CONTAINING BICARBONATE AND CHLORIDE

NATALIA S. ZADOROZNE; MABEL C. GIORDANO; ALICIA E. ARES; RICARDO M. CARRANZA; RAUL B. REBAK

Pittsburgh, PA, Estados Unidos

Congreso; MATERIALS ISSUES IN NUCLEAR WASTE MANAGEMENT IN THE 21ST CENTURY. MS&T 2014; 2014

MS&T

It was reported in 2002 that Alloy C-22 (N06022) suffered environmentally assisted cracking during slow strain rate tests in aqueous solutions simulating concentrated ground waters. It was later reported that the anion that was responsible for the cracking was bicarbonate and that chloride enhanced the cracking while in presence of bicarbonate. Cracking only occurred at a high anodic applied potential in the proximity of +400 mV SCE and at temperatures higher than approximately 65°C. It was not clear then which element in C-22 was responsible for the environmental cracking. A program was set to study six alloys (Alloy 201, B-3, Ni-20Cr, 600, 800H and C-22) with different amounts of nickel, chromium, molybdenum and iron to determine if a relationship existed between cracking and alloy composition. Current results show that, under the tested conditions, only C-22 shows a clear evidence of environmental cracking.Electrochemical and slow strain rate tests continue.