Open AccessInfluence of microstructure on stress corrosion cracking of mild steel in synthetic caustic-nitrate nuclear waste solution
Author(s) -
Peter Gregory Sarafian
Publication year - 1975
Language(s) - English
Resource type - Reports
DOI - 10.2172/4088159
Subject(s) - stress corrosion cracking , materials science , microstructure , caustic (mathematics) , metallurgy , corrosion , environmental stress fracture , cracking , hydrogen embrittlement , nitrate , stress (linguistics) , composite material , chemistry , linguistics , physics , philosophy , organic chemistry , mathematical physics
The influence of alloy microstructure on stress corrosion cracking of mild steel in caustic-nitrate synthetic nuclear waste solutions was studied. An evaluation was made of the effect of heat treatment on a representative material (ASTM A 516 Grade 70) used in the construction of high activity radioactive waste storage tanks at Savannah River Plant. Several different microstructures were tested for susceptibility to stress corrosion cracking. Precracked fracture specimens loaded in either constant load or constant crack opening displacement were exposed to a variety of caustic-nitrate and nitrate solutions. Results were correlated with the mechanical and corrosion properties of the microstructures. Crack velocity and crack arrest stress intensity were found to be related to the yield strength of the steel microstructures. Fractographic evidence indicated pH depletion and corrosive crack tip chemistry conditions even in highly caustic solutions. Experimental results were compatible with crack growth by a strain- assisted anodic dissolution mechanism; however, hydrogen embrittlement also was considered possible. (auth