Deformation Mode and Microstructure on Stress Corrosion Cracking Path and Kinetics in High Temperature Water Environments

Effects of water chemistry on stress corrosion cracking of 316NG weld metals in high temperature water

“…The results are similar to those obtained in cold worked 316L stainless steel and 316L HAZs. 10,11,[19][20][21] CGRs for specimen HTW2 at 7 ppm DO and 11 ppm DO were lower than that at 2 ppm DO. The CGR obtained during the step HTW2C6 in 1 ppm DO water was significantly higher than that in 11 ppm DO water.…”

“…The results imply that there could be an incubation period before the onset of steady state crack growth, even when the specimen had been precracked by fatigue in air and in situ precracked in high temperature water with stepped increases in load ratio R. SCC incubation periods in the SCC steps after in situ precracking have been observed in previous experiments for cold rolled or warm rolled low carbon stainless steels and another heat of 316NG weld HAZ and weld metal in high temperature water environments. [10][11][12][13][17][18][19][20][21] It has been proposed that the transition from transgranular cracking during in situ precracking to intergranular or interdendritic cracking during SCC could be one of the important factors for the occurrence of SCC incubation periods. Other factors such as evolution of local environment and maturing of specimen surface may also have an effect.…”

“…The effects of dissolved oxygen concentration or electrochemical potential on oxidation kinetics and crack growth behaviour of stainless steels in high temperature water environments have been investigated. [10][11][12][13][17][18][19][22][23][24][25][26] CGRs of sensitised 304SS and solution annealed non-sensitised stainless steels increased monotonically with electrochemical potential, which tended to reach a plateau at high DO concentrations where corrosion potential and CGR were not sensitive to DO in this range. Decreasing electrode potential moderately inhibited crack growth of prior hardened austenitic stainless steels in high temperature pure water, which was less significant than that of sensitised 304 stainless steels and as solution annealed low C stainless steels in similar environments.…”

“…[2][3][4][5] SCC growth behaviour of 316L HAZs, 316NG HAZs and weld metals in simulated BWR environments was investigated. [5][6][7][8][9][10][11][12][13] For stainless steel weld metals, the effects of solidification processes, low temperature aging on microstructure, mechanical properties and SCC behaviour have been investigated by Abe et al, Kim and Ballinger and Negishi et al [14][15][16] In actual plants, the ferrite fraction and solidification mode could be different depending on the chemical compositions of filler metals, welding procedures and locations of weld metals in welds. In the present research, SCC growth rates in 316NG weld metals with different ferrite contents were measured in 288uC high purity water with various dissolved oxygen concentrations.…”