Environmentally assisted crack growth in one-dimensionally cold worked Alloy 690TT in primary water

Environmentally assisted crack growth in thermally treated Alloy 690 cold worked one-dimensionally to the thickness reduction of 25% in primary water was investigated. In the water at 50 °C and dissolved hydrogen (DH) of 2.7–2.9 ppm, the alloy showed a crack growth rate of <2.2 × 10−9 mm/s at a stress intensity factor of 35 MPa√m. In the water at 340 °C, stress corrosion crack growth rate of <1 × 10−8 mm/s was observed in the alloy over a DH range of 0.37–2.6 ppm. Further, it was found that hydrogen could promote SCC growth when increasing DH from a very low level.

► Cold working caused grain boundary damage in Alloy 690TT.
► Extremely low SCC growth in Alloy 690TT in deaerated primary water at DH = 0 ppm.
► Introducing DH to the deaerated primary water promoted SCC growth.
► DH effect on SCC growth in Alloy 690TT in primary water is statistically insignificant.
► Cold worked Alloy 690TT can have a moderately high resistance to both SCC growth and LTCP in primary water.