SCC of Alloy 690 in High Temperature Water

Alloy 690, of various microstructures and types of cold work, was tested in representative pressurized water reactor primary water at 340 and 360C. Intergranular cracking was observed on Alloy 690 at constant stress intensity factor (no cycling) and with "gentle" cyclic loading.  Crack growth rates in some cases were in the range of 1 to 10 x 10-9 mm/s, but growth rates as high as 7 x 10-7 mm/s were observed in Alloy 690 with microstructural banding and 1-dimension cold rolling that was tested in the S-L orientation.