Abstract
The stress corrosion cracking (SCC) of SUS 310S steel single crystals was investigated by the slow strain rate technique. The smoothed specimens oriented for [001], [101] and [111] were prepared, and each susceptibility to SCC was evaluated from the nominal stress-strain curves in a boiling 42% MgCl2 solution at 416K. The results indicated that the transgranular cracks occurred at the strain rate below 2.38×10-5S-1, and the tensile strength and elongation decreased with decreasing strain rate. The fracture surface of which the appearance was changed by the tensile axis orientation, was formed by the crack growth along ‹110› direction on {100} plane. The susceptibility index to SCC defined by comparing with the nominal stress-strain curves in noncorrosive oil decreased with decreasing strain rate, whereas it was independent of tensile axis orientation. With a longer time to fracture (a lower strain rate), the normal stress to the (001) crack plane nearly became coincident with that on the threshold of SCC obtained by the constant load technique. This fact demonstrates that the susceptibility to crack growth is strongly controlled by the normal stress to the crack plane.
