Abstract
Quenched and aged ferritic-austenitic two-phase stainless steel was cathodically charged with hydrogen, and tensile properties of the steel have been investigated at room temperature. Results obtained are as follows:
(1) Tensile properties of the steel quenched at 1423 K, 1323 K and 1223 K decrease with increasing hydrogen charging time. In a shorter hydrogen charging time, hydrogen-induced cracking occurs from the ferritic phase near the surface or in the matrix, and the crack growth is suppressed by the austenitic phase. For the steel surfficiently charged with hydrogen, the hydrogen-induced transformation occurs in the austenitic phase, so that the transformed austenitic phase no longer suppresses the growth of crack initiated only in the ferritic phase on the surface.
(2) The hydrogen susceptibility of the steel aged at 748 K and 1023 K increases with increasing aging time owing to the phase transformation, and the tensile properties greatly decrease with increasing charging time compared with those of the quenched steel. The aged steel surfficiently charged with hydrogen is observed to fracture without plastic deformation.
