Abstract
A cold-worked stress corrosion-cracking (CWSCC) phenomenon is defined as an insidious failure mechanism caused by the corrosive environment, and residual tensile stressed and crack-susceptible hardening surface due to the cold-working under no applied stress in stainless-steel of nuclear power reactor, duralumin of aircraft, brassware of plumbing and others.We have developed the novel method to prevent stainless-steel CWSCCs that ultrafast femtosecond Ti:Sapphaire laser and free-electron laser peel off the hardening surface having major CWSCC origins of the residual tensile stress and crack- susceptibility more quickly than conductive heat transmission. This differs from existing technologies of shot peening and anticorrosive films coating the surface and others which last only a short and limited period of time. On the contrary, this can be expected the prevention longer than a product life span and almost perpetual one because the fs laser peeling-off removes completely two fundamental origins of the residual tensile stress and susceptibility in the hardening surface.The MgCl2 SCC test in small samples showed that the laser peeling-off method perfectly prevents the crack and the non peeling-off surface exhibits the 100000 cracks per a centimeter square.
