As the deep submersible vehicle is subject to severe conditions in deep sea, it is essential that the materials used for pressure hull should have performance with regards to fracture toughness, fatigue properties, stress corrosion cracking properties and so on. Especially, the properties to resist the stress corrosion cracking is the most significant problem of the materials for pressure hull.
From this view point, the authors have investigated the stress corrosion cracking of 10Ni-8Co steel and its weld joint for several years and made clear the effect of heat treatment conditions, shielding conditions in GTA welding and fabricational conditions.
The conclusions are that 10Ni-8Co steel is usable as a material for the construction of the pressure hull of the deep submersible vehicle from viewpoint of stress corrosion cracking.