A Study on Unification of Welding Consumables in Construction of Chemical Cargo Tanker Made of Duplex Stainless Steel: Evaluation of Static Strength of Welded Joint

Abstract

Abstract Austenitic stainless steels such as SUS 316 LN and austenitic stainless clad steel are used in cargo holds of chemical tankers owing to their corrosion resistance. Recently, the use of duplex stainless steels has been increasing, owing to their better strength and corrosion resistance and lower content of expensive Ni, compared with those features of austenitic stainless steels. However, few duplex stainless clad steels have been approved by classification bodies. Furthermore, the application of duplex stainless steel is not yet mainstream as hull structural materials because a stable supply market has yet to be established. Therefore, when applying cladding steel to construction of chemical tankers, austenitic stainless clad steel is often used at present. The duplex stainless steel and the austenitic stainless clad steel are mixed at construction factories; hence, there is a risk of misuse of welding consumables. If misuse is suspected, it is not possible to judge the erroneous use from visual inspection after construction; therefore it is necessary to uniformly remove the weld and re-weld. However, if universal welding consumables were identified, this might avoid the problems of misuse and simplify the procurement of welding materials. In this paper, we report on our studies to verify welding consumables for use in the hull structures, involving a mixture of duplex stainless steel and the austenitic stainless clad steel. The static strength of the welded joints is a particular focus of this study, from which we confirmed the validity and limitations of welding consumables.