Progress in weldability research of super and hyper duplex stainless steels

Super duplex stainless steels (SDSSs) and hyper duplex stainless steels (HDSSs), with more alloying elements content, are more corrosion resistant than the standard grades. Progresses of research works on weldability of SDSSs and HDSSs in recent years are reviewed in this paper. If proper heat input is provided, SDSSs and HDSSs can be welded with most fusion welding processes, while tungsten inert gas welding is the most popular process. SDSSs and HDSSs are more prone to secondary phases precipitation than the standard and lean grades, and heat input for SDSSs and HDSSs welding is restricted to a smaller range. Matching filler materials are usually recommended for SDSSs and HDSSs welding, rather than Ni-riched ones for standard and lean grades. Nitrogen addition in shielding gas is always beneficial. Post weld heat treatment with slow cooling rate will be harmful. Hot cracking tendency of SDSSs and HDSSs joints is not high, but sometimes they can suffer from hydrogen induced stress cracking.