The use of super duplex stainless steels plates for an increasing number of applications creates a need for improved welding practices. This requires an extensive study of super-duplex weld properties and the determination of the optimised welding conditions but also the development of new filler materials and the use of less expensive welding processes.

Welding super-duplex materials with an austenitic-ferritic consumable is necessary when a weld with matching tensile strength is required, for instance for pressure vessel fabrication or when a solution annealing heat treatment is made after welding. But this puts a limit to other properties of the super-duplex weld metals such as compactness, toughness at low temperature or pitting corrosion resistance. For instance, over-alloying (Mo, Cr) of the existing super-duplex filler materials could not be done without risking deleterious precipitations of intermetallic phases.

The aim of this paper is to introduce Ni alloyed filler materials recently developed or improved and now industrially used for GMAW or GTAW of UR 52N⁺ super-duplex plates. The properties of UR 52N⁺ welds using several Ni alloy filler materials and the new PHYWELD NCM, a Ni – 22 Cr 9 Mo Nb free filler metal, are described in this paper. When compared to the properties of the welds made with super-duplex filler metal, a better corrosion resistance, a better toughness at low temperature and a less susceptibility to porosities are achieved for the welds using Ni alloy without niobium addition filler metal. But the strength of the Ni alloy weld metal is lower than that of the super duplex plate. However welding procedure qualification results for the transverse tensile test generally meet the requirements of construction codes.

Finally, industrial references of constructions using super duplex plate welded with Ni alloy without niobium addition are now available, particularly for pollution control equipment, where productive welding methods such as MIG or pulsed MIG are normally selected.