Influence of nickel on the toughness of lean duplex stainless steel welds

Three weldments with the nickel contents 1.3, 4.9 and 6.0 wt% were made from 30 mm LDX 2101® plates. The weldments were subjected to tensile, impact and fracture toughness testing. The aim was to evaluate the susceptibility for brittle failure in the weld metal at sub-zero temperatures (°C). The amount of ferrite was higher for the 1.3 wt% nickel weldment compared to the other two which had similar phase composition and mean free ferrite distance. The result from the tensile testing showed that for the weldment with the highest nickel content the ductility remained unchanged with decreasing temperature while the other two weldments became less ductile with decreasing temperature. J-integral based fracture toughness testing showed a significant difference in the susceptibility for brittle failure with higher values for the weldment with 6 wt% nickel than for the others with lower nickel content.