Pulsed current gas metal arc welding of P91 steels using metal cored wires

A detailed experimental study was undertaken to examine the suitability of pulsed current gas metal arc welding of 12 mm thick P91 steels in groove joint configurations with metal cored filler wire. Both the single and multipass welds showed satisfactory bead morphology, tensile strength and toughness especially at higher groove angles of 60° and 75° for the selected range of welding current and speeds. The weld metal compositions showed considerably high presence of Ni, Mn and Si with little loss of other alloying elements. The weld properties were primarily affected by the heat input per unit length of weld and the groove angle. The maximum ultimate tensile strength and toughness of the welds were found to be around 845 MPa and 125 J, respectively, for a heat input of 1.38 kJ/mm and a groove angle of 75°. The use of metal cored filler wires could enhance the welding speed by 20% and filler wire deposition rate by 42% compared to that with the solid wires. Overall, the present study showed that the pulsed current gas metal arc welding of medium to high thickness P91 steels using metal cored filler wires could provide higher deposition rate and welding speed, and enhanced weld bead properties in comparison to solid wires.