2205 Duplex stainless steel is used in many applications in order to take advantage of the alloy’s corrosion resistance and its strength. Application areas include the oil and gas industry and the chemical industry.

25Cr duplex filler, of proof strength ~650 MPa, is increasingly used as filler metal to complete joints in 22Cr duplex parent material, proof strength ~510 MPa to maximise the corrosion resistance of the as deposited weld metal.

The significance of weld metal strength and welding procedure for the corrosion resistance and the toughness of the weld zone in as welded 2205 duplex stainless steel has been examined.

The high temperature HAZ fracture toughness was reduced by using the overmatching filler but that the reduction did not result in brittle failure. The reduction in toughness was found to be related to the weld metal strength, as measured by its hardness. The significance of the high temperature HAZ hardness, in relation to the high temperature HAZ fracture toughness, was not clear although their is probably a similar but less significant relationship between these two when compared to the relationship between the weld metal hardness and the high temperature HAZ fracture toughness. No clear significant variation in microstructure or high temperature HAZ notch toughness was observed.

In the SSCC testing, there was no clear indication of an affect associated with using the overmatching filler. However, the crack morphology changed from 'a large number of small cracks' to 'few but much longer cracks' when using 'high', rather than 'normal', heat input and when tested in NACE solution containing 8% H₂S.

The use of 2507 root pass filler metal improved the CPT of the root side weld zone, when compared to the use of 2205 filler.