Duplex and Super Duplex stainless steels are not normally specified for cryogenic service; nevertheless there is considerable interest in applications requiring adequate toughness in the range 0^oC to about –70^oC. Temperatures in this range are typical of those specified for the offshore and land-based oil and gas systems, either for low temperature service or adiabatic 'blow down' conditions.

In 1991 preliminary information for the super duplex alloy Zeron 100® was presented, largely based on all-weld metal data, and this has been referenced on a number of occasions as representing the state of knowledge with respect to Zeron 100® weldment toughness. In fact, the data given were intended to provide partial transition curves for a number of welding processes and provide a guide as to the toughness which might be expected from different process/consumable combinations.

Since 1991 there has been significant commercial exploitation of the super duplex alloy Zeron 100 and a large number of development, weld procedure and production test pieces have been completed. This in turn has lead to the generation of more toughness data covering the temperature range –20^oC down to –100^oC specifically related to welded joints. At the same time there has been a steady growth in the use of 22%Cr standard duplex stainless steels and the opportunity has been taken to collect welded joint toughness data for a range of welding processes.

This paper presents the collection of data generated since the publication of the '1991' data for a range of the most commonly used welding processes. The data is reviewed in the light of proposed acceptance standards currently being developed from extensive fracture mechanics and large scale testing programmes.