TWI Industrial Member Report Summary 63/1978
By J Honeycombe and T G Gooch
The effects of welding on the corrosion and mechanical properties of a duplex stainless steel containing 25%Cr-5%Ni-Cu-Mo have been examined as part of a wider study on the weldability of recently developed stress corrosion resistant stainless steels.
Butt welds were prepared in 13 and 1.7mm thick material using a range of processes and consumables. Susceptibility to intercrystalline attack was evaluated by Strauss and potentiostatic test methods for both thicknesses. Tensile, Charpy, and COD tests were carried out on the 13mm material.
Susceptibility to intercrystalline attack on welding was observed in both heat-affected zone and weld metal. However, the results indicated that the material could be welded without inducing intercrystalline attack in service, with austenitic consumables being preferred.
Transverse joint tensile strengths were comparable with that of the parent material. The toughness levels obtained for HAZs and weld metal were generally below the parent material properties, but remained reasonably high at OoC and above, as appropriate to probable service duties.
The steel showed less propensity for ferrite formation and grain growth at high temperatures than other duplex steels studied previously, but, overall, welding had similar effects in all the duplex materials concerned.