Welding duplex stainless steels: A review of current recommendations

Abstract

Recommendations are grade-dependent but vary little within each group with some exceptions. Two major observations are 1) the lower maximum arc energy permitted for the more highly-alloyed grades and 2) the lower minimum arc energy applicable for grades higher in nitrogen. It can also be noted that there is less agreement on recommendations for newer grades compared to older better established. The very recent 24 % Cr LDX 2404 grade was not launched when the questionnaire was distributed and is consequently not listed in Tables 2 and 3. Producers' data suggest similar weldability as for other high nitrogen grades with low or medium alloy content and the use of 2209-type consumables. Where recommendations differ between sources upper and lower values have been included. Specific comments on grades have been included where suitable. Interpass temperatures and arc energies, both higher and lower than those indicated in Table 2, are sometimes used in applications where post-weld solution annealing is applied. Preheating is usually not recommended. However, if welding is performed at temperatures lower than room temperature, it is advisable to preheat to 50-80°C to ensure moisture free joint surfaces. In rare cases preheating to maximum 150°C is used to minimize the risk of cracking when welding thick and/or heavily restrained work pieces with low arc energy to reduce cooling rate and stress levels.