Influence of interpass temperature on the properties of duplex stainless steel during welding by submerged arc welding process

Abstract

Listen

Translate article

Duplex stainless steels are materials that present high corrosion resistance with high values of mechanical strength, therefore motivating their use in various components in the offshore industry. However, there are major challenges in the welding of these materials in terms of the productivity and quality of the joint produced, considering its extensive use for components of small thickness, such as umbilicals, to those of large thickness, such as salt water injection pipelines. In relation to pipes of small thickness, the gas tungsten arc welding process is successfully used. In thick-walled pipes, the automatic process of submerged arc welding (SAW) has been recently implemented in lines of pre-assembled piping, and this has considerably increased the productivity of the joints produced, though, a great deal of time is required to perform a new weld pass, due to the fact that the maximum interpass temperature needs to be lower than 150 °C. This work presents the results of characterization and the evaluation of corrosion resistance of a welded joint corresponding to DSS UNS S31803, with a wall thickness of 21.4 mm, welded by the gas metal arc welding process in the root and SAW process in the filling and cap passes, employing an interpass temperature between 150 and 290 °C. The results of the characterization of the mechanical properties, chemical composition and corrosion resistance in different regions of the welded joint were compared with those obtained for the base metal of the pipe, as well as with the minimum values required by the project standards. Therefore, this study has made an evaluation of the influence of the interpass temperature in the properties of the joints produced, motivated by a possible increase in productivity in pipe welding.