Creep properties of austenitic stainless-steel weld metals

The creep behavior of two austenitic stainless-steel weld metals was investigated. Two AISI 316L stainless-steel base plates were welded together using the submerged arc-welding process. Creep tests were carried out on the welds at constant load, over a stress range of 100 to 400 MPa, and in the temperature range of 600 to 700 degreesC. The relationships between stress and minimum secondary creep rate at a constant temperature were obtained with Norton's law. The results showed that AISI 347 weld metal presented a higher creep resistance with lower values of the minimum strain rate, and, consequently, it exhibited a longer life before rupture than AISI 316L weld metal. However, this weld metal showed a lower ductility value than AISI 316L weld metal. The weld-metal microstructure survey, performed before and after the creep testing, has shown different amounts of delta ferrite, which was strongly dependent on time, temperature, and stress level.