Evaluation of tensile properties of various regions of creep exposed dissimilar weld joint using miniature specimen testing

Strength variations in various regions of a dissimilar weld joint made between 316LN stainless steel (SS) and P91 steel after creep exposure at 550 degrees C and stress of 200 MPa was estimated using automated ball indentation (ABI) test. The ABI results were used to derive equivalent uniaxial tensile flow behaviour using established correlation factors. A comparison of the results obtained in the creep tested and post weld heat treated (PWHT) samples showed loss of strength in the P91 steel side. It was observed that, creep exposure under this testing condition strengthened the 316LN SS side of the weld joint. ABI derived results showed that, the inter critical-heat affected zone (IC-HAZ) of P91 steel is the weakest region across the weld after creep exposure. The narrow IC-HAZ created a strain constraint which caused the specimen to fail in the P91 steel base metal region.

Automated summary

Strength variations in a dissimilar weld joint made between 316LN stainless steel (SS) and P91 steel after creep exposure at 550 degrees C and stress of 200 MPa were estimated using automated ball indentation (ABI) test. Results showed that the creep exposure strengthened the 316LN SS side but caused a loss of strength in the P91 steel side. The ABI-derived results indicated that the intercritical-heat affected zone (IC-HAZ) of P91 steel was the weakest region across the weld after creep exposure.