Improving mechanical properties of P91 and IN617 dissimilar weld joints for advanced ultra super critical power plants by buttering technique

To improve the mechanical properties of ferritic steel and nickel superalloy, while maintaining economic symmetry, this investigation is performed on fabricating dissimilar metal welds for advanced ultra-supercritical (AUSC) boilers, with a buttering technique. The present work compares a dissimilar weld of IN617 alloy and P91 steel with and without buttering by multipass gas tungsten arc welding for mechanical properties variations, creep strength at elevated temperature, and microstructural evolution. Thin layers of buttering material are applied at the ferritic end, followed by the closure weld consisting of welding a second member to a butter layered component. Further, significant improvement in mechanical properties (tensile strength, toughness, and hardness) and creep rupture life (though the failure remains ductile characterized by dimples variations) 2 to 3 times longer has been found with buttering in contrast with no buttering.

Automated summary

This study investigates the fabrication of dissimilar metal welds for advanced ultra-supercritical boilers, using a buttering technique. It is found that the mechanical properties and creep rupture life can be significantly improved by buttering, especially when thin layers of buttering material are applied at the ferritic end.