Creep deformation and rupture behavior of 2.25Cr-1Mo steel weldments and its constituents (base metal, weld metal and simulated heat affected zones)

Microstructure across a weldment base metal through transformed heat-affected zone (HAZ) to cast weld metal. HAZ of 2.25Cr-1Mo weldment consists of coarse-grain bainite, fine-grain bainite and intercritical region. These HAZ microstructures were simulated by isothermal heat-treatments. Creep tests were carried out on base metal, weld metal, weldment and the simulated HAZ structures. Creep deformation and fracture behavior of 2.25Cr-1Mo weldments has been assessed based on the properties of its constituents. Coarse-grain bainite with low ductility and intercritical structure with low strength are the critical components of HAZ determining performance of the weldments.