Creep ductility evaluation of low alloy steels used for steam turbine components

1Cr1Mo1/4V low alloy forging and casing steels exhibited considerable secondary and tertiary stages in the creep tests conducted in the temperature range between 773 and 873 K. The primary stage, though present, was rather negligible at higher temperature ranges. Casting steel showed wedge type cavities which grew as cracks along the grain boundaries. In the case of forging steel, the voids were elliptical and flat which developed during the tertiary stage of creep deformation. Tertiary creep deformation and creep ductility of the two steels investigated have been analysed based on the type of voids developed during the tertiary stage. © 2010 TIIM, India.