Study on Normalizing and Tempering Treatment Regime of Homogenization of P92 Weldments

The present research work describes the effect of normalizing and tempering (N&T) treatment on microstructure evolution in various zones of gas tungsten arc-welded (GTAW) P92 pipe weldments.For N&T treatment, P92 pipe weldments are subjected to various normalizing (950-1150C) and tempering (730-800C) temperatures.The effect of varying heat treatment on tensile properties and hardness of P92 pipe weldments are studied for V-groove and narrow-groove weld designs.The effect of increase in normalizing temperature (at fixed tempering temperature) results in increase in strength and hardness, while increase in tempering temperature (at fixed normalizing temperature) results in the decrease in strength and hardness of P92 steel weldments.Creep strength-enhanced ferritic/martensitic P92 steel is considered as a candidate material for the reactor pressure vessels and reactor internals of Very High Temperature Reactor (VHTR).The heterogeneous microstructure formation across the P92 weldments leads to premature Type IV cracking and makes the weldability of P92 steel as a serious issue.The better combination of strength, ductility and microstructure are obtained for the maximum normalizing temperature of 1050C and tempering temperature of 760C.The effect of increase in normalizing temperature (at fixed tempering temperature) results in increase in strength and hardness, while increase in tempering temperature (at fixed normalizing temperature) results in the decrease in strength and hardness of P92 steel weldments.