MICROALLOYING DESIGN FOR REACTOR PRESSURE VESSEL (RPV)

Microalloying technology is widely used in the steel industry to improve a steel's mechanical properties. This perspective comments on current Ti, Nb and V microalloying additions to plate and forging steels used for the fabrication of reactor pressure vessels. The critical microalloying element for prior austenite grain size control is Ti and versions of a steel containing insufficient TiN microalloying additions are likely to experience excessive grain growth in the regions of a weldment close to the fusion boundaries. Some examples of experimental evidence of prior austenite grain coarsening in non-microalloyed RPV steels are shown.