Precipitation, recrystallization and elemental propositions in micro-alloyed steels

Aim of microalloyed steel has been solid solution strengthening and
precipitation strengthening. Austenitic solid solutions at greater temperature have
produced precipitation during cooling. In vanadium carbonitride (V(C, N)) nitrogen has
major role in precipitation sequence and kinetics. Vanadium diffusion has been rate
controlling in the growth of carbonitride precipitation. Kinetics of static recrystallization
critical temperature (SRCT) has studied to be a function of strain, austenite grain size
and microalloy content of steel. V(C, N) has stated to improve steel properties by ferrite
formation instead bainite. Interphase boundary precipitation of vanadium has related to
boundary migration during ferrite transformation from austenite in isothermal phase
transformation. Studies on heat-treatment of service exposed rotor steel has showed
removal of grain boundary precipitates and regaining life by formation of equi-disperse
precipitation over matrix at the expense of grain boundary precipitates. Long term boiler
tube applications has stated to be formation of coherent precipitation, which in subsequent
period has formed stable Laves phases to control over microstructural stability. Hydrogen
embrittlement has reduced by trapping source in steel. Vanadium precipitates has been
effective source for trapping. V precipitates act as one type of trap with specific activation
energy. Phosphorous segregation has always appeared too dominated through grain
boundaries than bulk diffusion.