Dissolution and Precipitation behaviors of Complex Carbonitrides in Austenite of a V-Nb Microalloyed Steel

Abstract

Dissolution and precipitation behaviors of complex carbonitrides in austenite of a V-Nb microalloyed steel were quantitatively examined through electrical resistivity measurement and transmission electron microscopy. The electrical resistivity increased with solution treatment temperature up to 1240℃ and then was saturated at 225 nΩm for a holding time of 10 min. The electrical resistivity method was also used to quantitatively measure the isothermal precipitation kinetics of the complex carbonitrides in austenite. Nb- rich precipitates were observed in austenite at the early stages of precipitation, but Nb was replaced by V up to the equilibrium amount within the precipitates with further holding time. The time-temperature- precipitation diagram showed a C-type curve; nose temperature and its incubation time were 900℃ and 100 s, respectively. (Received June 29, 2011)