Papers by Author: Qi Fang

Abstract: Rare earth (RE) has purification, denatured mixture and micro alloy function in steel. High Nb containing in steel can expend austenite non-recrystallization region, improve rolling temperature and lower equipment load. Effect of RE on dynamic recrystallization of low carbon high niobium steel is investigated by using thermal simulation experiment in this paper. Experimental results show that dynamic recrystallization does not occur in two test steel below 1000°C. RE elements can increase dynamic recovery beginning strains, refine and disperse M/A organization and change precipitates into small triangle shape.

Abstract: The solid solution of the second phase particle and austenite grain growth behavior of the high niobium-containing RE steel was studied by mathematical calculation and extraction replica technique. The purpose of the study was to investigate the effects of Rare Earth La on austenite grain growth and propose an empirical equation for predicting the austenite grain size of RE steel. Austenite grain grows in an exponential law with the increase of heating temperature, while approximately in a parabolic law with the increase of holding time. Results show that the RE steel has good anti-coarsening ability at elevated temperatures. When soaking temperature is lower than 1250°C , AGS and growth rate are small for high niobium steel, but soaking temperature is lower than 1220°C , AGS and growth rate are small for RE steel. RE La can promote solid solution of second-phase particles Nb(C, N), the solution temperature decrease 30°C than high niobium steel.