Research Of Primary And Secondary Recrystallization Of Hi-B Steel Produced By Stimulating CSP Process

The research of Hi-B steel produced by CSP technology has attracted greatattention, because of the problems of traditional process such as the high cost and highenergy consumption. CSP technology was simulated to product Hi-B steel in laboratory,and a range of experiments from steelmaking to secondary recrystallization annealingwere designed. Evolution of microstructure and texture in the primary and secondaryrecrystallization annealing process of Hi-B steel were studied by EBSD and XRDtechnique, also effects of different process on secondary recrystallization were discussed.The main results are as follows:(1)The primary recrystallization of Hi-B steel finished in15s at830℃. With theincreasing of annealing time, the grain size gradually grew up, the proportion of Σ1interface decreased, but the proportion of Σ3~Σ9interface proportion did not changemuch, while misorientation distributions changed into a majority of high angle grainboundaries.(2)Abnormal growth of goss grains occurred in1100℃with the heating rate of20℃/h during the process of high-temperature annealing, the behavior of its growth wasdifferent from normal grain growth. After abnormal growth, goss grains had sizeadvantage, goss texture dominated the texture component gradually. Secongdaryrecrystallization of Hi-B steel was divided into three stages, namely early stage ofslowing growth, intermediate stage of preferred growth and the final stage ofswallowing island grains. At different stage, the mechanism of growth of goss grainswas different.(3)Cold rolling reduction, normalizing and heating rate affect the evolution of gosstexture. The reduction, either too large or too small, was not conducive to the abnormalgrowth of goss grains. A lot of AlN particles, which almost didn’t precipitate during hotrolling, precipitated during normalizing. This change had no obvious effect onmicrostucture and texture of primary recrystallization, however, it greatly improved the grain size of secondary recrystallization. The inappropriate heating rate can lead toinhomogeneous microstructure and weak goss texture.