Influence of Annealing Parameters on the Microstructural Characterization in a Nb-microalloyed Quenching and Partitioning Steel with Partial Austenization
Quenching and partitioning treatment (Q&P) applied to the Nb microalloying cold-rolled high strength medium manganese steel under partial austenitizing status is both theoretically and experimentally studied,by means of Thermo-Calc software,Scanning electron microscopy (SEM),and X-ray diffraction (XRD).The steel with different ferrite volume is partially austenitized at different intercritical temperature.An empirical relation combinating with the intercritical austenitic composition from the appropriate database TCFE7 contributes to the Ms Temperature of these specimens.Then the theoretically optimal quenching temperature is achieved by CCE.Theoretical calculations predict the available final retained austenite fraction and the average carbon content of the steel with different ferrite volume at the optimal quenching temperature.The average carbon content of retained austenite gradually decreases with the increasing quenching temperature in the samples under different austenitizing temperature.Besides,the optimal quenching temperature shifts to the lower temperature with the decreasing of partial austenitizing temperature owing to the enrichment of both carbon and manganese in intercritical austenite.The final retained austenite volume obtained by XRD measurement is smaller than the result of the theoretical calculation.This phenomenon is attributed to the limitations of CCE balance equation and the deviation of the intercritical austenite composition and fraction.There are the inevitable carbides precipitations with the addition of Nb in the steel.
quenching and partitioning retained austenite microstructure
ZHAO Zhengzhi LIANG Juhua LIANG Jiangtao TANG Di
Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing,Beijing 100083, China
国际会议
成都
英文
375-378
2016-11-16（万方平台首次上网日期，不代表论文的发表时间）