ZHAO Dewen
,
XIE Yingjie
,
LIU Xianghua
,
WANG Guodong
钢铁研究学报(英文版)
Using the twin shear stress yield criterion, the surface integral of the coline vectors, and the integration depending on upper limit, Kobayashi′s threedimensional velocity field of rolling was analyzed and an analytical expression of rolling torque and single force was obtained. Through redoing the same experiment of rolling pure lead as Sims, the calculated results by the above expression were compared with those of Kobayashi and Sims formulae. The results show that the twin shear stress yield criterion is available for rolling analysis and the calculated results by the new formula are a little higher than those by Kobayashi and Sims ones if the reduction ratio is less than 30%.
关键词:
twin shear stress yield criterion;coline vector integral;threedimensional rolling;analytical solution
LAN Liangyun
,
QIU Chunlin
,
ZHAO Dewen
,
GAO Xiuhua
,
DU Linxiu
钢铁研究学报(英文版)
The recrystallization behavior of a low carbon high Nb microalloyed steel was investigated using Continuous and interrupted hot compression tests. The results showed that the onset of dynamic recrystallization (DRX) could be detected from inflection in the plot of the strain hardening rate θ against stress σ regardless of whether the stress peak appears or not. According to Zener-Hollomon parameter the activity energy of DRX (Qdef) was obtained, and a new modified expression calculating Qdef was proposed in consideration of the chemical composition of experimental steel. Applying the 2% offset method the static softening fraction was determined. The graphic representation of the softening fraction vs. interrupt time gave the information of the non-static recrystallization temperature (about 1000℃)and the relationship of precipitation-time-temperature. Static recrystallization kinetics follow Avrami’s law in high deformation temperature, and different values of the exponent n were given to illustrate the different effects of Nb element on static recrystallization at different deformation temperature.
关键词:
dynamic recrystallization;static recrystallization;high Nb microalloyed steel;activity energy.
