Song Hongwu

FLOW SOFTENING MECHANSIM OF A Ti ALLOY WITH LAMELLAR STRUCTURE DURING SUBTRANSUS DEFORMATION

The flow stress has a considerable flow softening after a peak strain hardening at very low strains for Ti alloys with lamellar structure during subtransus deformation.In order to study the mechanism of such flow softening behavior,the deformation behavior of TC11 Ti alloy with a lamellar structure was studied using isothermal hot compression tests under a temperature range of 890—995℃and a strain rate range of 0.01-10 s~(-1).Theoretical calculation shows the Hall-Petch strengthening effects induced byα/βinterface as well as the twin boundary inαlamellar are far more significant than that of the colony boundary.The flow softening can be related to reduction of Hall-Petch strengthening effects due to transfer from the hard slip mode to the soft one.

THE TEXTURE EVOLUTION AT THE CENTER OF PEARLITIC STEEL WIRE DURING DRAWING AND ITS INFLUENCE ON THE MECHANICAL PROPERTIES

The cold drawing pearlitic steel wires are widely used in industry such as the automobile tire and ropes. And it possesses an ultra high strength, almost the highest in all the steel products. So many investigations are focused on the hardening mechanisms of pearlitic steel wire during cold drawing, including the microstructure fining, texture evolution and cementite dissolution. In this study, the electron backscatter diffraction (EBSD) and the visco-plastic selfconsistent (VPSC) model are used to investigate the texture evolution law at the center of wire during the drawing, as well as its influences on the mechanical behaviors. The EBSD results show that the asreceived wires after dry drawing and quenching have a little fiber texture along the drawing direction. And with wet drawing strain increasing, the intense of fiber texture increases apparently. The calculations using *贝卡尔特(亚洲)研发中心合作项目,国家自然科学基金项目51034009和广东省中国科学院全面战略合作项目2012B091100251资助 收到初稿日期: 2013-12-09,收到修改稿日期: 2014-02-27 作者简介:赵天章,男, 1987年生,博士生 DOI: 10.3724/SP.J.1037.2013.00799 第667-673页 pp.667-673