摘要
钛及钛合金变形机制主要有滑移和孪生。形变孪晶的生成分为形核和长大两个阶段。形变孪晶在钛合金变形中的作用:(1)多种塑性变形过程,当位错滑移困难时,形变孪晶起到协调变形的作用,例如,纯钛中的■等形变孪晶可协调c轴塑性变形,在高速压缩和等通道转角挤压等特殊工艺条件下孪晶仍起到协调变形的作用;(2)在压缩、等通道转角挤压和轧制等工艺条件下,形变孪晶引起大量晶粒发生转动,促进新织构的生成;(3)形变孪晶激活后钛合金产生明显的应变硬化效应,这是由于多孪晶的交叉作用;(4)形变孪晶还能产生孪晶诱发塑性效应。形变孪晶对钛合金再结晶也有促进作用,这是由于孪晶界是局部高能区,可提供合适的再结晶形核位置。室温激活孪晶诱发静态再结晶细化晶粒;热加工过程激活的孪晶同时诱发动态再结晶过程;液氮温度激活孪晶诱发之后的动态再结晶细晶效果明显,通过液氮温度多向压缩激活高密度均匀孪晶,再进行热压缩诱发动态再结晶,可获得细小均匀的等轴晶组织。
The deformation mechanisms of titanium and titanium alloys were slip and twinning.The activation of deformation twins included two stages,i.e.nucleation stage and growth stage.The role of deformation twins of titanium alloys during deformation processes were:(1)they could coordinate deformation when dislocations were hard to slip during multi plastic deformation processes.For example,deformation twins like■twins could coordinate plastic deformation in c axis.They could even coordinate deformation during high-speed compression or equal channel angular pressing processes;(2)they could induce grain rotation to facilitate the formation of new texture during compression,equal channel angular pressing or rolling processes;(3)they had strain-hardening effect due to interaction of multiple twins;(4)they had twinning induced plasticity effect.Deformation twins of titanium alloys could promote recrystallization,which was due to that twin boundaries could provide appropriate recrystallization sites as locally high-energy zone.Twins activated at ambient temperature could induce static recrystallization.Twins activated during hot deformation could induce dynamic recrystallization.The dynamic recrystallization and grain refinement effect was more obvious after the activation of twins at cryogenic temperature.Homogeneous and refined grains could be achieved by the activation of high-density twins via multi-directional compression at cryogenic temperature and hot compression to activate dynamic recrystallization.
作者
闫辰侃
曲寿江
冯艾寒
沈军
Yan Chenkan;Qu Shoujiang;Feng Aihan;Shen Jun(School of Materials Science and Technology,Tongji University,Shanghai 201804,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2019年第5期449-460,共12页
Chinese Journal of Rare Metals
基金
国家自然科学基金青年科学基金项目(51305304)
国家自然科学基金联合重点基金项目(U1302275)
国家科技部国家科技重大专项课题项目(2013ZX04011061)资助
关键词
钛
形变孪晶
织构演化
再结晶
titanium
deformation twins
texture evolution
recrystallization
