摘要
利用热力模拟、EBSD和TEM等方法,研究了Incoloy 028合金在1000~1150℃和0.001~1 s-1应变速率条件下的不连续动态再结晶(DDRX)行为,分析了DDRX过程中链状组织的形成机理。结果表明,随着变形温度降低或应变速率升高,体系发生传统型向链状型DDRX转变,其中传统型DDRX过程由晶粒长大主导,主要在三叉晶界处形核;链状型DDRX发生多层形核长大,其第一层形核机制为孪晶界辅助的原始晶界弓出形核,后续层为亚晶扭转与三叉晶界形核;孪晶界在辅助形核后消失以提高界面移动性,晶粒长大时再次形成以降低体系能量。
During hot deformation, discontinuous dynamic recrystallization（DDRX） taking place by nucleation and growth in materials with low to medium stacking fault energies（SFEs）, plays a crucial role in grain refinement, especially for the material with coarse grains. In order to study the formation mechanism of typical microstructure（necklace structure） during DDRX, the behavior of Incoloy 028 alloy at temperature range of 1000-1150 ℃ and the strain rates of 0.001-1 s^-1 was investigated by means of thermodynamic simulation, EBSD and TEM. The results show that with the decrease of deformation temperature or the increase of strain rate, the mechanism of DDRX is transformed from the traditional type nucleating at triple junctions, into necklace structure which dominated by the multilayer nucleation mechanism.The first strand of recrystallized grain is nucleated through the bulging of serrated grain boundaries which is assisted by twinning at the back of the fluctuation. With the increase of the true strain, the large strain gradient in the deformation band develops rapidly resulting in the transformation of the subgrain boundary into a high angle grain boundary, and then the second/followed layer nucleation occurs by the rotation of subboundaries accompanied with nucleation at triple junction. Twin boundaries are formed by straininduced grain boundaries migration and disappeared after nucleation to enhance the recrystallization grain boundary mobility, and then formed again during growth to lower the interfacial energy of the system.
作者
钟茜婷
王磊
刘峰
ZHONG Xiting;WANG Lei;LIU Feng(State Key Lab of Solidification Processing,Northwestern Polytechnical University,Xi＇an 710072,China;Tubular Goods Research Institute ofCNPC,Xi＇an 710077,China)
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2018年第7期969-980,共12页
Acta Metallurgica Sinica
基金
国家自然科学基金项目No.51431008
国家重点研发计划项目Nos.2017YFB0703001和2017YFB0305100
凝固技术国家重点实验室研究基金项目No.117-TZ-2015~~
关键词
热变形
不连续动态再结晶
链状组织
孪晶界
亚晶界
hot deformation
discontinuous dynamic recrystallization
necklace structure
twin boundary
subgrain boundary
