Fabrication of high-quality Ti joint with ultrafine grains using submerged friction stirring technology and its microstructural evolution mechanism
Fabrication of high-quality Ti joint with ultrafine grains using submerged friction stirring technology and its microstructural evolution mechanism
复制标题
浸没搅拌摩擦技术制备高质量超细晶钛接头及其组织演化机制
DOI：
10.1016/j.actamat.2018.12.059
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发表时间：
2019
期刊：
影响因子：
9.4
通讯作者：
Xiao B. L.
中科院分区：
文献类型：
--
作者：
Wu L. H.;Hu X. B.;Zhang X. X.;Li Y. Z.;Ma Z. Y.;Ma X. L.;Xiao B. L.
传统搅拌摩擦焊由于存在过热问题，很难获得高质量的钛接头。焊接过程以及接头的最终显微组织和性能由塑性变形和再结晶控制。然而长期以来，研究仅关注再结晶机制而忽视了变形模式。在这项研究中，首次采用浸没搅拌摩擦（SFS）技术生产出接头效率为100%的无缺陷超细晶钛接头。我们利用透射电子显微镜与两束衍射技术和电子背散射衍射系统地研究变形模式与晶粒细化机制。利用有限元方法模拟整个接头的温度场以解释微观结构。在整个SFS过程中，发生了棱柱滑移，其他主要变形机制从{10 1´ 2}孪生和基底滑移转变为金字塔< a+ c>滑移。滑移模的变化很大程度上取决于孪生和温升。超细晶微观结构归因于孪生位错相互作用、位错吸收、动态晶界迁移和织构诱导晶粒收敛的连续细化效应。讨论了温度、应变和应变速率对微观结构演化机制的影响。根据我们的工作，我们期望SFS在生产超细晶块体钛材料和高质量接头方面得到广泛应用。
It is rather challenging to obtain high-quality Ti joints by conventional friction stir welding because of the problem of over-heating. The welding process and final microstructures and properties of the joints are controlled by both plastic deformation and recrystallization. However, for a long time, studies have only focused on recrystallization mechanisms but ignored deformation modes. In this study, a defect-free ultrafine-grained Ti joint with a joint efficiency of 100% was for the first time produced by submerged friction stirring (SFS) technology. We utilized transmission electron microscopy with a two-beam diffraction technique and electron backscatter diffraction to systematically investigate the deformation mode versus the grain refinement mechanism. The finite element method was utilized to simulate the temperature field throughout the joint for the microstructural explanation. During the whole SFS, prismatic slip occurred, and the other dominant deformation mechanisms changed from {10 1¯ 2} twinning and basal slip to pyramidal< a+ c> slip. The variation of slip modes was largely dependent on the twinning and temperature rise. The ultrafine-grained microstructure was attributed to the successive refinement effect of the twin-dislocation interaction, dislocation absorption, dynamic grain boundary migration and texture-induced grain convergence. The effect of the temperature, strain and strain rate on the microstructural evolution mechanisms was discussed. Based on our work, we expect the wide application of SFS in producing ultrafine-grained bulk Ti materials and high-quality joints.