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TC4钛合金激光再制造非均质组织微区变形行为

Microzone deformation behavior of inhomogeneous microstructure in laser-remanufactured TC4 titanium alloy

  • 摘要: 激光再制造技术不可避免会在修复界面位置产生非均匀组织,严重影响再制造构件的使役性能.文中重点分析TC4钛合金激光再制造非均质组织在载荷作用下的介观变形行为,基于真实微观组织建立晶体塑性有限元模型,选取非均质组织不同微区进行仿真,分析不同微区在载荷作用下的应力云图. 结果表明,根据激光热源的作用情况,可以将TC4钛合金激光再制造非均质组织分为5个不同区域:修复区、HAZβ区、粗晶HAZα + β区、细晶HAZα + β区和母材区. 不同区域的应力分布与微观组织形态密切相关,修复区表现为晶内滑移引发的位错积累以及相界面处的应变失配两种模式;HAZβ区应力集中分布于晶粒取向差大、尺寸差异显著的交界区域;HAZα + β区可以通过块状α相协调晶内/晶间变形有效分散应力,有着较高的抗应力集中能力.

     

    Abstract: Laser remanufacturing technology inevitably generates an inhomogeneous microstructure at the repair interface, which severely affects the service performance of remanufactured components. This paper focused on the mesoscopic deformation behavior of the inhomogeneous microstructure in laser-remanufactured TC4 titanium alloy under loads. A crystal plasticity finite element model was established based on the authentic microstructure. Different microzones of the inhomogeneous microstructure were selected for simulation analysis, and the stress contour maps of different microzones under loads were analyzed. The results indicate that according to the action of the laser heat source, the inhomogeneous microstructure in laser-remanufactured TC4 titanium alloy is divided into five different zones: remanufactured zone, HAZβ zone, coarse-grained HAZα + β zone, fine-grained HAZα + β zone, and base metal zone. The stress distribution in different zones is closely related to the microstructural morphology. The remanufactured zone exhibits two modes: dislocation accumulation caused by intragranular slip and strain mismatch at the phase interface. In the HAZβ zone, the stress is concentrated in the boundary regions with large grain orientation differences and significant size differences. The HAZα + β zone effectively disperses stress by coordinating intragranular and intergranular deformation through massive α phases, showing a high resistance to stress concentration.

     

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