热变形对TA19闪光焊接组织均匀化的影响

Effect of hot deformation on microstructure homogenization of flash welded TA19 alloy

摘要:

为消除TA19闪光焊接接头的组织不均匀性，改善闪光焊接TA19的综合性能。利用Gleeble3500热模拟试验机对TA19闪光焊接头在变形温度900~980℃，变形量30%、60%，变形速率0.01~1s-1条件下进行等温恒定速率热压缩试验，以研究其组织在不同变形参数下的转变特征。实验结果表明，焊接接头试样在压缩过程中流变应力-应变曲线呈现动态软化趋势，在低变形速率条件下片状α相动态回复、动态再结晶过程充分发生，促进其宽度尺寸的增加，β相楔入导致片状α相断开。随变形量与变形温度的增加，在动态再结晶以及元素扩散作用下，片层α相等轴化比例逐渐提高。变形过程中有残留β相被破碎，部分转变为富Mo的颗粒分布在α相基体上。在随后的热处理过程，α基体上富Mo颗粒回溶到β相，β相长大完成对片层α相的分割，α相进一步通过静态再结晶完成等轴化。闪光焊接试样在980℃、变形速率0.01s-1、60%变形量下变形后，经930℃1h+590℃4h空冷的退火处理，可充分实现焊缝组织的等轴化转变，热处理后焊接接头组织以等轴组织为主，组织均匀性明显改善。

Abstract:

In order to eliminate the microstructure inhomogeneity of TA19 flash welding joint and improve the comprehensive properties of TA19 flash welding joint. Use Gleeble3500 thermal simulation testing machine on TA19 flash welding head in deformation temperature 900~ 980 ℃, the deformation were 30%, 60%, deformation rate of 0.01 ~ 1 s- 1 for isothermal constant rate under the condition of hot compression test, as to research in welding joint organization under different deformation parameters change characteristics. The experimental results showed that the rheological stress curve of the welded specimen showed a dynamic softening trend during the compression process, and the recovery and recrystallization of the flaked phase were sufficient under the condition of low deformation rate, which promoted the increase of its width and size, and the wedge of phase resulted in the disconnection of the flaked phase. With the increase of deformation amount and deformation temperature, under the action of dynamic recrystallization and element diffusion, the equiaxial ratio of sheet increases gradually. In the process of deformation, residual phases were broken and some mo-rich particles were distributed on the phase matrix. In the subsequent heat treatment process, Mo rich particles on the matrix were dissolved back into phase, which was grown to complete the segmentation of the phase, which was further axialized by static recrystallization. Flash welding specimens under 980 ℃, deformation rate 0.01 s- 1, after 60% deformation under deformation, by 930 ℃ for 1 h + 590 ℃ for 4 h air cooling annealing treatment, can fully realize the weld microstructure of transition such as axis, heat treatment after welding joint organization is given priority to with shaft such as organization, organization uniformity obviously improved.