电弧增材制造TC4钛合金宏观晶粒演化规律

Macrostructure Evolution of TC4 Titanium Alloy Fabricated by Wire and Arc Additive Manufacturing

由于电弧增材制造是目前众多增材制造方法中的研究热点之一,且TC4是研究最广泛的钛合金,因此本工作研究了电弧增材制造TC4直壁墙的宏观组织演变。首先通过单道单层实验修正双椭球热源模型的形状参数,应用修正后的模型模拟四组直壁墙成形过程中的温度场及温度变化速率,通过模拟结果分析组织的演变规律。直壁墙底部为等轴晶组织,上部为柱状晶组织。低焊接电流有助于等轴晶的形成,但等轴晶区的尺寸及等轴晶的大小与线能量密度无关。

As wire and arc additive manufacturing has been a hot area research among the many additive manufacturing methods,and TC4 is the most widely researched titanium alloy.Therefore the macrostructure evolution of the TC4 straight walls manufactured by WAAM was researched in this study.Firstly,the shape parameters of the double ellipsoidal heat source model were validated by single-track and single-layer experiments.The thermal field and thermal changing rate during the deposition process of the four straight walls were simulated using the modified model,and the evolution processes were analyzed by simulation results.The bottom of the straight wall are equiaxed grains and the upper part are columnar grains.The low welding current contributes to the formation of equiaxed grains,but the height of the equiaxed grain zone and the size of the equiaxed grains are independent of the line energy density.