论文部分内容阅读
针对7050铝合金表面激光熔覆Al/Ti复合粉体,建立了三维瞬态温度场有限元模型,模拟了不同离焦量条件下的熔池大小、温度梯度、冷却速度及形状控制因子。结果表明,熔池宽度与深度尺寸随着离焦量数值的增大先增大后减小,在离焦量为20 mm时熔池宽度与深度都出现了最大值。沿熔池深度方向(即Z向)的温度梯度数值最大,散热条件最好,表明熔覆凝固过程中的晶粒生长方向主要集中在Z向。离焦量为40 mm时的冷却速度最大、晶粒细小,离焦量为80 mm时的冷却速度最小、晶粒粗大,且得到实验验证。离焦量为60 mm时的形状控制因子最大,金相组织出现柱状晶;离焦量为80 mm时的形状控制因子最小,金相组织主要为胞状晶,并有相应的实验验证。
Aiming at the laser cladding Al / Ti composite powders on 7050 aluminum alloy surface, a three-dimensional transient temperature field finite element model was established to simulate the bath size, temperature gradient, cooling rate and shape control factor under different defocus conditions. The results show that the width and depth of the weld pool first increase and then decrease with the increase of the defocus amount, and the maximum of the weld pool width and depth appears when the defocus amount is 20 mm. The temperature gradient along the depth of the weld pool (ie, the Z direction) is the largest, with the best cooling conditions, indicating that the direction of grain growth during the solidification is mainly in the Z direction. When the defocus amount is 40 mm, the cooling rate is the largest, the grains are fine, the cooling rate is the smallest when the defocus amount is 80 mm, the grains are coarse, and the experiment is verified. When the defocus amount is 60 mm, the shape control factor is the largest, and the columnar crystal appears in the microstructure. When the defocus amount is 80 mm, the shape control factor is the smallest, and the microstructure is mainly the cellular crystal with the corresponding experimental verification.