超薄Inconel 718镍基合金板焊接凝固过程中微观组织变化的预测

Prediction of Change in Microstructure of Ultra-thin Inconel 718 Alloy Sheet during Welding Solidification

以不同的占空比、基值电流、峰值电流和脉冲频率对0.1 mm厚Inconel 718合金板进行了脉冲微束等离子弧焊(pulse microplasma arc welding,P-MPAW)。对焊接凝固过程中超薄版的微观组织的变化进行了数值模拟。采用Fluent软件对焊接过程中超薄板的温度场变化进行了模拟,并与采用MATLAB软件建立的微观组织变化模型进行耦合,以预测超薄Inconel 718合金板在脉冲微束等离子弧焊接凝固过程的微观组织变化。结果表明:占空比对焊缝边缘柱状晶二次枝晶和焊缝中心等轴晶一次枝晶的生长均有明显影响;脉冲频率和基值电流均影响柱状晶和等轴晶晶粒的平均尺寸;模拟的和试验获得的柱状晶和等轴晶晶粒平均尺寸相接近,说明采用该模型分析P-MPAW焊接超薄Inconel 718合金板时在凝固过程中微观组织的变化是可行的。

0.1-mm-thick Inconel 718 alloy sheet was pulse microplasma arc welded at different duty ratios,base and peak currents,and pulse frequencies.The change in microstructure of the ultra-thick sheet during solidification of welding was numerically simulated.The change in temperature field in the ultra-thick sheet during welding was simulated by a Fluent software,and coupled with a microstructure variation model which was established by MATLAB software,to predict the change in microstructure of the ultra-thick Inconel 718 alloy sheet during solidification of P-MPAW.The results indicated that(a)the duty ratio had significant effect on growth of the secondary dendrite of columnar crystal in weld side and the primary dendrite of equiaxed crystal in weld centre;(b)the pulse frequent and the base current all exerted an evident influence on average size of grains of columnar crystal and equiaxed crystal;and(c)the simulated average sizes of grains of columnar crystal and equiaxed crystal approached to those derived from test,indicating the use of this model to analyze the change in microstructure of ultra-thick Inconel 718 alloy sheet during solidification of P-MPAW was feasible.