热输入对脉冲等离子弧增材制造Inconel 718合金组织与性能的影响

Influence of Heat Input on Microstructure and Mechanical Property of Pulsed Plasma Arc Additive Manufactured Inconel 718 Superalloy

采用基于脉冲等离子弧的增材制造技术在Q235基板上加工了Inconel 718合金试样,通过改变功率和焊接速度研究了不同热输入对试样组织与性能演变规律的影响。借助光学显微镜、扫描电镜、能谱分析、维氏硬度仪等手段对试样晶粒形态、枝晶间距、元素偏析、析出相成分及分布、显微硬度等进行表征,结果表明随着热输入从1.08×106 J/m增大至1.76×106 J/m,晶粒形态从细长的柱状枝晶逐渐转变为粗大的胞状枝晶,枝晶间距从6.34μm增大至9.09μm,Nb、Mo等元素在枝晶间偏析加剧,Laves相由颗粒状、块状逐渐变为长链状,显微硬度不断下降。

The effect of heat input on microstructure and mechanical property of pulsed plasma arc additive manufactured Inconel 718 superalloy samples were investigated.Five different heat inputs ranging from 1.08×10^6 J/m to 1.76×10^6 J/m were adopted by changing power and welding speed.The microstructure morphology,dendritic spacing,elemental segregation and interdendritic Laves phase were also studied by using optical microscopy（OM）,scanning electron microscopy（SEM）and energy dispersive spectroscopy（EDS）.The results show that as the heat inputs increase,the microstructure morphology is changed from columnar dendrites to cellular dendrites,and dendritic spacing also increases from 6.34μm to 9.09μm.Consequently,elemental segregation of Nb and Mo are promoted so that the morphology of interdendritic Laves phase is changed from particles to chains,which leads to the decrease of microhardness.