电子束选区熔化增材制造Ti-55531合金的凝固及相变行为研究  

Research on Solidification and Phase Transition Behavior of Ti-55531 Alloy Made of Electron Beam Selective Melting Additive

作　　者：张林嘉 张安琴 常玥莹 高军 邓浩 ZHANG Linjia;ZHANG Anqin;CHANG Yueying;GAO Jun;DENG Hao

机构地区：[1]海装广州局驻贵阳地区军事代表室,贵阳550000 [2]中国航发贵阳发动机设计研究所,贵阳550000 [3]中国第二重型机械集团德阳万航模锻有限责任公司,四川德阳618000

出　　处：《大型铸锻件》2024年第4期28-32,共5页Heavy Casting and Forging

摘　　要：通过电子束选区熔化(EBM)技术制造了Ti-5Al-5Mo-5V-3Cr-1Zr(Ti-55531)合金,研究了打印过程中的凝固及相变行为。首先样品沿构筑方向形成了粗大的柱状晶,这是因为EBM过程中熔池凝固前沿较低的形核能垒,将导致晶粒的临界形核半径r*趋于0,无法生成等轴晶粒。同时凝固方式由平面凝固转为枝晶凝固,较低的等轴枝晶比例使得无法发生柱状晶向等轴晶的转变,在重熔区和定向热流的影响下,晶粒沿构筑方向发生跨层生长成柱状晶。并且沿构筑方向样品的微观组织呈现梯度结构,随着沉积高度的增加,片层初生αp的比例降低,宽度增加,而次生αs的比例升高,这是沿构筑方向的热量累积和基板加热的原位热处理共同作用的结果。The solidification and phase transition behavior during printing process of Ti-5Al-5Mo-5V-3Cr-1Zr(Ti-55531)alloy made by selective electron beam melting(EBM)technology was investigated.Firstly,coarse columnar grains formed in the direction of construction of sample,the low nucleation barrier at the solidification front of the melt pool during EBM leads the critical nucleation radius of the grain r*to tend to 0,the equiaxed grains cannot be generated.At the same time,the solidification mode changes from planar solidification to dendrite solidification,and the low equiaxed dendrite ratio makes it impossible to transform from columnar to equiaxed grain.Under the influence of the remelting zone and directional heat flow,the grains grow into cross-layered columnar crystals along the construction direction,and the microstructure of the samples shows a gradient structure along the construction direction.With the increase of deposition height,the proportion of primaryαp in the sheet decreases,the width increases,and the proportion of secondaryαs increases,which is the result of the combined effect of heat accumulation along the construction direction and in-situ heat treatment of substrate heating.

关 键 词：电子束选区熔化 Ti55531合金 凝固行为 相变 

分 类 号：TG44[金属学及工艺—焊接]