工艺参数设置和厚度对电子束熔融加工Ti-6Al-4V合金微观结构的影响

研究了试件尺寸和工艺参数(电子束强度,扫描速度,焦点偏移量和扫描长度)对电子束熔融(EBM)加工Ti-6Al-4V合金微观结构的影响。结果表明,可以观察到EBM加工的Ti-6Al-4V合金的微观结构由原始β相的柱状晶粒组成。在柱状晶粒内部观察到典型的(α+β)结构,即魏氏体α片和在细小的α晶粒的界面上形成的杆状β相。还发现沿原始β柱状晶粒的晶界形成的α层晶界。随着试件厚度、电子束能量密度和扫描长度的增加,先前的β柱状晶粒的直径增大,并且生长的方向与加工方向一致。同时,柱状晶粒直径随着试件高度的增加而减小。随着试件厚度和电子束能量密度的增加,α片会变得更粗大。

Effect of Process Parameters Settings and Thickness on Microstructures of EBM Produced Ti-6Al-4V

The effect of sample dimensions and process parameters(beam current, scan speed, offset focus and scan length) of electron beam melting(EBM) system on microstructure of the EBM built Ti-6 Al-4 V alloy was investigated. The microstructure of EBM built Ti-6 Al-4 V alloy consists of columnar grains of prior β phase. Inside the columnar grain, typical(α+β) structures, namely Widmanst?tten α platelets and rod-like β phase formed on the interfaces of the fine α grains, are observed. Grain boundary α layer forms along grain boundary of prior β columnar grain. With the increase of thickness of the test slab, beam energy density and scanning length, the prior β columnar grain grows along the build direction and diameter of which increases. The columnar grain diameter also decreases with the increase in height of the test slab. With increasing the thickness of the test slab and beam energy density, α platelets get coarser.