电子束选区熔化成形角度对TC4合金组织的影响

Effect of Forming Direction on Microstructure of TC4 Titanium Alloy Prepared by Electron Beam Selective Melting

利用电子束选区熔化技术制备90°、60°、30°和0°的7 mm TC4钛合金试样板,研究了成形角度对显微组织的影响。结果表明:电子束选区熔化制备的试样具有平行于扫描方向的层带组织;90°、60°和30°试样中的β柱状晶贯穿多个层带,其主轴平行于粉末沉积方向,β柱状晶内针状马氏体α'相互交错形成网篮状魏氏组织,β柱状晶和马氏体α'的宽度随成形角度减小而增大;成形角度为0°的试样组织为细长的β晶粒,β晶内α相平行分布形成α集束,各β晶粒中的α集束取向不同。

TC4 titanium alloy plates with the thickness of 7 mm at the angles of 90°, 60°, 30° and 0° were formed by electron beam selective melting. The effects of forming directions on the microstructure were investigated. The results show that there are layer bands which are parallel to the scanning direction in samples prepared by electron beam selective melting. β columnar crystals cross through many layer bands in the samples at the angles of 90°, 60°, 30°, and the main axes are parallel to the direction of powder deposition. Acicular martensite α＇ in β columnar crystals crosses with each other, which can form basketweave widmanstatten structure. The widths of β columnar crystals and acicular martensite α＇ increase with the decrease of build angle. There are long and thin β grains in the samples at the angle of 0°. And the α colony is formed with α phase distributing in parallel in β grains. The orientation of α colony is different in each β grain.