利用选区激光熔化技术制备梯度结构的Ti-6Al-4V合金

Additive Manufactured Ti-6Al-4V Alloy with Graded Micro-structure by Selective Laser Melting

摘要:

采用选区激光熔化技术（SLM）制备了梯度Ti-6Al-4V合金。随着样品沉积厚度的逐渐增加，控制激光功率或扫描速率逐步升高或降低，以此研究了梯度结构Ti-6Al-4V合金的相变及结构演变。结果表明：由于选取激光熔化过程中的高冷却速率，SLM制备的Ti-6Al-4V合金的主要组织结构为初始β柱状晶里的针状马氏体。β柱状晶会随着激光功率的增加或扫描速率的降低而增宽。激光功率和扫描速率的变化会引起马氏体择优取向的变动。最后，由于局部不同的能量变化，随样品沉积厚度增加而逐步升高或降低的扫描速率会引发2种不同的空洞缺陷。

Abstract:

Graded Ti-6Al-4V alloys were produced by selective laser melting (SLM). Regulation of laser power and scanning speed was applied separately on each sample along the building direction. The microstructure transformation and phase transition in the graded Ti-6Al-4V were investigated. Results show that due to the rapid cooling rate of the SLM process, the microstructure of Ti-6Al-4V is mainly acicular α′ martensite in prior β column grains. The β column grains are enlarged with the increase of laser power or the decrease of scanning speed. The preferential orientation of α′ grains changes due to the variation of laser power and scanning speed. Moreover, the ascending scanning speed or descending scanning speed during the process may lead to two different defects.