Multi-laser powder bed fusion of Ti6Al4V: Diode area melting utilizing low-power 450 nm diode lasers
Multi-laser powder bed fusion of Ti6Al4V: Diode area melting utilizing low-power 450 nm diode lasers
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DOI：
10.1016/j.jmatprotec.2024.118303
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发表时间：
2024-02-03
影响因子：
6.3
通讯作者：
Mumtaz，Kamran
中科院分区：
文献类型：
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作者：
Caglar，Halil;Liang，Anqi;Mumtaz，Kamran
二极管区域熔化（DAM）是激光粉末床熔化的一种创新方法。本研究首次利用多个低波长（450nm）和低功率激光器（每个4w）同时从粉末床中加工Ti6Al4V，得到高密度样品（> 99%）。与传统的单激光LPBF系统相比，使用垂直于扫描方向的9个激光器可以创建宽度大于1000 μ m的熔池，减少了一层内的通过次数。然而，熔池宽度的增加带来了与保持均匀熔池渗透深度相关的挑战，这一实习生带来了在多层零件中实现高密度的问题。建立了基于归一化能量密度的参数映射。该研究还考察了不同工艺条件（扫描速度、舱口距离和层高）、归一化能量密度对致密化、微观结构和硬度的影响。在每层上实施重新扫描策略可以降低平均表面粗糙度并增加密度，同时降低硬度约40%。x射线衍射分析表明，随着能量密度的增加，β相出现。由于冷却速度较慢，在下部观察到较粗的片层组织，而在上部观察到较细的马氏体组织，导致整个样品呈篮织型组织。此外，在没有蚀刻的情况下，可以看到片层状亚晶粒。这项创新技术表明，一组低功率激光器可以熔化和融合Ti6Al4V粉末，从而产生致密的样品。
Diode Area Melting (DAM) is an innovative approach to laser powder bed fusion. This research for the first time utilized multiple low wavelength (450 nm) and low power lasers (4 W each) to simultaneously process Ti6Al4V from a powder bed, resulting in high density samples (> 99%). The use of nine lasers perpendicular to the scanning direction allowed for the creation of melt pools with widths larger than 1000 µm, reducing the number of passes within a layer compared to traditional single laser LPBF systems. However, the increase in melt pool width creates challenges related to maintaining uniform melt pool penetration depths, this intern creates issues achieving high density in multi-layer parts. A parameter map based on normalized energy density was created. The research also investigated the effect of variable process conditions (scanning speed, hatch distance, and layer height), normalized energy density on densification, microstructure, and hardness. Implementing a rescanning strategy on each layer reduced average surface roughness and increased density while reducing hardness by approximately 40%. X-ray Diffraction analyses showed that the β phase occurred with increased energy density in as-built samples. Coarser lamellar structures were observed in the lower sections due to slower cooling rates, while finer, more martensite structures were observed towards the top, resulting in a basket-weave type microstructure throughout the sample. Furthermore, the lamellar sub-grains were visible without etching. This innovative technology shows that an array of low-power lasers can melt and fuse Ti6Al4V powder to create dense samples.