The effect of Ar and He shielding gas on fibre laser weld shape and microstructure in AA 2024-T3
The effect of Ar and He shielding gas on fibre laser weld shape and microstructure in AA 2024-T3
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DOI：
10.1016/j.jmapro.2017.07.011
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发表时间：
2017-10-01
影响因子：
6.2
通讯作者：
Davies, Catrin
中科院分区：
文献类型：
--
作者：
Ahn, Joseph;He, Enguang;Davies, Catrin
研究了氩氦保护气体对2024-T3铝合金激光焊接接头质量、缺陷形成及组织的影响。在4.9 kW的恒定激光功率下，使用连续波（CW）光纤激光器，以3.0-5.0 m/min的行进速度和+4至-4 mm的焦点位置进行全熔透自熔焊接。为了研究这种效果，通过检查焊接质量，在表面和根部焊接宽度、焊接宽度比;存在咬边、毛刺、补强、气孔、裂纹等焊接缺陷。光学金相，能量色散X射线光谱和显微硬度压痕测试焊缝横截面被用来确定如何的化学和物理性质的保护气体和光纤激光器的特性影响整体焊缝几何形状。基于这些结果，可以认为，相对较小的电离对光纤激光诱导羽流的影响增强了焊接过程的稳定性，并降低了小孔形成的阈值功率密度。因此，Ar和He保护气体都可以有效地用于产生高质量的焊缝。然而，在最低的速度，也在最大的焦点位置，较高的电离电位和热导率的氦导致在一个过度的焊缝宽度时，即使使用He，整体焊接质量优于Ar。版权所有（C）2017由Elsevier Ltd代表制造工程师协会发布。All rights reserved.
The effect of using argon and helium shielding gas on weld quality, defect formation and microstructure of laser welded aluminium alloy 2024-T3 was investigated. Full penetration autogenous welds were made at a constant laser power of 4.9 kW using a continuous-wave (CW) fibre laser at travel speeds of 3.0-5.0 m/min and focal positions of +4 to -4 mm. To investigate this effect, a comparison was made between Ar and He by examining the weld quality in terms of the face and root weld width, the weld width ratio; and the presence of welding defects including undercut, underfill, reinforcement, porosity and crack. Optical metallography, energy-dispersive X-ray spectroscopy and micro-hardness indentation testing on weld cross-sections were used to identify how the chemical and physical properties of the shielding gases and the characteristics of the fibre laser affect the overall weld geometry. Based on the results, it was believed that relatively small influence of ionisation on fibre laser induced plume enhanced the welding process stability and lowered the threshold power density for keyhole formation. Both Ar and He shielding gases could therefore, be used effectively to produce good quality welds. However, at the lowest speed and also at the maximum focal position, higher ionisation potential and thermal conductivity of helium resulted in an excessive weld width when He was used even though, the overall weld quality was better than that with Ar. Crown Copyright (C) 2017 Published by Elsevier Ltd on behalf of The Society of Manufacturing Engineers. All rights reserved.