The effect of Ar and He shielding gas on fibre laser weld shape and microstructure in AA 2024-T3
File(s)
Accepted version
Author(s)
Ahn, J
He, E
Chen, L
Dear, JP
Davies, CM
Type
Journal Article
Abstract
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.
Date Issued
2017-07-23
Date Acceptance
2017-07-12
Citation
Journal of Manufacturing Processes, 2017, 29, pp.62-73
ISSN
1526-6125
Publisher
Elsevier
Start Page
62
End Page
73
Journal / Book Title
Journal of Manufacturing Processes
Volume
29
Copyright Statement
© 2017, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Beijing Aeronautical Manufacturing Technology Research Institute
Grant Number
EP/I004351/1
N/A
Subjects
0910 Manufacturing Engineering
Industrial Engineering & Automation
Publication Status
Published