An analysis of the laser material interaction in the welding of steel using a cw CO laser
- Univ. of Essex (United Kingdom); and others
A continuous CO laser has been used to study welding in 0.8 and 6.0 mm thick C/Mn steel for laser powers in the range 0.7 to 1.8 kW. Experimental data including penetration depths, weld widths, and in some cases weld pool profiles, has been obtained using both argon and helium shielding gas. The interaction of the laser light with the weld specimen is analyzed here by means of an integrated keyhole and weld pool model. The laser generated plume is represented as a point heat source whose strength involves effectively the only adjustable parameter in the model. This parameter was chosen by matching the calculated weld width at the top of the specimen to its corresponding experimental value. The remaining aspects of the model involve the absorption of laser light on the keyhole wall and in the keyhole plasma. The method has been developed previously for cw CO{sub 2} laser material processing. The very restricted nature of the keyhole traps the radiation and causes the walls of the keyhole to behave like a black body. Very satisfactory agreement was obtained between the mathematical model and experiment for both penetration depths as well as weld bead shapes. In general terms cw CO and CO{sub 2} lasers appear to perform similarly in their interaction with metals except that CO lasers tend to produce smaller plumes which are easier to disrupt using the shielding gas. It was found that this could lead to interesting effects. In particular it was found that in the case of CO welding that deeper penetration was achievable using argon as the shielding gas than is possible using helium. This is because argon is a heavier gas than helium and therefore better at displacing the plume. The controllability of CO laser generated plumes could constitute a significant advantage of CO lasers over their CO{sub 2} counterparts under conditions where plume effects tend to be a problem such as in the welding of very thick section materials using very low weld translation speeds.
- OSTI ID:
- 539328
- Report Number(s):
- CONF-961073-; TRN: 97:003387-0054
- Resource Relation:
- Conference: ICALEO `96: 15. international congress on applications of lasers and electro-optics, Detroit, MI (United States), 14-17 Oct 1996; Other Information: PBD: 1996; Related Information: Is Part Of Proceedings of the laser materials processing conference - ICALEO `96. Volume 81; PB: 971 p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
A mathematical model of ablation in the keyhole and droplet formation in the plume in deep penetration laser welding
The Effect of Ar and N2 Shielding Gas on Laser Weld Porosity in Steel, Stainless Steel, and Nickel