Laser Welding
This chapter describes characteristics of laser welding, features of main lasers used for welding, factors affecting weld penetration, laser welding phenomena including behavior of laser-induced plume, keyhole behavior, and melt flows in a molten pool dur
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Laser Welding Seiji Katayama
Abstract This chapter describes characteristics of laser welding, features of main lasers used for welding, factors affecting weld penetration, laser welding phenomena including behavior of laser-induced plume, keyhole behavior, and melt flows in a molten pool during laser welding. It also refers to elucidation of formation of welding defects, preventive procedures of such defects, and examples of laser joining results of dissimilar metals and metal to plastic or CFRP, monitoring and adaptive control results during welding, and industrial applications as a recent trend for laser welding.
Keywords Laser welding CO2 laser YAG laser Fiber laser Diode laser Fiber delivery Welding phenomena Welding defects Laser-induced plume Deep penetration Welding conditions Dissimilar metals joining Monitoring Industrial applications
10.1
Characteristics of Laser Welding
Welding is the most versatile and realistic joining method applicable to the construction of products in many industrial fields. A laser is one of the high-power-density or the high-energy-density heat sources. Therefore, “laser welding” is recognized as an advanced process to join materials with a laser beam of high power and high-energy density. The power density distribution of a laser beam and the consequent geometry of a weld bead are schematically shown in Fig. 10.1, in comparison with the profiles of arc, plasma, and electron beam. Welding with an arc is most widely used, thanks to cheap apparatuses and easy production of good joints, but the penetration of an arc weld bead is not so deep. Plasma welding can produce slightly deeper penetration than arc welding due to higher power/energy density. An electron beam can produce the deepest weld S. Katayama (&) Osaka University, Suita, Japan e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2019 Y. Setsuhara et al. (eds.), Novel Structured Metallic and Inorganic Materials, https://doi.org/10.1007/978-981-13-7611-5_10
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Power density Power density
Fig. 10.1 Power densities for typical welding heat sources, and geometry of weld beads obtained at respective densities
Penetration
Schematic
Laser Electron beam Plasma Arc welding welding welding welding
bead, but vacuum conditions, a chamber for X-ray protection for human beings, and sometimes demagnetization for steel plates are required. On the other hand, a laser beam of high power/energy density can also produce a deep and narrow penetration weld easily in the shielding gas such as helium (He), argon (Ar), or sometimes nitrogen (N2) under the air environment. Moreover, much deeper weld beads can be produced with a laser beam at low welding speeds even in low vacuum. The depths of laser welds are almost equal to those of electron beam welds. Among all the welding processes, laser welding can produce a variety of joints of metals or plastics ranging from very thin sheets of about 0.01 mm thickness to thick plates of about 100 mm thickness, and has g
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