JLA Vol:26 Iss:1 (Geometrical aspects of hot cracks in laser-arc hybrid welding)

Authors:
Greger Wiklund
Department of Applied Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, Sweden

Odd Akselsen
SINTEF Materials and Chemistry, P. O. Box 4760 Sluppen, NO-7465 Trondheim, Norway

Arve J. So&slash;rgjerd
Kvaerner Verdal AS, Material Department, Hamnevegen 7, NO-7650 Verdal, Norway

Alexander F. H. Kaplan
Department of Applied Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, Sweden

Hot cracks were frequently found in double sided laser-arc hybrid welding thick section (20 mm) low carbon steel. Other research has usually investigat...

JLA Vol:26 Iss:1 (Investigation on reducing distortion by preheating during manufacture of aluminum components using selective laser melting)

Authors:
Damien Buchbinder
Wilhelm Meiners
Norbert Pirch
Konrad Wissenbach
Fraunhofer Institute for Laser Technology (ILT), Aachen 52074, Germany

Johannes Schrage
Chair for Laser Technology, RWTH Aachen University, Germany 52024, Aachen

The additive manufacturing process selective laser melting (SLM) can be used to directly produce functional components made out of metal. During the construction process, however, thermally induced residual stress occurs due to the layered build-up and the local input of energy by means of a focused laser beam, which can lead to distortion of the component or sections of the component itself....

JLA Vol:26 Iss:1 (Laser absorptivity on wavy molten metal surfaces: Categorization of different metals and wavelengths)

Authors:
A. F. H. Kaplan
Department of Engineering Sciences and Mathematics, Luleå University of Technology, S-971 87 Luleå, Sweden

The absorptivity of a laser beam interacting at grazing incidence with the processing front during laser welding, cutting, or drilling depends on the metal to be processed and on the laser wavelength. The absorptivity on a smooth processing front is homogeneously governed by the angle-dependent operating range of the corresponding Fresnel-curve. In contrast, a wavy processing front strongly modulates the absorptivity across the surface. The calculated absorptivity modulation is presented for five different metals and four laser wavelengths. A ...

JLA Vol:26 Iss:1 (Microstructure characterization and mechanical properties of laser-welded copper and aluminum lap joint)

Authors:
Zhiqing Xue
Shengsun Hu
Junqi Shen
Di Zuo
School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China

Elijah Kannatey-Asibu
Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2125

The microstructure in the intermediate layer of a laser-welded Cu–Al lap joint was examined metallographically. Tensile shear test was performed, and fracture surface analysis was also performed using scanning electron microscopy with energy dispersive spectroscopy. Results showed that there were several different zones with diverse characteristics of morphology and comp...

JLA Vol:26 Iss:1 (Performance enhancement of aluminum infrared laser welding by preconditioning with nanosecond laser pulses)

Authors:
Philipp von Witzendorff
Anas Moalem
Uwe Stute
Ludger Overmeyer
Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover, Germany

We condition the welding zone of the aluminum surface with nanosecond laser pulses prior to welding with infrared laser radiation to increase the process efficiency and weld quality. The high reflectivity of aluminum for infrared laser radiation (95% at 1064 nm) leads to poor process efficiency of aluminum laser welding processes. To increase the workpiece's absorptivity, the welding zone is conditioned with nanosecond laser pulses at a wavelength of 532 nm. The samples are nonalloy, 0.5 mm thick alum...

JLA Vol:26 Iss:1 (Periodic antireflection surface structure fabricated on silicon by four-beam laser interference lithography)

Authors:
Z. Zhang
CNM and JR3CN, Changchun University of Science and Technology, Changchun 130022, China and CHO, Changchun Observatory, National Astronomical Observatory, CAS, Changchun 130117, China

Z. Wang
D. Wang
CNM and JR3CN, Changchun University of Science and Technology, Changchun 130022, China and JR3CN, University of Bedfordshire, Luton LU1 3JU, United Kingdom

Y. Ding
CNM and JR3CN, Changchun University of Science and Technology, Changchun 130022, China

Silicon surface structures with excellent antireflection property arouse wide interest. Chemical and physical methods such as femtosecond, nanosecond, and picosecond la...

JLA Vol:26 Iss:1 (Surface tension generated defects in full penetration laser keyhole welding)

Authors:
Ingemar Eriksson
John Powell
Alexander F. H. Kaplan
Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, Sweden

During laser keyhole welding of thin plates, the melt pool is relatively wide compared to the plate thickness. Under certain conditions, an elongated keyhole can be created and a permanent hole is sometimes left in the weld seam. The generation of such holes is determined by surface tension effects in the melt which can generate a self-sustaining geometry at the rear of the melt pool. The geometry of the shape is known as a catenoid and has clear geometrical limits.

JLA Vol:26 Iss:1 (Two-dimensional simulation of laser ablation with 235 nanosecond pulses)

Authors:
Sousan Ghalamdaran
Iranian National Centre for Laser Science and Technology (INLC), PO Box 14665-576 Tehran, Iran and Department of Physics, Amir Kabir University of Technology, PO Box 15875-4413 Tehran, Iran

Parviz Parvin
Department of Physics, Amir Kabir University of Technology, PO Box 15875-4413 Tehran, Iran

Mohamad Javad Torkamany
Jamshid Sabbagh Zadeh
Iranian National Centre for Laser Science and Technology (INLC), PO Box 14665-576 Tehran, Iran

A two-dimensional thermal model of nanosecond pulsed laser ablation is developed to describe the physical processes, the plasma absorption, the crater profile, and the temp...

JLA Vol:3 Iss:1 (Cutting of Al‐Alloys Using High‐Pressure Coaxial Nozzle)

Authors:
B. Biermann
S. Biermann
H. W. Bergmann
Forschungsverbund Lasertechnologie Erlangen (FLE), Martensstr. 5, 8520 Erlangen, West Germany

Aluminum alloys are used extensively in aerospace structures because of their high strength‐to‐weight characteristics. Unfortunately, these alloys are difficult to cut by laser processing. This behavior stems from: 1) their affinity for atmospheric gases, 2) their tendency to form high melting point reaction products and 3) the marked difference between their solidus and liquidus temperatures, which leads to formation of a mushy zone during cutting. This paper describes the results of a program directed t...

JLA Vol:3 Iss:1 (Developments in Medical Applications)

Authors: