JLA Vol:22 Iss:4 (Effect of laser and laser hybrid welding on the corrosion performance of a lean duplex stainless steel)

Authors:
Elin M. Westin
Outokumpu Stainless AB, Avesta Research Center, P.O. Box 74, 774 22 Avesta, Sweden

Anna Fellman
Laser Processing Laboratory, Lappeenranta University of Technology, Tuotantokatu 2, 53850 Lappeenranta, Finland

The use of duplex stainless steel increases steadily worldwide and the fluctuations in nickel price the recent years have contributed to further growth. The lean duplex grade Outokumpu LDX 2101^® (EN 1.4162, UNS S32101) has a low nickel content and is alloyed with nitrogen and manganese to give a balanced microstructure. It means that good austenite formation is obtained even when laser welding autogenously (without fille...

JLA Vol:16 Iss:3 (Laser microspot welding of copper)

Authors:
S. Amorosi
Th. Sidler
R. P. Salathe´
Advanced Photonics Laboratory, Ecole Polytechnique Fe´de´rale de Lausanne, Switzerland

H. P. Schwob
J. Hertzberg
LASAG AG, Thun, Switzerland

We describe a novel procedure for highly reliable microspot welding of copper based on a calibrated on-line reflectivity measurement. This parameter is used to control the laser power slope and the weld spot diameter. Reliable welds are obtained without the need of other active control mechanisms. The new technique allows realizing welds with a diameter close to the laser beam waist and leads to a reduction in the relative ...

JLA Vol:7 Iss:2 (Fraunhofer‐Institut fu¨r Lasertechnik)

Authors:
Eckhard Beyer
Fraunhofer‐Institut fu¨r Lasertechnik, Aachen, Germany

JLA Vol:20 Iss:4 (Tailored hybrid blank production—New joining concepts using different solders)

Authors:
C. von der Haar
L. Engelbrecht
O. Meier
A. Ostendorf
H. Haferkamp
Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover, Germany

A consistent lightweight concept necessitates the combination of different lightweight materials. Because of the significant weight reduction, multimaterial design is becoming more and more interesting for the transportation industry. Mixed material concepts are partially limited because of the insufficient deformation behavior of the joining seams. To overcome this limitation, a brazing process has been developed in which aluminium and steel can be joined, with an enhanced deformation beha...

JLA Vol:14 Iss:4 (Determining source size from diode laser systems)

Authors:
Wesley J. Marshall
U.S. Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Ground, Maryland 21010-5403

Although hazard classification is performed at predefined distances, the maximum permissible exposure (MPE) for extended-source diode lasers decreases as the distance from the laser increases. The MPE depends on the apparent angular subtense of the source, which is simply the magnified image of the emitting diode. Small diameter beams require special consideration.

JLA Vol:9 Iss:4 (Dual wavelength laser beam alloying of aluminum alloy for enhanced corrosion resistance)

Authors:
Z. Liu
K. G. Watkins
W. M. Steen
R. Vilar
M. G. Ferreira

Aluminum alloys are known for their poor resistance to localized attack and, in particular, for pitting in chloride‐containing electrolytes. In this paper, improvement of the pitting corrosion resistance of 2014‐T6 aluminum alloy has been investigated by means of laser surface alloying of Cr into the substrate. Since aluminum is a highly reflective and thermally conductive material, it is often difficult to process with laser beams. Oxide films on the surface can prevent surface alloying as with the case of Cr alloying into aluminum by in‐situ...

JLA Vol:18 Iss:4 (Cutaneous sensation threshold for 3.8 μm radiation from a short duration pulsed laser on the calves of human subjects: A pilot study)

Authors:
Thomas E. Johnson
Michael J. Roy
Department of Environmental and Radiological Health Sciences, Colorado State University, 1618 Campus Delivery, Fort Collins, Colorado 80528 and Department of Medicine, School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, Maryland 20814

The objective of this study was to determine the threshold for sensing a 3.8 μm laser on the skin. The identification of the skin sensation threshold for invisible lasers is useful in providing scientific guidance to the safety community regarding accidental skin exposures. Knowledge of the level of sensation of lasers might be used to s...

JLA Vol:4 Iss:1 (The Impact of European Standards, Directives and the CE Mark)

Authors:
A. Roy Henderson
Bioptica, St. John's Innovation Park, Cambridge U.K.

JLA Vol:25 Iss:5 (Numerical and experimental study of the effect of groove on plasma plume during high power laser welding)

Authors:
Cai Yan
Xie Wen-Jing
Wu Yue
Sun Da-Wei
Wu Yixiong
Shanghai Jiao Tong University, Dongchuan Road 800, Shanghai 200240, China and Shanghai Key Laboratory of Materials Laser Processing and Modification, Shanghai 200240, China

The influence of groove on the static feature and dynamic behavior of plasma plume during high power CO₂ laser welding process was studied using a hydrodynamic three-dimensional model and corresponding experiments. The temperature, composition, and velocity of plasma plume along the incident path of laser beam were computed. The static morphology of plasma plume was analyzed through both models ...

JLA Vol:15 Iss:3 (Steady-state laser cutting modeling)

Authors:
Ce´dric Mas
Re´my Fabbro
CLFA, 16 bis Avenue Prieur de la Côte d’Or, 94114 Arcueil Cedex, France

Yannick Goue´dard
OPTIS, ZE la Farlède, BP 275, 83078 Toulon Cedex 9, France

We present a global self-consistent model of the laser cutting process where we have taken into account the main parameters of the process that are the laser beam intensity distribution, the thermal phenomena controlling the melt parameters, the fluid, both cutting gas and melt hydrodynamics, and the local equilibrium of the geometry of the cutting front. This steady state approach provides us with different fluid velocities, surface ...