JLA Vol:7 Iss:3 (Characterization of chromium bearing surface alloys produced by laser alloying on low carbon steel substrates)

Authors:
G. L. Goswami
Dilip Kumar
A. L. Pappachan
A. K. Grover
K. Sridhar
Array

High‐chromium ferritic alloys were produced on mild steel substrates by laser surface alloying. For this, chromium‐plated mild steel samples were treated with a pulsed Nd:YAG laser (300 W maximum power) by varying the average power level from 21.6 W to 30.0 W. The chromium content of the surface alloys was in the range of 3.0–27.0 wt%, with fairly uniform depth of alloying. Microscopy showed very fine austenite needles within elongated/equiaxed ferrite grains in the laser‐alloyed zone (LAZ). X‐ray diffraction indi...

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:16 Iss:4 (Microstructural aspects of laser dissimilar welds of hard metals to steels)

Authors:
A. Costa
IDMEC, Av. Rovisco Pais, 1049-001 Lisboa, Portugal

L. Quintino
IDMEC, Av. Rovisco Pais, 1049-001 Lisboa, Portugal and Instituto Superior Te´cnico, Secc¸a˜o de Tecnologia Mecaˆnica, Av. Rovisco Pais, 1049-001 Lisboa, Portugal

R. M. Miranda
IDMEC, Av. Rovisco Pais, 1049-001 Lisboa, Portugal and Universidade Aberta, R. Escola Polite´cnica 147, 1269-001 Lisboa, Portugal

Laser beam welding has been widely used in industry in the past decade. Recently, applications in dissimilar welds involving hard metals have been investigated. Hard metals are commonly used in tool manufacturing and this application...

JLA Vol:21 Iss:1 (Local susceptibility of the retina, formation and duration of afterimages in the case of Class 1 laser products, and disability glare arising from high-brightness light emitting diodes)

Authors:
Hans-Dieter Reidenbach
Cologne University of Applied Sciences, Research Laboratory on Medical Technology and Non-Ionizing Radiation, Betzdorfer Str 2, 50679 Koeln, Germany

According to the new European Directive on Artificial Optical Radiation, the employer has to determine the exposure and the assessment of risks and in addition, he shall give particular attention to any indirect effects, such as temporary blinding, when carrying out the risk assessment. Up to now, secondary effects such as temporary blinding have not been regarded in safety standards and there exist but a few data on this topic as far as modern artificial high-brightness (HB) light sources are concerned. Te...

JLA Vol:9 Iss:6 (Scaling laws for thick‐section cutting with a chemical oxygen–iodine laser)

Authors:
A. Kar
J. A. Rothenflue
W. P. Latham

Almost all laser‐assisted materials processing involves melting, vaporization and plasma formation which affect the utilization of laser energy for materials processing. To account for the effect of these phases, an effective absorptivity is defined, and a simple mathematical model is developed for the cutting of thick‐section stainless steel using a high power chemical oxygen—iodine laser (COIL). The model is based on an overall energy balance, and it relates the cutting depth with various process parameters that can be used to predictively scale the laser materials processing performance to ...

JLA Vol:3 Iss:3 (Safety of Medical Excimer Lasers with an Emphasis on Compressed Gases)

Authors:
David H. Sliney
Laser Microwave Division, US Army Environmental Hygiene Agency, Aberdeen Proving Ground, MD 21010‐5422

Terrance N. Clapham
VISX, Inc., 919 Kifer Road, Santa Clara, CA 94086

Excimer lasers which emit short ultraviolet radiation (UVR) are currently being used in experimental and developmental surgical applications. Although UVR exposure is possible, it is not normal in laser angioplasty (cardiovascular surgery) and is insignificant in photokera‐toplasty (ophthalmic surgery). However, significant potential hazards exist with the use of excimer laser gases such as fluorine and HCI. Stringent safeguards for handling and use are ...

JLA Vol:1 Iss:2 (Summary of Laser Plume Effects and Safety Session)

Authors:
Richard P. Felten
Senior Chemist, Radiation Biology Branch, Center for Devices and Radiological Health, Food and Drug Administration

JLA Vol:15 Iss:1 (Microstructure and corrosion behavior of high power diode laser deposited Inconel 625 coatings)

Authors:
J. Tuominen
Laser Application Laboratory, Tampere University of Technology, FIN-33101 Tampere, Finland

P. Vuoristo
T. Ma¨ntyla¨
Institute of Materials Science, Tampere University of Technology, FIN-33101 Tampere, Finland

J. Latokartano
J. Vihinen
Laser Application Laboratory, Tampere University of Technology, FIN-33101 Tampere, Finland

P. H. Andersson
Institute of Production Engineering, Tampere University of Technology, FIN-33101 Tampere, Finland

A series of experiments were performed to investigate the one-step laser cladding of Inconel 625 powder, injected off-axially onto m...

JLA Vol:19 Iss:2 (Welding of titanium and other refractory metals with a free pulse shaping laser)

Authors:
Karsten Richter
Lasag AG, Switzerland

Uwe Reisgen
Wilfried Behr
Forschungszentrum Ju¨lich GmbH, Germany

Ronald Holtz
Lasag AG, Switzerland

Refractory metals are used as construction materials for specific applications. Amongst the refractory metals, titanium has a special status due to its multi-faceted property profile and its comparatively low price. Titanium materials have outstanding properties, such as excellent resistance to corrosion and very high strength at low densities, which lead to their preferred use in chemical engineering and as a structural material in lightweight construction. Due to the high affin...

JLA Vol:24 Iss:2 (Laser dressing of metal bonded diamond blades for cutting of hard brittle materials)

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

In this study, the authors investigate the laser dressing of metal bonded diamond blades by means of laser pulses with different pulse durations and wavelengths. Conventional dressing suffers from excessive blade wear, whereas laser dressing enables precise removal of the bonding metal to generate the required chip space of protruding diamond grains. The challenge for processing this composite material is to find appropriate level of ablation for the bonding metal without damaging the diamond grains thr...