JLA Vol:21 Iss:1 (Enhancing dual phase steel formability by diode laser heat treatment)
Authors:
Edoardo Capello
Barbara Previtali
Politecnico di Milano, Dipartimento di Meccanica Via La Masa 1, I-20156 Milan, ItalyThis paper studies the effect of different typologies of surface treatment by diode laser on the local formability of dual phase steel. An analytical thermal model allowed the temperature and cooling rate curves to be predicted and used to select the process parameter conditions. Microhardness measurements, microstructure observations, mechanical tensile test, and Erichsen cup test allowed the positive effect of the heat treatment on dual phase steel formability to be quantified.
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JLA Vol:21 Iss:1 (Laser cutting ceramics using an unstable fracture technique)
Authors:
Chwan-Huei Tsai
Jian-Shiun Shiu
Department of Mechatronic Engineering, Huafan University, 1, Huafan Road, Shih-ting Hsiang, Taipei Hsien 223, TaiwanThis study proposes a new laser cutting method that uses the unstable fracture technique. In this method, a diamond blade is used to scribe a groove along the desired cutting path in an alumina substrate. A defocused CO2 laser is applied to the substrate surface. As the laser moves a short distance, a short crack is generated through the edge of the substrate. When the laser direction is reversed, a great thermal stress is induced at the crack tip, causing the substrate to break along the scribed line. The...
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JLA Vol:21 Iss:1 (Laser flash photolysis of diazo-2, a caged calcium chelator: The relationship between the extent and rate of smooth muscle relaxation)
Authors:
R. Pelc
University Laboratory of Physiology, Sherrington/Parks Road, Oxford OX1 3PT, United Kingdom and Academy of Sciences, Institutes of Microbiology and Physiology, K Vy´zkumny´m u´stavům (Vi´deňska´) 1083, CZ-14220 Praha 4-Krč, Czech Republic
N. Ishii
University Laboratory of Physiology, Sherrington/Parks Road, Oxford OX1 3PT, United Kingdom
C. C. Ashley
University Laboratory of Physiology, Sherrington/Parks Road, Oxford OX1 3PT, United KingdomRelaxations brought about by laser flash photolysis of diazo-2, a caged calcium chelator, were recorded in the anterior byssus retractor mu...
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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, GermanyAccording 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...
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JLA Vol:21 Iss:1 (Microstructural analysis and oxidation protection behavior of Cr–Ni surface coatings of 347 stainless steel by rapid mirror scanning of a high power CO<sub>2</sub> laser)
Authors:
Jorge A. Ramos-Grez
Departamento de Ingenieri´a Meca´nica y Metalu´rgica, Pontificia Universidad Cato´lica de Chile, Vicun˜a Mackenna 4860, Santiago, Chile
David L. Bourell
University of Texas at Austin, Mechanical Engineering Department, Austin, Texas 78712
Madhav Rao Govindaraju
Karta Technologies, Inc., San Antonio, Texas 78249A surface coating technique that uses a 1 kW CO2 laser beam actuated by two high-speed raster-scanning mirrors was utilized to selectively consolidate predeposited powder coatings consisting of 50%Cr-50% Ni (wt %) over the surface of 347 austenitic stainless st...
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JLA Vol:21 Iss:1 (Potential and limits of chemical enhanced deep cutting of silicon with a coupled laser-liquid jet)
Authors:
A. Fell
K. Mayer
S. Hopman
D. Kray
Fraunhofer Institute for Solar Energy Systems (ISE), Freiburg 79104, GermanyWe present investigations on a new technology with which to cut wafers from a silicon ingot, i.e., the laser chemical processing (LCP), formerly known as laser chemical etching. A coupled laser-liquid jet is used to combine chemical and thermal processes for silicon ablation. We developed a numerical model to simulate heat transport and phase changes due to laser irradiation. Experiments with water and KOH solution as liquid media were performed. The results are discussed and compared with the simulations. It is shown that prob...
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JLA Vol:21 Iss:1 (Two-laser deflashing of heat sinks in integrated circuit packages)
Authors:
W. D. Song
Q. Xie
Data Storage Institute, Agency of Science, Technology and Research, DSI Building, 5, Engineering Drive 1, Singapore 117608, SingaporeDuring the plastic packaging process, mold flash is usually formed on a heat sink. In order to keep efficient heat transfer from the integrated circuit device to the exterior environment, the mold flash must be removed from the heat sink surface. In this paper, we demonstrate that a Nd:YAG laser deflashing is only available to remove thin flash of a few micrometers from heat sinks and cannot remove thick flash without damage to the heat sink, both from experimental and numerical analysis. Based on optical and ther...
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JLA Vol:21 Iss:1 (Visualization of events inside kerfs during laser cutting of fusible metal)
Authors:
Peter Yudin
Oleg Kovalev
Khristianovich Institute of Theoretical and Applied Mechanics, Novosibirsk, 630090, RussiaThe subject of the research is mechanism of melt removal and striated roughness generation. Being the main obstacle limiting laser cutting process performance, these phenomena are widely discussed. Available theoretical descriptions are not conclusive, as they have nothing to be verified with. High temperatures and narrowness of the kerf severely limit visual access at a real facility. Observation will become possible if one wall of the kerf is made of glass. This possibility is utilized in present experiments, which reproduce the process at low tem...
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JLA Vol:21 Iss:2 (Corrosion performance and restoration of laser-formed metallic alloy sheets)
Authors:
Z. Liu
C. Guzma´n
H. Liu
A. Anacleto
T. Francisco
M. Abdoalshafie
L. Ma
O. Abodunrin
P. SkeldonPrevious studies of laser forming have been focused on understanding the laser forming mechanisms, investigating the effects of important laser process parameters on deformed shape, and modeling the forming process. Although microstructures and mechanical properties have received some attention, no work has addressed corrosion behavior of laser-formed components. However, laser forming is a thermal process with substantial thermal cycles required; sensitization of microstr...
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JLA Vol:21 Iss:2 (Laser percussion drilling modeling utility)
Authors:
Tom A. Eppes
Ivana M. Milanovic
University of Hartford, 200 Bloomfield Avenue, West Hartford, CT 06117, USA
Devdas Shetty
Lawrence Technological University, 21000 West Ten Mile Road, Southfield, MI 48075, USALaser percussion drilling is widely used in the aerospace industry to produce cooling holes in jet engine components. A variety of theoretical models have been developed to predict the outcome of the drilling process. However, to utilize these models often requires sophisticated software to perform the required numerical analyses. A simple and easy-to-use computer utility Drilling Routine for Estimating, Analyzing, and Modeling (DRE...
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