JLA Vol:17 Iss:1 (Microstructural characterization of dissimilar laser weld between austenitic and ferritic stainless steels)

Authors:
Rakesh Kaul
P. Ganesh
A. K. Nath
Industrial CO2 Laser Section, Centre for Advanced Technology, P. O. CAT, Indore 452 013, India

The present work involved microstructural characterization of thin sheet dissimilar laser welds between type 304 austenitic stainless steel and stabilized 17% Cr ferritic stainless steel and their comparison with welds produced by autogenous gas tungsten arc welding (GTAW). Low heat input of laser welding (LW) effectively reduced the size of fusion zone (FZ) and heat affected zone (HAZ). LW with focused laser beam (LB), preferentially displaced towards austenitic stainless steel (ASS), produced FZ with uniform and highly ref...

JLA Vol:25 Iss:4 (On the exposure limits for extended source multiple pulse laser exposures)

JLA Vol:21 Iss:3 (Infrared observations and finite element modeling of a laser transmission welding process)

Authors:
L. S. Mayboudi
A. M. Birk
G. Zak
Mechanical and Materials Engineering, Queen’s University, Kingston, Ontario K7L 3N6, Canada

P. J. Bates
Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario K7K 7B4, Canada

Laser transmission welding (LTW), a technique to join thermoplastic components, involves a laser beam passing through a laser-transmitting part and then being absorbed by the laser-absorbing part at the weld interface. To form a strong bond, it is important that the weld interface be exposed to sufficient heat to melt the polymer without degrading it. A lap-joint geometry was investigated and the...

JLA Vol:24 Iss:3 (Laser cladding for railway repair and preventative maintenance)

Authors:
Adam Clare
Olusola Oyelola
Janet Folkes
Peter Farayibi
Innovative Manufacturing Processes Group, Manufacturing Division, Faculty of Engineering, The University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom

Rolling contact fatigue, amongst other mechanisms of wear, between railway track and train wheel ensures that periodic replacement of worn track and other key components such as switches must be undertaken. The cost associated with repairing/replacing track is significant. This places a financial burden upon the rail network provider, creates a significant carbon footprint associated with remanufacture of track, an...

JLA Vol:6 Iss:4 (Erratum: Excimer laser processing of Ti–6Al–4V)

Authors:
J. A. Folkes
K. Shibata
Nissan Motor Co. Ltd, Materials Research Laboratory, Central Engineering Laboratories, 1, Nasushima‐cho, Yokosuka 237, Japan

JLA Vol:15 Iss:2 (Plasma assisted laser surface alloying)

Authors:
M. H. McCay
C. M. Sharp
J. A. Hopkins
The Center for Laser Applications, The University of Tennessee Space Institute, Tullahoma, Tennessee 37388

B. Szapiro
The Department of Physics, University of the South, Sewanee, Tennessee

T. D. McCay
The Center for Laser Applications, The University of Tennessee Space Institute, Tullahoma, Tennessee 37388

The combination of plasma arc with a Nd:YAG laser during surface alloying produces a synergistic effect which significantly increases the depth of the melt pool beyond that expected by a summation of the individual depths. Incremental increases in laser power produce ...

JLA Vol:19 Iss:3 (Femtosecond pulsed laser microfabrication of SiC MEMS microgripper)

Authors:
Monica Vendan
Pal Molian
Mechanical Engineering Department, Iowa State University, Ames, Iowa 50011

We report the capability of an ultrafast laser to pattern an electrostatic-comb-drive microgripper in the chemically difficult-to-etch 3C-SiC thin films. A microgripper with overall dimensions 1.2 mm×0.35 mm and a gap of 20 μm was designed and fabricated for the purpose of grasping and transporting microscale objects in hostile and harsh environments. Atmospheric pressure chemical vapor deposition was used to deposit thin films (∼2 μm) of 3C-SiC on 〈100〉 silicon substrates. A Ti:sapphire laser with 120 fs pulse wid...

JLA Vol:8 Iss:6 (Laser surface alloying of magnesium base alloys)

Authors:
R. Galun
A. Weisheit
B. L. Mordike
Institut fu¨r Werkstoffkunde und Werkstofftechnik, Technische Universita¨t Clausthal, Agricolastraße 6, D‐38678 Clausthal‐Zellerfeld, Germany

The feasibility of the laser surface alloying of magnesium base alloys with aluminum, copper, nickel and silicon has been shown in this work. By laser alloying with these elements, using a 5 kW CO₂‐laser, the hardness of several magnesium base alloys can be increased to values above 250 HV_0.1. Melted depths from 700–1200 μm and alloying contents from 15–55 at % were achieved. The wear resistance of ...

JLA Vol:1 Iss:4 (Optical Methods in Flow Visualization)

Authors:
Wen‐Jei Yang
Yi Chen
Department of Mechanical Engineering and Applied Mechanics, The University of Michigan, Ann Arbor, Michigan 48109

Optical techniques for flow visualization are presented, including light‐sheet flow visualization, shadowgraphy, schlieren method, interferometry, holography, speckle photography, laser‐induced fluorescence and thermography. The principles of these methods are briefly described and the examples of their applications to flow visualization are given.

JLA Vol:17 Iss:4 (Faster and damage-reduced laser cutting of thick ceramics using a simultaneous prescore approach)

Authors:
V. Pereles-Santiago
M. Washington
P. Brugan
G. Cai
R. Akarapu
S. Pulford
A. E. Segall
The Pennsylvania State University, University Park, Pennsylvania 16802

Laser machining of structural ceramics is increasingly gaining acceptance as an alternative to traditional machining methods. However, despite the great promise of lasers for a variety of cutting and drilling procedures, premature fractures and prohibitively low cutting speeds are still among the greatest obstacles encountered, particularly when thick cross sections are involved. While many factors contribute to the fractures encountered during ...