JLA Vol:8 Iss:2 (Laser materials processing at Sandia National Laboratories)

Authors:
James L. Jellison
Michael J. Cieslak
Sandia National Laboratories, Albuquerque, NM 87185, U.S.A.

This paper describes the laser materials processing capabilities at Sandia National Laboratories. Some of the advances in the understanding of various aspects of laser materials processing which have been made by the laser materials processing team at Sandia are discussed.

JLA Vol:8 Iss:2 (Recent progress in laser surface treatment: <emph type="4">II</emph>. Adopted processing for high efficiency and quality)

Authors:
W. Bloehs
B. Gru¨nenwald
F. Dausinger
H. Hu¨gel
Institut fu¨r Strahlwerkzeuge, Universita¨t Stuttgart, Pfaffenwaldring 43, 70569 Stuttgart, Germany

In Part I of this contribution, energy coupling and transport mechanisms were considered in detail. The second part concentrates on the effect of the spatial distribution of the energy in the laser beam, which will be discussed in connection with applications of laser surface technologies. Along these lines, a variety of beam shaping facilities is presented for laser hardening and cladding. Their purpose is to adapt the irradiated area to the workpiece ge...

JLA Vol:8 Iss:2 (Enhancement of adhesion in coated steels through excimer laser surfacing)

Authors:
M. Olfert
R. E. Mueller
W. Duley
T. North
J. Hood
D. Sakai

Galvanize and galvanneal steel sheet are used extensively by the automotive industry. Through a process of excimer laser surface treatment, we have succeeded in significantly enhancing the adhesion characteristics of these coated steels. Preliminary adhesion tests have been carried out via simple ‘T’ peel testing, using a hot melt nylon resin as the adhesive substrate. The peel test results indicate that, for particular processing conditions, enhanced adhesion exceeding the cohesive strength of the nylon adhesive can be obtained. The results...

JLA Vol:8 Iss:2 (Low power laser heat treatment to improve fatigue life of low carbon steel)

Authors:
David E. Fly
J. T. Black
Ben Singleton

An industrial laser cutting machine tool was used to harden 1117 and 1144 steel to examine effects on fatigue life. Transformation hardening leaves residual compressive stresses at the surface, which greatly enhance fatigue life in addition to increasing the hardness. The laser, which creates localized heating, allows faster cooling rates than conventional heat treatment methods. As a result, the application of the laser facilitates the hardening of low carbon steel which is not hardenable by conventional methods.

JLA Vol:8 Iss:2 (Trepan drilling of fuel injection nozzles with a TEM₀₀ Nd:YAG slab laser)

Authors:
H. Rohde
E. Meiners

Holes of 160 μm diameter were trepan drilled in fuel injection nozzles of 1 mm thickness by means of a TEM₀₀ fundamental mode Nd:YAG slab laser. Two different types of holes have been trepan drilled: at an angle of 90°, and at an angle of 60° to the metal surface. The influence of nozzle distance, focal position, gas pressure, pulse repetition frequency and trepanning velocity on the hole diameter and on the conicity are investigated. A diameter accuracy of ±10 μm and a conicity of 3&percnt; were achieved. One hole is drilled in 7–25 seconds in dependence of the drilling strategy.

JLA Vol:8 Iss:3 (Theoretical and experimental studies of thick&hyphen;section cutting with a chemical oxygen&ndash;iodine laser (COIL))

Authors:
A. Kar
J. E. Scott
W. P. Latham

A simple mathematical model of thick&hyphen;section stainless steel cutting with a high power chemical oxygen–iodine laser (COIL) is presented and compared with experimental results obtained with a 10&hyphen;kilowatt COIL at the U.S. Air Force's Phillips Laboratory. This model uses a lumped&hyphen;parameter technique to relate the cutting kerf depth with various process parameters and can be used to predict scaled laser materials processing performance to very thick sections. The model is similar to an empirical model developed by researchers in Japan, but includes predictive capabilities for thick metal cutting...

JLA Vol:8 Iss:3 (Laser shock processing of materials, physical processes involved and examples of applications)

Authors:
P. Peyre
R. Fabbro
L. Berthe
C. Dubouchet

Laser shock processing (LSP) consists of irradiating a metallic target with a short (about 20 ns) and intense (>10¹³W m⁻²) laser light in order to generate, through a high pressure surface plasma (>1 GPa), a plastic deformation and a surface strengthening within materials. This paper initially reviews the physical processes involved in the analytical modeling of the generation pressure mechanism in a confined plasma regime. Limiting factors such as the dielectric breakdown in the confining medium are also discussed together with current research directions aimed...

JLA Vol:8 Iss:3 (Parametric studies of cutting zircaloy&hyphen;2 sheets with a laser beam)

Authors:
Swati Ghosh
B. P. Badgujar
G. L. Goswami
Atomic Fuels Division, Bhabha Atomic Research Centre, Trombay, Bombay &hyphen; 400 085, India

The highly reactive and pyrophoric nature of zirconium alloys limits the use of conventional thermal sources (e.g., plasma arc cutting, oxygen flame cutting, etc.) for the cutting and drilling of these alloys. In this context, a highly coherent laser beam provides a good alternative for the cutting and drilling. In the present paper, laser beam cutting of zircaloy&hyphen;2 sheets of 1.1 mm and 0.74 mm thickness is performed using a 300 W average power pulsed Nd:YAG laser. Pulse energy, pulse repetition rate, nozzle ga...

JLA Vol:8 Iss:3 (A study of laser&hyphen;based removal of polymethylmethacrylate bone cement)

Authors:
W. O'Neill
P. Kapadia
T. Thomas

Complications are often produced with the removal of bone cement from the femoral cavity in the treatment of a failed hip prosthesis. Apart from being slow and difficult the conventional process runs the risk of producing damage to the femur. Ultrasonic techniques have been suggested to achieve these ends but removal of the cement by this approach is not entirely easy. The alternative laser&hyphen;based approach would seem to have significant advantages over conventional techniques. The laser is capable of delivering energy to a specific region or surface under close control. The choice of laser is determined by its a...

JLA Vol:8 Iss:3 (Commonwealth of Independent States (CIS) laser scene and Laser Association (LAS) activities)

Authors:
Ivan B. Kovsh
LAS Headquarters, Moscow, Rozhdestvenkastr, 27, 117485, Russia