JLA Vol:15 Iss:4 (Induction heat treatment of laser welds)

Authors:
Claus Bagger
Joakim Ilsing Sørensen
Flemming O. Olsen
Manufacturing Engineering and Management, Materials and Process Technology, Technical University of Denmark, Building 425, DK-2800 Lyngby, Denmark

In this article, a new approach based on induction heat treatment of flat laser welded sheets is presented. With this new concept, the ductility of high strength steels GA260 with a thickness of 1.8 mm and CMn with a thickness of 2.13 mm is believed to be improved by prolonging the cooling time from 750 to 450 °C. Initially, a simple analytical model was used to calculate the ideal energy contributions from a CO₂ high power laser s...

JLA Vol:19 Iss:4 (Ablation and cutting of silicon wafer and micro-mold fabrication using femtosecond laser pulses)

Authors:
Ying Wang
Nengli Dai
Yuhua Li
Xinlin Wang
Peixiang Lu
Wuhan National Laboratory for Optoelectronics and School of Optoelectronics Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China

Femtosecond laser micromachining of silicon wafer at a relatively higher energy fluence level (>50 J/cm²) is investigated. Laser ablating spots and cutting kerfs are examined by means of charge coupled device camera and scanning electron microscopy. The area of ablated spots increases linearly with increasing the shot number from 1 to 16 and shows saturation with t...

JLA Vol:24 Iss:4 (Femtosecond laser-induced periodic surface structures)

Authors:
J. Bonse
J. Kru¨ger
S. Ho¨hm
A. Rosenfeld
Array

The formation of laser-induced periodic surface structures (LIPSS) in different materials (metals, semiconductors, and dielectrics) upon irradiation with linearly polarized fs-laser pulses (τ ∼ 30–150 fs, λ ∼ 800 nm) in air environment is studied experimentally and theoretically. In metals, predominantly low-spatial-frequency-LIPSS with periods close to the laser wavelength λ are observed perpendicular to the polarization. Under specific irradiation conditions, high-spatial-frequency-LIPSS with sub-100-nm spatial periods (∼λ/10) can be gene...

JLA Vol:5 Iss:1 (Single Pass Laser Cutting of Polymers)

Authors:
R. Patel
G. Baisch
IBM Corporation, GTD, Hopewell Junction, New York

Since the early 1980's discovery of the ability of excimer lasers to etch polymers precisely and cleanly with minimal thermal damage, excimer lasers have been used actively in the semiconductor industry for various manufacturing processes. In the present study a process for laser cutting of polymers has been investigated. A laser beam of controlled cross‐sectional shape is imaged onto a polymer surface. The geometry of the cutting path is controlled by precise movement of a sample mounted on a 2‐axis computer controlled work stage. This type of a process is useful for applications ...

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:14 Iss:1 (Multiple reflection and its influence on keyhole evolution)

Authors:
Hyungson Ki
Pravansu S. Mohanty
Jyotirmoy Mazumder
Center for Laser Aided Intelligent Manufacturing, Department of Mechanical Engineering and Applied Mechanics, The University of Michigan, Ann Arbor, Michigan 48109-2125

In laser drilling and keyhole welding, multiple reflection phenomena determine how the energy is transferred from the laser beam to the workpiece, and, most importantly, all other physics such as fluid flow, heat transfer, and the cavity shape itself depend on these phenomena. In this study, a multiple reflection model inside a self-consistent (or self-evolving) cavity has been developed based on the level set method and ray tracing t...

JLA Vol:18 Iss:2 (Laser ablation of silicon wafer with a water microdrop)

Authors:
Kouki Shimizu
Kunimitsu Takahashi
Photonics and Materials Research Department, Institute of Research and Innovation, 1201 Takada, Kashiwa, Chiba 277-0861, Japan

Hiroshi Morikazu
Nobumori Ogoshi
Koichi Takeyama
DISCO Corporation, 13-11 Omori-Kita 2-chome, Ota-ku, Tokyo 143-8580, Japan

Yoji Wakayama
LINTEC Corporation, 5-14-42 Nishiki-cho, Warabi-shi, Saitama 335-0005, Japan

Tetsuro Obara
Saitama University, 255-Shimo-okubo, Sakura-ku, Saitama-shi, Saitama 338-8570, Japan

We have developed a new laser ablation process using a water-microdrop with a diameter of 70 μm....

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

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

JLA Vol:1 Iss:3 (Laser Welding of Plastics in Low and High Gravity Environments)

Authors:
R. E. Mueller
W. W. Duley
CRESS and Laser Processing Laboratory, York University, Toronto, Ontario, Canada M3J 1P3

S. MacLean
M. Garneau
B. Tryggvason
Canadian Astronaut Office, National Research Council, Ottawa, Ontario, Canada K1A 0R6

W. F. J. Evans
Atmospheric Environment Service, 4905 Dufferin Street, Downsview, Ontario M3H 5T4

Initial results of a series of laser processing experiments performed under the micro‐gravity conditions supplied by NASA's KC‐135 aircraft are presented. Weld morphologies of polypropylene and polyethylene were obtained under both hyper‐ and hy...