Microstructure and Residual Stresses of Laser Structured Surfaces

A new approach to structure metallic surfaces with laser radiation is structuring by remelting. In this process no material is removed but reallocated by melting. The laser power was adapted linearly to the increasing laser beam diameter for laser remelted (polished) samples. A carbon depleted area could be found close to the remelted zone accompanied with a local minimum in hardness. The surface residual stresses tend from tensile to compressive with increasing laser beam diameter/laser power and number of repetitions for laser structured and laser remelted samples. The residual stresses are a result of combined shrinkage (tensile) and transformation (compressive) stresses.

Download Full-text

Analysis of Roughness and Heat Affected Zone of Steel Plates Obtained by Laser Cutting

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.974.169 ◽

2014 ◽

Vol 974 ◽

pp. 169-173 ◽

Cited By ~ 5

Author(s):

Imed Miraoui ◽

Mohamed Boujelbene ◽

Emin Bayraktar

Keyword(s):

Surface Roughness ◽

Laser Beam ◽

Heat Affected Zone ◽

Laser Power ◽

Laser Cutting ◽

Major Effect ◽

Steel Plates ◽

Beam Diameter ◽

Laser Beam Diameter ◽

Cut Surface

In the present study, high-power CO2 laser cutting of steel plates has been investigated and the effect of the input laser cutting parameters on the cut surface quality is analyzed. The average roughness of the cut surface of the specimens, produced by different laser beam diameter and laser power, were measured by using roughness tester. The scanning electron microscopy SEM is used to record possible metallurgical alterations on the cut edge. The aim of this work is to investigate the effect of laser beam diameter and laser power on the cut surface roughness and on the heat affected zone width HAZ of steel plates obtained by CO2 laser cutting. An overall optimization was applied to find out the optimal cutting setting that would improve the cut surface quality. It was found that laser beam diameter has a negligible effect on surface roughness but laser power had major effect on roughness. The cut surface roughness decreases as laser power increases. Improved surface roughness can be obtained at higher laser power. Also, laser beam diameter and laser power had major effect on HAZ width. It increases as laser power increases.

Download Full-text

Effect of Laser Beam Diameter on Cut Edge of Steel Plates Obtained by Laser Machining

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.467.227 ◽

2013 ◽

Vol 467 ◽

pp. 227-232 ◽

Cited By ~ 4

Author(s):

Imed Miraoui ◽

Mouna Zaied ◽

Mohamed Boujelbene

Keyword(s):

Laser Beam ◽

Laser Cutting ◽

Steel Plates ◽

Beam Diameter ◽

Power Laser ◽

Laser Beam Diameter ◽

Machined Surface ◽

Cut Edge ◽

Thermal Influence ◽

Cut Surface

Laser cutting is a thermal process which is used contactless to separate materials. In the present study, high-power laser cutting of steel plates is considered and the thermal influence of laser cutting on the cut edges is examined. The microstructure and the microhardness of the cut edge are affected by the input laser cutting parameter: laser beam diameter. The aim of this work is to investigate the effect of the laser beam diameter on the microhardness beneath the cut surface of steel plates obtained by CO2 laser cutting. The cut surface was studied based on microhardness depth profiles beneath the machined surface. The results show that laser cutting has a thermal effect on the surface microstructure and on the microhardness beneath the cut section. Also the microhardness of the hardening zone depends on the laser beam diameter.

Download Full-text

Experimental Study of Forming Rene95 Alloy Parts by Laser Cladding

10.1115/imece2001/med-23340 ◽

2001 ◽

Author(s):

Qilin Deng ◽

Dejin Hu ◽

Jingyu Pei ◽

Wenwu Zhang ◽

Y. Lawrence Yao

Keyword(s):

Experimental Study ◽

Laser Cladding ◽

Laser Power ◽

Alloy Powder ◽

High Strength ◽

Scanning Speed ◽

Main Process ◽

Beam Diameter ◽

Laser Beam Diameter ◽

Metal Parts

Abstract In this paper, experimental study of forming metal parts by laser cladding Rene95 alloy powder was reported. The influence of main process parameters, such as laser power, scanning speed and laser beam diameter, on the thickness, width and the angle of the laser cladding track was investigated. The microstructures of laser cladding parts were studied and compared with those of common casting parts. The obtained Rene95 metal parts formed by laser cladding are dense and of high strength.

Download Full-text

An Evaluation of the use of Laser-Vibration Melting to Increase the Surface Roughness of Metal Objects

Archives of Metallurgy and Materials ◽

10.1515/amm-2015-0005 ◽

2015 ◽

Vol 60 (1) ◽

pp. 33-39 ◽

Cited By ~ 5

Author(s):

B. Grabas

Keyword(s):

Surface Roughness ◽

Laser Beam ◽

Laser Power ◽

Surface Structures ◽

Scanning Velocity ◽

New Approach ◽

Practical Applications ◽

Microscopic Evaluation ◽

Heating Surfaces ◽

Laser Beam Scanning

Abstract This paper presents preliminary, experimental results of a new, hybrid method of increasing the surface roughness of metal objects. In this new approach, metal objects are melted with a mobile laser beam while they are being rotated. A vibration generator provides circular vibrations with an amplitude of 3 mm, and the vibration plane is perpendicular to the moving laser beam. The melting tests were performed using flat carbon steel samples at a predetermined frequency of circular vibrations. The effects of laser power and laser beam scanning velocity on the melted shapes were studied. All laser melting procedures were performed at a vibration frequency of 105 Hz. The melted samples were subjected to microscopic evaluation and the Ra parameter, which characterises mean roughness, was measured using a profilometer. Melting metal samples with physically smooth surfaces (Ra = 0.21 µm) resulted in surface structures of varied roughness values, with Ra ranging from 5 µm to approximately 58 µm. The studies were undertaken to employ this technology for the purpose of passive heat exchange intensification of heating surfaces in practical applications.

Download Full-text

J. C. Laser beam diameter for port wine stain treatment

Plastic & Reconstructive Surgery ◽

10.1097/00006534-199209000-00065 ◽

1992 ◽

Vol 90 (3) ◽

pp. 545

Author(s):

David B. Apfelberg ◽

r Keijze ◽

J. W Pickering ◽

Gemert van

Keyword(s):

Laser Beam ◽

Beam Diameter ◽

Port Wine Stain ◽

Port Wine ◽

Laser Beam Diameter

Download Full-text

Effects of laser beam diameter on electromagnetically induced transparency due to Zeeman coherences in Rb vapor

Physica Scripta ◽

10.1088/0031-8949/2013/t157/014019 ◽

2013 ◽

Vol T157 ◽

pp. 014019

Author(s):

S N Nikolić ◽

A J Krmpot ◽

N M Lučić ◽

B V Zlatković ◽

M Radonjić ◽

...

Keyword(s):

Laser Beam ◽

Electromagnetically Induced Transparency ◽

Beam Diameter ◽

Laser Beam Diameter ◽

Rb Vapor ◽

Induced Transparency

Download Full-text

Measurement of a Gaussian laser beam diameter through the direct inversion of knife-edge data

Applied Optics ◽

10.1364/ao.22.003406 ◽

1983 ◽

Vol 22 (21) ◽

pp. 3406 ◽

Cited By ~ 218

Author(s):

John M. Khosrofian ◽

Bruce A. Garetz

Keyword(s):

Laser Beam ◽

Beam Diameter ◽

Knife Edge ◽

Gaussian Laser Beam ◽

Laser Beam Diameter ◽

Direct Inversion

Download Full-text

Improving the Stability of Wood-Cutting Saws by Thermoplastic Action on the Distribution of Residual Stresses in the Blade

Lesnoy Zhurnal (Forestry Journal) ◽

10.37482/0536-1036-2020-6-172-181 ◽

2020 ◽

pp. 172-181

Author(s):

V.I. Melekhov ◽

◽

I.I. Solovev ◽

T.V. Tyurikova ◽

N.V. Ponomareva

Keyword(s):

Residual Stresses ◽

Thermal Exposure ◽

New Approach ◽

Circular Saw ◽

Compressive Stresses ◽

Transverse Bending ◽

The Creation ◽

The Stability ◽

Saw Blade ◽

Temperature Heating

The saw stability in operation defines the ability of the saw blade to resist the forces acting on it in the plane of greatest rigidity. The saw can work reliably only in case of maintaining stable balance, which is achieved through the creation of normalized residual stresses in certain zones of the saw blade by different methods. The stresses balance the forces of external influences. Compressive stresses are created in the central part of the blade to make the circular saw operational. These stresses compensate the forces of centrifugal acceleration, temperature heating of individual zones of the saw blade, external longitudinal and transverse bending forces arising in material processing. In practice, the creation of normalized stresses in the saw disk is traditionally carried out only by local mechanical contact action (forging, rolling) of the saw blade tool on the steel saw blade. It is proposed to form the stressed state of the disk by thermophysical action instead of the traditional mechanical processing of the saw blade. The thermophysical action involves the creation of normalized residual stresses in the saw blade by the concentrated thermal exposure to local differently directed narrow-band zones of straight or deflected shape, mainly radial or along concentric traces, controlling the process in real time. A new approach to the formation of residual stress fields in the saw blade by thermoplastic action enables to radically change the settingup procedure of the circular saw, ensuring its stability in operation.

Download Full-text