Numerical analysis of the effects of non-conventional laser beam geometries during laser melting of metallic materials

Safdar, Shakeel; Li, Lin; Sheikh, M. A.

doi:10.1088/0022-3727/40/2/039

Cited by 37 publications

(26 citation statements)

References 26 publications

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“…The laser melting of ceramics was studied by Li et al [7], who showed that the model incorporating the volumetric heating source is more accurate in the prediction of the melting process than the than the surface heating source model. The influence of the laser beam geometry on the laser transformation hardening of steel was investigated by Safdar et al [8], who indicated that the triangular beam geometry produced the best thermal history to achieve improved transformation hardening and highest hardness without sacrificing the processing rate and hardening depths.…”

Section: Introductionmentioning

confidence: 99%

Laser repetitive pulse heating and melt pool formation at the surface

2011

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In this paper, laser repetitive pulse heating of steel surface is conducted to predict temperature and melt pool geometry in the irradiated region. The enthalpy porosity method is incorporated to account for the phase change in the irradiated surface. The flow field in the melt pool is simulated after considering the Marangoni effect. To examine the influence of the laser pulse intensity distribution on the formation and flow field in the melt pool, the laser pulse intensity parameter (β) is introduced in the analysis. An experiment is conducted to compare the melt pool geometry predicted from the simulation and that obtained from the experiment. The melt pool size is significantly affected by the intensity parameter (i.e., the melt pool is too shallow for high-intensity parameters). The predicted melt pool geometry is in agreement with the experimental results.

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Section: Introductionmentioning

confidence: 99%

Laser repetitive pulse heating and melt pool formation at the surface

2011

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“…Hence, the best FPP search amounts to finding the beam characteristics that provide an optimal (not maximal) load of the laser power into the laser-matter interaction region. 40 The effect of the LID shape on the performance of laser technology processes has been repeatedly confirmed in experiments. Some papers directly attributed the cutting quality to fiber [2][3][4][5]18,35 and conventional 41,42 laser beam quality.…”

Section: Laser Beam Shape Position and Distortionmentioning

confidence: 77%

Gas-assisted laser cutting of medium-section metals using spherically aberrated beams

Yurevich

Grimm

Polyakov³

et al. 2015

Opt. Eng

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Abstract. We analyzed the effects of the focal point aberrational offset in optical transport systems for highpower lasers. Transverse and near-axial laser intensity distribution transformations in the presence of both positive and negative spherical aberrations were numerically calculated and experimentally demonstrated for different strengths. We show that spherical aberration yields considerable asymmetry of the focused beam's caustic. Several optical transport systems with identical optical parameters (excluding the noncorrected axial beam spherical aberration) were designed. We examined the effects of the laser intensity profiles produced by these systems on the quality of oxygen-assisted laser cutting of medium-section mild steel. We show that high-quality cuts can be obtained for different shapes of laser intensity distribution. However, the greater the refocusing magnitude introduced by the spherical aberration correction, the more precisely the focal point position must be maintained during the laser cutting process. © The Authors. Published by SPIE under a Creative Commons 1 Introduction Laser cutting of metals and alloys is one of the most commercially valuable laser technology processes. Originating from basic research on laser-matter interaction, 1 the field has significantly developed, now offering a large arsenal of state-of-the-art techniques.2-5 Omitting the energy and resource efficiency issues, 6 the performance of laser cutting can be captured by only two output parameters. These are the cutting speed and kerf quality. Thus, laser cutting optimization reduces to achieving the maximal cutting speed with the best kerf quality. As far as the material separation is concerned, 7 the speed can be dramatically increased. On the other hand, the cutting quality depends on many parameters. The most important and frequently discussed are the kerf geometry (accuracy, width, and taper), the surface quality (cut-edge roughness, striations morphology, and dross and burr inclusions), and the mechanical and metallurgical properties (hardness and strength, heat-affected zone, and oxide layer). 8 The number of parameters dramatically affecting the cutting quality ranges from 25 9 to 75. 4,5 These are nearly evenly divided between the workpiece properties, assist gas parameters, laser machine, and laser beam characteristics. Input-output parameters relationships are mostly nonlinear and exhibit strong interdependence. In this regard, maximal precision is provided by the studies that focus on only one input-output parameter pair. Yet, this "one parameter at one time" approach does not provide complete information on the process as a whole.

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“…The last one was the method of Area Sector Approach. The geometry of the heat treated sample was the main factor in selecting the method of modeling [15] [16]. The second method was efficient only if the geometry was not intricate, and the third was applicable when the movement was simple.…”

Section: Introductionmentioning

confidence: 99%

Hardness Profile Prediction for a 4340 Steel Spline Shaft Heat Treated by Laser Using a 3D Modeling and Experimental Validation

Hadhri¹,

Ouafi²,

Barka³

2016

MSCE

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Laser surface transformation hardening becomes one of the most effective processes used to improve wear and fatigue resistance of mechanical parts. In this process, the material physicochemical properties and the heating system parameters have significant effects on the characteristics of the hardened surface. To appropriately exploit the benefits presented by the laser surface hardening, it is necessary to develop a comprehensive strategy to control the process variables in order to produce desired hardened surface attributes without being forced to use the traditional and fastidious trial and error procedures. The paper presents a study of hardness profile predictive modeling and experimental validation for spline shafts using a 3D model. The proposed approach is based on thermal and metallurgical simulations, experimental investigations and statistical analysis to build the prediction model. The simulation of the hardening process is carried out using 3D finite element model on commercial software. The model is used to estimate the temperature distribution and the hardness profile attributes for various hardening parameters, such as laser power, shaft rotation speed and scanning speed. The experimental calibration and validation of the model are performed on a 3 kW Nd:Yag laser system using a structured experimental design and confirmed statistical analysis tools. The results reveal that the model can provide not only a consistent and accurate prediction of temperature distribution and hardness profile characteristics under variable hardening parameters and conditions but also a comprehensive and quantitative analysis of process parameters effects. The modelling results show a great concordance between predicted and measured values for the dimensions of hardened zones.

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Numerical analysis of the effects of non-conventional laser beam geometries during laser melting of metallic materials

Cited by 37 publications

References 26 publications

Laser repetitive pulse heating and melt pool formation at the surface

Laser repetitive pulse heating and melt pool formation at the surface

Gas-assisted laser cutting of medium-section metals using spherically aberrated beams

Hardness Profile Prediction for a 4340 Steel Spline Shaft Heat Treated by Laser Using a 3D Modeling and Experimental Validation

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