JLA Vol:25 Iss:5 (Heat transfer and fluid flow in additive manufacturing)

Authors:
A. Raghavan
H. L. Wei
T. A. Palmer
T. DebRoy
Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802

In laser-based direct energy deposition additive manufacturing, process control can be achieved through a closed loop control system in which thermal sensing of the melt pool surface is used to adjust laser processing parameters to maintain a constant surface geometry. Although this process control technique takes advantage of important in-process information, the conclusions drawn about the final solidification structure and mechanical properties of the deposited material are li...

JLA Vol:25 Iss:5 (Investigation into the effects of process parameters on bending angle in the laser bending of tailor machined blanks based on a statistical analysis)

Authors:
Mehdi Safari
Mahmoud Farzin
Abbas Ghaei
Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran

In this paper, the effects of process parameters on bending angle in laser bending of tailor machined blanks are investigated experimentally. The Taguchi experimental design method is employed to study various parameters, which significantly affect the bending angle in the laser bending of tailor machined blanks. The start point of scan path, irradiating method, laser output power, beam diameter, and number of radiation passes are considered in the evaluations. A L₁₈(2¹×3⁴) Ta...

JLA Vol:25 Iss:5 (Laser remote-fusion cutting with solid-state lasers)

Authors:
A. Wagner
M. Lu¨tke
A. Wetzig
Fraunhofer Institute for Material and Beam Technology IWS, Winterbergstraße 28, 01277 Dresden, Germany

L. M. Eng
Institute of Applied Photophysics, TU Dresden, George-Ba¨hr-Straße 1, 01062 Dresden, Germany

A laser remote cutting process is analyzed, which differs significantly from established laser cutting processes. On the one hand, no cutting gas is needed and a high working distance is realized. On the other hand—in opposite to conventional laser remote cutting—sheets of metal with thicknesses above 1 mm can be cut in one step. Examinations were carried out at the...

JLA Vol:25 Iss:5 (Laser-induced thermoelectric voltage in La_0.9Pr_0.1MnO₃ thin films)

Authors:
Lisheng Zhang
Qianqian Hua
Yan Fang
Beijing Key Laboratory for Nano-Photonics and Nano-Structure, Capital Normal University, Beijing 100048, People's Republic of China

The laser-induced thermoelectric voltage (LITV) was observed in La_0.9Pr_0.1MnO₃ thin films grown on the vicinal cut LaAlO₃ substrate by pulsed laser deposition for the first time. The detected signals were demonstrated to be originated from the anisotropic Seebeck effect. The largest peak value of the voltage is about 2.4 V, the full width at half-maximum of the temporal voltage peak and the rising time are 300–500 and 40–50 n...

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:25 Iss:5 (Review study on remote laser welding with fiber lasers)

Authors:
Jinhong Lu
ABB Electrical Machines Ltd, Shanghai, China, 200245

Veli Kujanpa¨a¨
VTT Technical Research Centre of Finland, Lappeenranta, Finland, 53850

The appearance of the high-power fiber laser with brilliant beam quality enables a rapid development of remote laser welding (RLW). In this paper, a theoretical study of remote laser welding has been reviewed. As a promising technology, the RLW offers an increased flexibility, high operational speed, and reduced cycle time to process a wide range of workpieces. This study presents the feasibility and typical characteristics of RLW with high-power fiber lasers. Meanwhile, the influence of process pa...

JLA Vol:25 Iss:5 (Stoichiometric 6H-SiC thin films deposited at low substrate temperature by laser ablation)

Authors:
J. G. Quin˜ones-Galva´n
Physics Department, CINVESTAV-IPN, Apdo. Postal 14-740 Me´xico, D.F. 07360, Mexico

J. S. Arias-Cero´n
CICATA-IPN, Unidad Legaria, Me´xico D.F. 11500, Mexico

F. de Moure-Flores
Facultad de Qui´mica, Materiales, Universidad Auto´noma de Quere´taro, Quere´taro 76010, Mexico

A. Herna´ndez-Herna´ndez
A. Guille´n-Cervantes
J. Santoyo-Salazar
J. G. Mendoza-Alvarez
M. Mele´ndez-Lira
Physics Department, CINVESTAV-IPN, Apdo. Postal 14-740 Me´xico, D. F. 07360, Mexico


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JLA Vol:25 Iss:5 (Use of track/layer morphology to develop functional parts by selective laser melting)

Authors:
I. Yadroitsev
Ph. Bertrand
Universite´ de Lyon, Ecole Nationale d'Inge´nieurs de Saint-Etienne (ENISE), DIPI Laboratory, 58 rue Jean Parot, 42023 Saint-Etienne Cedex 2, France

G. Antonenkova
S. Grigoriev
Moscow State University of Technology “STANKIN”; Vadkovsky per., 1, 127994 Moscow, Russia

I. Smurov
Universite´ de Lyon, Ecole Nationale d'Inge´nieurs de Saint-Etienne (ENISE), DIPI Laboratory, 58 rue Jean Parot, 42023 Saint-Etienne Cedex 2, France

Selective laser melting (SLM) is a powder-based additive manufacturing capable to produce parts layer-by-layer from...

JLA Vol:26 Iss:1 (Effect of material properties on the laser welding mode limits)

Authors:
Eurico Assuncao
Stewart Williams
Welding Engineering and Laser Processing Centre, Cranfield University MK43 0AL, United Kingdom

Aluminum, mild steel, and stainless steel have very dissimilar thermal properties. This study focuses on the effect of power density on the laser welding conduction mode limit in these three materials. The objective is to evaluate how these different materials will behave in conduction mode and in keyhole mode and also to understand how the thermal properties of the materials will influence the transition between the different welding modes. A comparison between the penetration depth and the melted area for the different materials under ...

JLA Vol:26 Iss:1 (Evolution of nano-ripples on stainless steel irradiated by picosecond laser pulses)

Authors:
Bin Liu
Wenjun Wang
Gedong Jiang
Xuesong Mei
Kedian Wang
Jiuhong Wang
Zibao Wang
State Key Laboratory for Manufacturing System Engineering, Xi'an Jiaotong University, Xi'an 710054, China

The characteristics of laser-induced periodic surface structures are investigated after laser irradiation with a pulse duration (10 ps) under a certain laser fluence (0.27 J/cm²) and pulse number (N = 50–2000). In the experiments, at the lowest number of pulses, ultrafine ripples are observed with sub-200-nm spatial periods and an orientation parallel to laser polarization ...