scholarly journals Mechanical Properties of Fibre Laser Welded AZ31B Sheets and their Dependence on the Spot-Size

2015 ◽  
Vol 828-829 ◽  
pp. 298-304
Author(s):  
Stefan Riekehr ◽  
Riccardo Ravasi ◽  
Josephin Enz ◽  
Volker Ventzke ◽  
Nikolai Kashaev
Keyword(s):  
Laser Beam ◽  
Laser System ◽  
Base Material ◽  
Spot Size ◽  
Fibre Laser ◽  
Beam Power ◽  
Spot Diameter ◽  
Laser Beam Power ◽  
Focus Spot ◽  
Weld Area

In the present work the mechanical behaviour of laser beam welded AZ31B alloy was studied, by changing systematically the spot size of the used fibre laser system between 200 µm and 1000 µm at different power levels between 2 kW and 8 kW. Maximum welding velocities with respect to imperfections were determined. The characterization of the obtained welds - in terms of Vickers hardness, UTS, Af and weld width, resp. weld area - was correlated with the micro-texture in dependence of the different Focus Spot Diameters and Laser Beam Power levels as well as the resulting cooling rates. Highest UTS of 94% of the base material was achieved with 200 µm Focus Spot Diameter and Laser Beam Power of 4 kW at welding velocity of 100 mm/s. By increasing the Focus Spot Diameter to 600 µm, the tensile strength was reduced to 86 % of the actual strength of the base material.

Fiber Laser Beam Welding of Ti-6242 - Effect of Processing Parameters on Microstructural and Mechanical Properties

2016 ◽  
Vol 879 ◽  
pp. 903-908 ◽  
Author(s):  
Nikolai Kashaev ◽  
Dmitry Pugachev ◽  
Stefan Riekehr ◽  
Volker Ventzke
Keyword(s):  
Mechanical Properties ◽  
Laser Beam ◽  
Fiber Laser ◽  
Laser Beam Welding ◽  
Base Material ◽  
Butt Joint ◽  
Beam Power ◽  
Focus Position ◽  
Laser Beam Power ◽  
Advance Speed

The present work investigates the effects of laser beam power, focus position and advance speed on the geometry, microstructure and mechanical properties of fiber laser beam welded Ti-6Al-2Sn-4Zr-2Mo (denoted as Ti-6242) butt joints used for high temperature applications. Detailed microstructural and mechanical studies were performed on welds produced using optimized parameters (a laser beam power of 5 kW, a focus position of 0.0 mm and an advance speed of 6.2 m/min). The Ti-6242 base material is characterized by a globular (α+β) microstructure. The heat input during laser beam welding led to the formation of a martensitic α’-phase fusion zone. The heat affected zone consisted of globular grains and acicular crystallites. These local transformations were connected with a change in the micro-texture, average grain size and β-phase content. Furthermore, the microhardness increased from 330 HV 0.3 to 450 HV 0.3 due to the martensitic transformation. The mechanical behavior of the laser beam welded Ti-6242 butt joint loaded in tension was determined by the properties of the Ti-6242 base material. The local increase in hardness provided a shielding effect that protected the Ti-6242 butt joint against mechanical damage.

EXPERIMENTAL STUDIES ON THE MICROSTRUCTURE AND HARDNESS OF LASER TRANSFORMATION HARDENING OF LOW ALLOY STEEL

2012 ◽  
Vol 36 (3) ◽  
pp. 241-258 ◽  
Author(s):  
Purushothaman Dinesh Babu ◽  
Gengusamynaidu Buvanashekaran ◽  
Karupuudaiyar R. Balasubramanian
Keyword(s):  
Laser Beam ◽  
Laser System ◽  
Experimental Studies ◽  
Surface Hardness ◽  
Base Material ◽  
Optical Microscope ◽  
Laser Hardening ◽  
Beam Power ◽  
Work Piece ◽  
Laser Transformation Hardening

An experimental investigation with Nd:YAG laser system was carried out to study the effects of laser hardening process parameters on the microstructure and hardness during laser hardening of EN25 steel. The laser beam is allowed to scan on the surface of the work piece by varying the laser beam power (750–1250 W) and travel speed (500–1000 mm/min) of the work table. The microstructural features of the laser hardened EN25 steel were analysed using optical microscope. The microstructure of the surface layer was found to consist of plate martensite. A substantial increase in surface hardness was achieved, by a factor of 2 times the base material hardness.

Alloying of Ohmic Contacts to n-Type 4H-SiC via Laser Irradiation

2013 ◽  
Vol 740-742 ◽  
pp. 773-776 ◽  
Author(s):  
A. Hürner ◽  
T. Schlegl ◽  
B. Adelmann ◽  
H. Mitlehner ◽  
R. Hellmann ◽  
...  
Keyword(s):  
Laser Beam ◽  
Contact Resistance ◽  
Ohmic Contacts ◽  
Continuous Wave ◽  
Laser System ◽  
Beam Power ◽  
Voltage Measurement ◽  
Processing Times ◽  
Laser Beam Power ◽  
Beam Propagation Factor

In this study, we present the results of alloying nickel as ohmic contact material to n-type 4H-SiC via a continuous wave fiber laser with different laser beam powers and processing times. The laser system exhibits an emitting wavelength of 1070 nm and a beam propagation factor M2 smaller than 1.1. Contact resistance was determined by current-voltage measurement using the two-terminal contact resistance method. The results indicate that a laser beam power of at least 100 W is mandatory to initialize contact silicidation. Although the contact resistance is improvable by longer processing times, our experiments outline the much higher impact of laser beam power to contact silicidation compared with processing time. For laser beam powers of 300 W and processing times of 0.5 s a contact resistance of 6.5 , comparable to contacts alloyed in a lamp heated furnace at 910 °C for 2 min with a contact resistance of 10.3 , was achieved.

Laser beam guiding in partially stripped magnetized quantum plasma

Laser Physics ◽  
2021 ◽  
Vol 32 (1) ◽  
pp. 016002
Author(s):  
Punit Kumar ◽  
Nisha Singh Rathore
Keyword(s):  
Laser Beam ◽  
Spot Size ◽  
Quantum Plasma ◽  
Beam Power ◽  
Linear Wave ◽  
Linear Wave Equation ◽  
Quantum Hydrodynamic Model ◽  
Bohm Potential ◽  
Expansion Technique ◽  
Linearly Polarized

Abstract Relativistic and ponderomotive nonlinearities arising by the passage of a linearly polarized laser beam through a partially stripped magnetized quantum plasma are analyzed. The interaction formalism has been developed using the recently developed quantum hydrodynamic model. The effects associated with the Fermi pressure, quantum Bohm potential and electron spin have been incorporated. A nonparaxial, non-linear wave equation has been obtained by the use of source dependent expansion technique and spot size has been evaluated. The nonlinear relativistic self-focusing tends to focus the beam while the ponderomotive nonlinearity tends to defocus. The effect of magnetization and quantum effects on the spot size and the beam power have been studied.

scholarly journals The influence of laser re-melting on microstructure and hardness of gas-nitrided steel

2016 ◽  
Vol 36 (1) ◽  
pp. 18-22 ◽  
Author(s):  
Dominika Panfil ◽  
Piotr Wach ◽  
Michał Kulka ◽  
Jerzy Michalski
Keyword(s):  
Laser Beam ◽  
Laser Treatment ◽  
Diffusion Zone ◽  
Nitrided Layer ◽  
Nitriding Process ◽  
Beam Power ◽  
Gas Nitriding ◽  
Nitrided Steel ◽  
Laser Beam Power ◽  
And Diffusion

Abstract In this paper, modification of nitrided layer by laser re-melting was presented. The nitriding process has many advantageous properties. Controlled gas nitriding was carried out on 42CrMo4 steel. As a consequence of this process, ε+γ’ compound zone and diffusion zone were produced at the surface. Next, the nitrided layer was laser remelted using TRUMPF TLF 2600 Turbo CO2 laser. Laser tracks were arranged as single tracks with the use of various laser beam powers (P), ranging from 0.39 to 1.04 kW. The effects of laser beam power on the microstructure, dimensions of laser tracks and hardness profiles were analyzed. Laser treatment caused the decomposition of continuous compound zone at the surface and an increase in hardness of previously nitrided layer because of the appearance of martensite in re-melted and heat-affected zones

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