Influence of Temperature and Wavelength on Optical Behavior of Copper Alloys

Quantitative measured values for absorption of copper and its alloys are jet unknown in the temperature range between 30 °C and 500 °C which has to be passed before material melts in the initial phase of laser beam welding. Thus this paper investigates temperature and wavelength dependent absorption for VIS and IR wavelengths. For this purpose specimens of copper and copper alloys are heated up and reflected laser light from the surface is measured by using an Ulbricht sphere in combination with a photodiode. During welding processes inert gases are in use to reduce oxidation. Hence the influence of shielding gases on the absorption will also be taken into account during the heating process of the specimens. Consequently this paper provides results for the temperature dependent absorption of copper and copper alloys for different wavelengths at atmospheric conditions and argon shielding.

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Influence of Surface Structured Filler Wires on Laser Beam Welding of Copper Alloys

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.805.171 ◽

2015 ◽

Vol 805 ◽

pp. 171-179 ◽

Cited By ~ 1

Author(s):

Vincent Mann ◽

Fabian Gärtner ◽

Florian Hugger ◽

Konstantin Hofmann ◽

Felix Tenner ◽

...

Keyword(s):

Energy Efficiency ◽

Laser Beam ◽

Weld Seam ◽

Copper Alloys ◽

Laser Beam Welding ◽

Welding Process ◽

Industrial Applications ◽

Additional Amount ◽

Infrared Wavelengths ◽

Welding Processes

Compared to steel, the required amount of energy for conventional welding of copper is higher, due to its higher thermal conductivity. This problem is mainly solved by preheating the work pieces or welding processes with high intensities such as laser beam welding. As the absorption of copper for infrared wavelengths, which are commonly used in industrial applications today, is typically low, the energy efficiency of the laser welding process is low. Besides this, if filler wires are used in order to increase the bridgeable width of joining gaps, the energy consumption of the process is further increased due to the additional amount of energy required to melt the filler material.As roughened surfaces of copper parts are known to increase absorption and consequently energy efficiency of laser beam welding without filler wires, this paper investigates the influence of surface structured filler wires on laser beam welding of copper alloys. Thus, the correlation between knurling geometries, absorption, molten volume and the welding result is investigated. For this reason, the welding result is evaluated by means of geometrical, electrical and mechanical weld seam properties e.g. seam width, weld reinforcement, area of cross-section, electrical resistance, tensile strength and strain.

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Laser diagnostic for measuring the temperature dependent absorption coefficient of laser thruster gas mixtures

10.2514/6.1980-1372 ◽

1980 ◽

Author(s):

M. FOWLER

Keyword(s):

Absorption Coefficient ◽

Gas Mixtures ◽

Temperature Dependent ◽

Laser Diagnostic ◽

Dependent Absorption

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Enabling Rewards for Reinforcement Learning in Laser Beam Welding processes through Deep Learning

2020 19th IEEE International Conference on Machine Learning and Applications (ICMLA) ◽

10.1109/icmla51294.2020.00221 ◽

2020 ◽

Author(s):

Markus Schmitz ◽

Florian Pinsker ◽

Alexander Ruhri ◽

Beibei Jiang ◽

Georgij Safronov

Keyword(s):

Deep Learning ◽

Reinforcement Learning ◽

Laser Beam ◽

Laser Beam Welding ◽

Welding Processes

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Development of laser welding of high strength aluminium alloy 2024-T4 with controlled thermal cycle

MATEC Web of Conferences ◽

10.1051/matecconf/202032608005 ◽

2020 ◽

Vol 326 ◽

pp. 08005

Author(s):

Mete Demirorer ◽

Wojciech Suder ◽

Supriyo Ganguly ◽

Simon Hogg ◽

Hassam Naeem

Keyword(s):

Laser Beam ◽

Laser Welding ◽

Heat Input ◽

Thermal Cycle ◽

Laser Beam Welding ◽

Base Material ◽

High Strength ◽

Cooling Rates ◽

Aa 2024 ◽

Welding Processes

An innovative process design, to avoid thermal degradation during autogenous fusion welding of high strength AA 2024-T4 alloy, based on laser beam welding, is being developed. A series of instrumented laser welds in 2 mm thick AA 2024-T4 alloys were made with different processing conditions resulting in different thermal profiles and cooling rates. The welds were examined under SEM, TEM and LOM, and subjected to micro-hardness examination. This allowed us to understand the influence of cooling rate, peak temperature, and thermal cycle on the growth of precipitates, and related degradation in the weld and heat affected area, evident as softening. Although laser beam welding allows significant reduction of heat input, and higher cooling rates, as compared to other high heat input welding processes, this was found insufficient to completely supress coarsening of precipitate in HAZ. To understand the required range of thermal cycles, additional dilatometry tests were carried out using the same base material to understand the time-temperature relationship of precipitate formation. The results were used to design a novel laser welding process with enhanced cooling, such as with copper backing bar and cryogenic cooling.

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Determination of Heat Input in Tungsten Inert Gas and Laser Welding of Type Optim 960 QC Structural Steel Using Adams’ Equation for 2-D Heat Distribution

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.750.45 ◽

2017 ◽

Vol 750 ◽

pp. 45-52

Author(s):

Sveto Cvetkovski

Keyword(s):

Laser Welding ◽

Heat Input ◽

Arc Welding ◽

Research Work ◽

Laser Beam Welding ◽

Peak Temperature ◽

Efficiency Coefficient ◽

Zone Recrystallization ◽

Welding Processes

The heat input during conventional arc welding processes can be readily calculated knowing the power taken from the power source. The efficiency coefficient can be taken from the appropriate literature standards. Here, the intention of the performed research work was to develop a procedure for determination of heat input in arc and laser welding processes implementing Adams equation - modified Rykalin equation for two dimensional heat distributions (2-D). To realize this idea, it is necessary to determine two characteristic temperatures points in the HAZ with known peak temperature, and to determine distance between them. Implementing measured values for distance in Adams’ equation, heat input in arc welding can be directly determined in arc welded joints.In laser beam welding, the absorption of the beam in the metal is not known, so that the welding heat input cannot be calculated directly, and direct implementation of Adam’s equation is not possible i.e. absorption coefficient has to be determined first, and after that calculation of heat input is possible.The peak temperatures corresponding to specific microstructures can be obtained by performing welding simulation, by the Gleeble 1500 simulator in our case. As one of the peak temperatures, the melting temperature can be used corresponding to the fusion line, so that at least one characteristic peak temperature such as coarse grain zone, fine grin zone, intercritical zone, recrystallization, has to be determined by the simulation.Performed research showed that obtained values for heat input using Adam’s equation correspond pretty well with standard equation for heat input in arc welding.

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