Laser Micro Welding of Dissimilar Material of Aluminum and Copper Alloys (original) (raw)
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Nd:YAG laser welding of aluminium alloys
1998
This thesis presents the development of laser welding of aluminium and describes what can be performed with modern Nd:YAG lasers in the wide range of commercial aluminium alloys available. Specific process and quality problems during aluminium welding have been approached and studied experimentally. In some cases analytical models have been developed in order to help explain the process and to support the conclusions. Paper one is a literature review comprising laser welding of low density structural materials, i.e. aluminium alloys, magnesium alloys, titanium alloys and polymers. The paper describes the properties of the different materials and explains how the properties influence the laser welding process and the weld results. For some of the materials laser welding was found to be the only successful fusion welding process. Paper two investigates Nd:YAG laser lap welding between sheets of two different coated aluminium alloys. Successful welds were produced using a certain gap w...
Influence of Surface State in Micro-Welding of Copper by Nd:YAG Laser
Applied Sciences
Laser welding of copper is characterized by low and unstable light absorption around 1000 nm wavelength. Combination of high thermal conductivity and low melting point makes it difficult to obtain good welding quality and leads to low energy utilization. To improve efficiency and welding quality, a technique to enhance process stability using 1064 nm wavelength Nd:YAG laser has been proposed, and absorption rate and molten volume in laser micro-welding were discussed. Since the surface state of specimen affects absorption phenomena, effects of surface shape and surface roughness were investigated. Absorption rate and molten volume were increased by creating appropriate concave holes and by controlled surface roughness. Stable micro-welding process with deep penetration and good surface quality was achieved for transitional processing condition between heat conduction and keyhole welding, by enhanced absorption rate.
A Study on Behavior of Materials Under The Influence of Laser Joining
IJRAME PUBLICATIONS, 2022
Laser welding will be an important welding process for different applications in aerospace , aircraft , automotive, electronics and other industries, due to its capabilities like minimum heat affected zone, welding of various thicknesses, adoptability to welding of various materials possessing widely varying physical properties like melting point, absorption, reflectivity etc. It utilizes laser source as a non contact heat generation technology to weld different materials so as to achieve welds of high quality narrow width and high penetration depths without the need of filler wires. It may be necessary to understand the effect of process parameters on the weldability of materials for successful welding. Laser welding popularly uses two types of lasers like CO2 and Nd:YAG (neodymium doped yttrium – aluminium – garnet) with different powers. Nd:YAG lasers are used to weld materials of different thicknesses involving powers upto 5 kW. Whereas, CO2 lasers are used for applications which involve higher powers upto 20 kW. Laser welding allows a direct transition from light energy into heat energy. This technique is involved with the process of laser - matter interaction in which various parameters such as pulse energy, pulse duration, spot size, welding speed, laser power, weld width, penetration depth, reflectivity, absorption coefficient, thermodynamic properties etc. are used for analysis. This paper presents a review of the different parameters including process as well as materials on the weldability of various materials like carbon steels, stainless steels, magnesium alloys, aluminium alloys, refractory materials such as vanadium, titanium, zirconium, tantalum etc. The selection of appropriate parameter for welding of specified material is discussed. The prominent weld defects common to the laser welding such as porosity, oxide inclusions, cracking, loss of alloying elements etc., are discussed as related to the microstructure as well as mechanical properties such as hardness, tensile strength and fatigue strength etc.
Journal of advanced joining processes, 2021
Effects of welding parameters on spot welded magnesium alloy joints have been investigated. With increasing welding time, the weld nugget diameter increased and the nugget microstructure became coarser. The joint strength (shear load at failure) of 2930-3050 N was obtained when welding time was longer than six cycles. Increasing welding currents from 15 to 23 kA resulted in an increase in the joint strength due to an increase in the nugget diameter. In the range of 1?5-4?5 kN electrode force, lowering the electrode force favours increasing the weld nugget diameter and improving the joint strength, but too low electrode force (1?5 kN) easily causes metal expulsion. The joints have two failure modes (interfacial failure and button pullout failure) under tensile shear loading conditions. For the button pullout failure, the crack initiates at cellular dendritic structure of nuggets and propagates along the cellular dendritic structure, heat affected zone (HAZ) and base metal in sequence.
Eastern-European Journal of Enterprise Technologies, 2022
This paper reports a study into features of the formation of structures of permanent butt joints of plates with a thickness of 1.5 mm made from the high-strength aluminum alloy 7075 of the Al-Zn-Mg-Cu system. Welding by melting these joints was performed using three techniques: laser, microplasma, and hybrid laser-microplasma. To implement the latter two, a compressed arc on a multipolar asymmetric current was used. The purpose of the research was to establish the tendency to the formation of characteristic defects and the possibility of their elimination. It has been determined that during laser welding a small (~5 %) volumetric fraction of defects in the form of pores is formed, residual welding deformations are minimized. There is a decrease in the hardness of the melted metal by 15 % with a simultaneous increase in the hardness of the heat-affected zone (HAZ) by 8...12 % relative to the base metal. In the melted metal, cavities up to 100 μm in size are formed, which are the center of the origin of hot cracks with a length of 25–30 μm. There are oxide inclusions in the root part of the seam. With microplasma welding, the volume fraction of defects of the melted metal in the form of pores with a size of 10...105 μm increases (up to 25 %). The hardness of the melted metal is reduced by 30 % with the hardness of the HAZ metal close to the base metal. In lasermicroplasma welding, the volumetric fraction of defects of the melted metal in the form of pores with a size of 15...25 μm is reduced to 5 %. The hardness of the melted metal is reduced by 15...20 % with the hardness of the HAZ metal close to the base metal. In the lower part of the melted metal, cavities of ~100 μm are formed. No microcracks were found in the seam metal. Analysis of the research results showed the advantage of the laser-microplasma technique. This method reduces the use of laser energy by 40...50 %, the lifetime of the welding pool (0.03...0.05 s) approaches laser welding, it eliminates the danger of burnout of alloying elements.
Metals, 2021
Dissimilar Ti–Al laser weldings are very interesting due to their difficulties in being processed because of the different physical properties of the alloys and the crack formations during cooling and solidification. In this study, the effect of laser offset and defocusing on microstructure, geometry and mechanical properties response of 2 mm thick dissimilar AA6061/Ti-6Al-4V laser welds was analyzed. Moreover, in order to reduce residual stresses, the joints were both heat-treated and mechanically treated by ultrasonic peening. The welds microstructure was found to be martensitic in the Ti-6Al-4V fusion zone, columnar dendritic in the AA6061 fusion zone and partially martensitic in the Ti-6Al-4V heat-affected zone. Intermetallic compounds based on the Al–Ti system were detected at the AA6061/Ti-6Al-4V interface and in the aluminum fusion zone. Both negative defocusing and higher laser offset improved the tensile performance of the welds, mainly by reducing the amount of brittle int...
International journal of engineering & technology, 2016
The demand for high performance materials particularly in aviation and automobile industries gradually increases, CO 2 and Nd: YAG lasers are becoming most popular in processing these advanced materials. In this context, one of the most important process is joining by welding. It has been a constant endeavour by researchers to explore various methods and techniques to enhance the process efficiency of autogenous Nd: YAG laser welding of various materials i.e. without any filler materials. In this work, we present a comprehensive review of major research findings for the last decades or so, obtained by researchers about the effect of process parameters on autogenous laser beam welding (LBW) process performance. Main objective of such experimental research was to improve laser weld quality such as tensile strength, weld micro structure, heat affected zone (HAZ), weld penetration etc. In this paper, discussions are also made about different parameter optimisation techniques, design of experiments (DOE), modelling and simulation techniques, adopted by different researchers to achieve optimum weld quality. This review tries to bring out a foresight for direction of further research needed in this field.
Laser micro-welding of aluminum alloys: experimental studies and numerical modeling
The International Journal of Advanced Manufacturing Technology, 2010
Experimental and numerical studies were conducted on the effects of the laser beam pulse shaping in the time domain on the quality of the welding seam in laser micro-welded AlMg3 with a thickness of 0.2 mm and 1 mm thick AlMg4.5 Mg foils, respectively. The pulse shaping was realized by a time sequence of three different rectangular pulses with different duration and power level. The first pulse was used to pre-heat the sample, welding occurred with the second pulse and the third pulse controlled the melt pool behavior. The power level and the duration of the single pulses were varied systematically and the resulting microstructure was analyzed by scanning electron microscope. The experiments were accompanied by numerical simulations based on a finite volume model which considers the transient heat flow, melt convection and the evolution of a gas capillary during the deep penetration welding process.
An investigation on capability of hybrid Nd:YAG laser-TIG welding technology for AA2198 Al-Li alloy
Optics and Lasers in Engineering, 2017
This paper surveys the capability of the hybrid laser-arc welding in comparison with lone laser welding for AA2198 aluminum alloy experimentally. In the present research, a continuous Nd:YAG laser with a maximum power of 2000 W and a 350 A electric arc were used as two combined welding heat sources. In addition to the lone laser welding experiments, two strategies were examined for hybrid welding; the first one was low laser power (100 W) accompanied by high arc energy, and the second one was high laser power (2000 W) with low arc energy. Welding speed and arc current varied in the experiments. The influence of heat input on weld pool geometry was surveyed. The macrosection, microhardness profile and microstructure of the welded joints were studied and compared. The results indicated that in lone laser welding, conduction mode occurred and keyhole was not formed even in low welding speeds and thus the penetration depth was so low. It was also found that the second approach (high laser power accompanied with low arc energy) is superior to the first one (low laser power accompanied with high arc energy) in hybrid laser-arc welding of Al2198, since lower heat input was needed for full penetration weld and as a result a smaller HAZ was created.