Laser Welding

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.

Weld quality mainly depends on the weld bead geometry and mechanical-metallurgical characteristics of the welded joint which has a direct relationship with the type of welding process being used and its input process parameters i.e. welding current, arc voltage, travel speed etc. In the present study, determination of tungsten inert gas (TIG) welding input parameters for achieving maximum tensile strength of 316L austenitic stainless steel is investigated. Box-Behnken design of response surface methodology has been employed to formulate the experimental plan to identify the effect of process parameters on tensile strength. Square butt joint configuration has been made using three factors - three levels of welding input parameters. Joint strength has been evaluated by notch tensile strength (NTS) and Unnotch tensile strength (UTS) method and correlated with microstructure and micro hardness of the weld. The results indicate that gas flow rate has greater influence on both NTS and UTS...

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On behalf of the Organizing Committee, we extend a warm and cordial welcome to you to be part of 22th Symposium on High Power Laser Systems and Applications, held conjointly with eminent researchers and scholars from all around the globe during October 9 - 12, 2018 in the amazing venue of Villa Mondragone, Frascati, near Rome, Italy.
You can be a part of this event by participating as a speaker by giving oral presentation or you can give poster presentation in your area of expertise.
Selected papers will be published in the Proceedings published by SPIE.
The conference will also provide delegates with the opportunity to consolidate their knowledge and understanding of the latest scientific advancements on laser systems and their applications.

Welcome in Frascati!

A model based on a double-ellipsoidal volume heat source to simulate the gas metal arc welding (GMAW) heat input and a cylindrical volume heat source to simulate the laser beam heat input was developed to predict the temperature field and thermally induced residual stress in the hybrid laser–gas metal arc (GMA) welding process. Numerical simulation shows that higher residual stress is distributed in the weld bead and surrounding heat-affected zone (HAZ). Effects of the welding speed on the isotherms and residual stress of the welded joint are also studied. It is found that an increase in welding speed can reduce the residual stress concentration in the as-weld specimen. A series of experiments has been performed to verify the developed thermo-mechanical finite element model (FEM), and a qualitative agreement of residual stress distribution and weld geometrical size is shown to exist.

Laser welding is a common technique in the automotive industry. For economic reasons, it is of great importance to detect the defects that can appear. The CO2 penetration laser welding process is characterized by the formation of an electron-free plasma whose radiation can be measured to detect the defects. This paper presents two different approaches to defect detection. The first is based on the correlation between the power spectrum of a photodiode-generated signal and the defects. The second approach is based on the plasma electronic temperature, which is correlated to the presence of defects. Results obtained in an industrial facility under production conditions are presented.

Joining steel plates and aluminum plates by means of using Fe/Al structural (Triclad) transition joints has been well-received in the shipbuilding industry, but is rarely applied in other industries. In this work, 12.7 mm thick plates of advanced high-strength steel and AA 6061 alloy were successfully joined by using hybrid laser-arc welding with the help of Triclad transition joints. The parameters were optimized for welding dissimilar steels (A516 to advanced high-strength steel) and welding dissimilar aluminum alloys (AA 5456 to AA 6061). The optimization controlled the total heat input and kept the Al/Fe interface
of the Triclad transition joint below the maximum allowable temperature of 315.56 C in order to minimize the growth of brittle intermetallic phases and retain the mechanical properties of the Triclad transition joint. A finite element model was developed to study the temperature evolution at the Triclad interface and the heat distribution along with the welded structure. A ‘‘4:1’’ ratio was used between the width
of the Triclad transition joint and the thickness of the webs. This ratio improved the load-bearing property of the Triclad transition joint and compensated for the microcracks and brittle Al-rich intermetallic
phases observed at the Triclad interface. Tensile strength of 220 MPa was achieved at the welded structure. The fracture occurred at the heat-affected zone of the AA 5456-to-AA 6061 weld.

In this paper, simultaneous laser transmission welding process is systematically investigated via process modeling, using an FEM and RSM combined approach. The objective of the present research is to study the effects of process parameters on the temperature field and weld bead dimensions. The thermal field is simulated by solving a three dimensional transient heat diffusion equation with temperature dependent material properties using the ANSYS® multi-physics. Response surface methodology is then applied for developing mathematical models based on simulation results. The second order equations developed by RSM can predict the values of the responses with significant accuracy. The effect of parameters and their interactions on the responses are studied using the developed response surface models. The mathematical models are further used in search of the optimal process window for obtaining an acceptable weld. The graphical optimization results into a couple of overlay contours plots, which allow quick visual inspection of the area of feasible response values in the factor space to choose the favorable welding parameter combination.►FEM along with RSM is employed to study the simultaneous laser transmission welding process. ► The numerical simulation is performed using the commercial FE package ANSYS®. ► The temperature distribution and shape and size of the molten pool are computed. ► RSM is used to analyze the responses and to determine the mathematical models with best fits. ► The effect of parameters and their interactions on the responses are studied and discussed.

Laser technology for material processing, which was appeared about three decades ago, is currently experiencing the peak of its development and popularity. Modern fiber laser technologies are rapidly being introduced into industrial production and advertising business, often replacing traditional methods of material processing. The focused laser beam of adjustable power turned out to be an ideal "working tool" for the creators of new equipment. The laser system for cutting and marking, welding and surfacing, as a material processing tool, works quickly and does not wear out, it is economical, highly accurate, and its impact is easy to control and manage.

Welding is the most important joining technology, which is well expressed by the appearance of a very large number of process-variations corresponding developed filler and auxiliary materials, and in a wide range of corresponding automation.
These are a combination of a welding base upon which the designer, technologist and manager can also build. To make this "construction" well substantiated, the present book intends to contribute by a systematic and concise overview of the units listed. The aim is a theoretical and practical summary which may support and
expand the background knowledge of those in contact with welding. It wishes to provide information in a compact and encyclopedic form to the readers of the welding part-area – the welding and allied processes, respectively the possibilities of mechanization – which simply be described as a technical background.
From a substantive point of view this book regards as allied technologies of welding the following:
- brazing and other joining technologies, such as the bonding and mechanical bonding;
- preparation of the workpiece (eg. cutting, chamfering) by thermal and other (erosion, shearing, chipping) form of cutting as a forming technology;
- and often the after bandage surface treatment, as a technology modifying the structure of matter, and thus adjusting quality.
This book presents the standardized marking systems and classification of welding and allied processes. This is the internationally accepted numerical sort of “common language" that all professionals understand independently of their ethnic background, and it represents the solid-script of reference in various fields.
Due to their characteristics of application, flexibly programmable industrial robots cooperating with peripheries are distinguished within the mechanization toolbar.
Their use increases productivity, reduces the cycle time of manufacturing, improves quality and reproduction, increases the flexibility of the production system, makes it possible to reduce monotonous and heavy physical work and substitutes human activity in areas harmful to health. The mechanization of welding conditions is usually determined by application of device-parts, as well as simple and complex devices, and auxiliary plants. These may also reduce welders physical wear and the welding side-time. The book also deals with these sub-divisions of welding.
A hegesztés a legfontosabb kötőtechnológia, amit jól kifejez az igen nagy számú eljárásváltozat megjelenése, a hozzájuk kifejlesztett hozag- és segédanyagok széles köre, a gépesítésük többféle lehetősége. Ezek együttese olyan hegesztés-technikai bázist jelent, amelyre egyaránt építhet konstruktőr, technológus és menedzser. Hogy ez az „építkezés” megalapozott lehessen, ahhoz a jelen könyv is hozzá kíván járulni a felsorolt témaegységek rendszerező, tömör szemléletű áttekintésével. Célja olyan elméleti és gyakorlati ismeretek összefoglalása, amelyek alátámaszt(hat)ják, illetve bővít(het)ik a hegesztéssel kapcsolatba kerülők háttérismereteit. Kompakt formában, enciklopédikusan igyekszik információkat nyújtani olvasóinak a hegesztés azon részterületeiről – a hegesztési és rokon eljárásokról, illetve a gépesítés lehetőségeiről – amelyeket egyszerűen technikai háttérnek is nevezhetünk.

Although procedures of fusion and press welding may be classified according to various aspects, the most typical one may be the energy source. According with this, different groups of welding procedures are to be distinguished on the basis of the use of electric arch or resistance heat, thermochemical reaction heat, mechanical (deformation and/or friction) energy as well as particle or electromagnetic radiation energy. The international standard classification of fusion and press welding procedures is correlated with the principle above. The first digit of the identity code of particular procedures and their variants (in case of the most widespread and important procedures) indicates the source of energy applied, the second refers to the technical endowment (the infrastructural arrangement), whereas the third serves to further differentiation between similar variants. Considering as criteria the source of the used energy, the most widespread fusion welding procedure is the arch welding, as well as the most significant press welding procedure is that using electrical resistance, The significance of the type of energy source is also indicated by the first digit of the code as follows: 1 for arch welding procedures and 2 for resistance welding procedures. Both goups of welding procedures are based on electrical phenomemons (more exactly, appartening to electricity, electrotechnics and electronics) and are realized as effect of heat produced by electricity. The basic infrastructural condition for all welding procedures is considered the welding equipment. As follows, cognition of the principle of functionning, of the build up and actioning of these equipments is essential. In order to perform the best exploitation of the performances of the welding equipment the technologist must have a continuous interest on the technical characteristics, the limits of parameters, the control of the system and the effects of this focusing on the work environment. Welding process parameters measurements and control solutions will be permanently taken in consideration. Focusing primarily on arch and resistance welding, the present book describes the theoretical and practical background, the technical characteristics and the related measurement, followed by the aspects of control and labour safety. It attempts to provide a survey of the particular fields of welding procedures mentioned above, which may support or expand the background knowledge of everyone interested in welding. It’s purpose consists in supplying the Reader information at a glance on some essential areas of welding like applications and measurement, control, and labour safety aspects).
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Az elektromos hegesztőberendezések alapfeltételét képezik a hozzájuk kapcsolódó hegesztési eljárásoknak, ezért fontossá válik alapelvük, felépítésük, működésük ismerete. Továbbá ahhoz, hogy hatékonyan kihasználhatók legyenek a bennük rejlő lehetőségek, célszerű foglalkozni alkalmazástechnikai jellemzőikkel: beállítási, illetve beavatkozási lehetőségeikkel, határértékeikkel, munkakörnyezeti hatásaikkal. Ennek szellemében a kapcsolódó mérésekre, irányítástechnikai megoldásokra is figyelmet kell szentelni. Természetesen nem szabad megfeledkezni az elektromosság veszélyeiről és azok elhárításáról sem. Ez a könyv elsősorban az ív- és az ellenállás-hegesztésre koncentrálva foglalkozik az alkalmazható berendezések, eszközök elvi és gyakorlati hátterével, üzemeltetési sajátosságaival, a kapcsolódó mérés-, irányítás- és biztonságtechnikai szempontokkal. Természetesen csak a teljesség igénye nélkül vállalkozik (vállalkozhat) a hegesztéstechnika felsorolt részterületeinek áttekintésére, amelyek alátámaszt(hat)ják, illetve bővít(het)ik a hegesztéssel kapcsolatba kerülők háttérismereteit. Viszonylag tömör, lényegre törekvő formában igyekszik információkat nyújtani Olvasóinak a hegesztés azon részterületeiről – a hegesztőberendezésekről, illetve azok mérés-, irányítás- és biztonságtechnikai vetületeiről –, amelyeket egyszerűen a hegesztéstechnikai háttérhez sorolhatunk.

In this study, a study on welding aluminum weldings with techniques such as TIG welding, MIG welding, Friction Stir welding, Laser Beam welding is compiled. Problems such as porosity, weld seam cracks and unstable arc that may occur as a result of the mentioned welding techniques have been investigated. The main purpose of this study is to examine the weldability of aluminum alloys and the causes and solutions of damage during or after welding. Apart from this purpose, information about the welding of aluminum alloys with other materials can be obtained. The effects of welding parameters on obtaining smooth welding products are mentioned. At the same time, the effect of the internal structure and chemical components of the alloys used on the welding process is not ignored.

In automobile industry, automobile welding fixture is a component which is important to auxiliary welding. The automobile body is welded by multiple complex sheet metal parts and other auxiliary work pieces. In this process, supporting role of welding fixture is an important role. In manufacturing of car, Truck, welding fixture was designed and analyzed briefly. The design of fixture demands extensive use of heuristic knowledge, which is also coupled. For instance, when define the machining operations of manufacturing parts in assembling of fixture solution should be kept in mind and vice versa. Fixture designers have a skill and experience for several years, in achieving proper fixture designs. In the Automobile Industry, BIW (Body In White) is the common terminology used to mention the car sheet metal welded structure (body shell). Sub-assemblies like Floor body, Body side, Left Hand Side/ Right Hand Side, Front End, Roof etc. gets welded together by various metal joining process e.g. resistance spot welding. The welding fixtures are holding devices of assemblies of Car body they have different operations (reverting, welding, and stud) of geometric of car body structure. Keyword: Welding Fixture; Welding Technique; Uses of software in design of fixture Catia; Fides; Unigraphics; I. INTRODUCTION The fixture is a special tool for holding a work piece in proper position during manufacturing operation. For supporting and clamping the work piece, device is provided. Frequent checking, positioning, individual marking and non-uniform quality in manufacturing process are eliminated by fixture. This increase productivity and reduce operation time. Fixture is widely used in the industry practical production because of feature and advantages. To locate and immobilize workpieces for machining, inspection, assembly and other operations fixtures are used. A fixture consists of a set of locators and clamps. Locators are used to determine the position and orientation of a workpiece, whereas clamps exert clamping forces so that the workpiece is pressed firmly against locators. Clamping has to be appropriately planned at the stage of machining fixture design. The design of a fixture is a highly complex and intuitive process, which require knowledge. Fixture design plays an important role at the setup planning phase. Proper fixture design is crucial for developing product quality in different terms of accuracy, surface finish and precision of the machined parts in existing design the fixture set up is done manually, so the aim of this project is to replace with hydraulic fixture to save time for loading and unloading of component. Hydraulic fixture provides the manufacturer for flexibility in holding forces and to optimize design for machine Operation as well as process function ability.

A laser beam welding process via heat conduction was applied to join DC01 steel with aluminum (Al)in overlap configuration without filler wire. The effect of the applied laser power (1.7, 1.8, 2.1, and2.4kW) on the formation and evolution of the interfaces between steel and Al was analyzed. Twointermetallic compounds were found at the interface, namely, one adjacent to the steel layer (Al
5
Fe
2
)and one close to the solidified Al (Al
13
Fe
4
). The thickness of the intermetallic reaction layer increaseswith laser power, while the morphology of its individual components evolves due to differences inaccumulated thermal cycles. Correlations between simulations and measurements show that the peaktemperature has significantly stronger influence on the thickness of the intermetallic reaction layerthan cooling time and the integral of temperature over the time. Shear/tensile strength tests reveal thatall the specimens fail in the Al heat affected zone

Laser welding is considered as a sophisticated, high precision and high speed joining process. In this process, laser beam is used as a heat source to join variety of materials such as aluminum, titanium, carbon steels, HSLA steels and stainless steels etc. Laser welding is currently being utilized in joining of miniature electronic components, steel structures, engine parts, transmission parts, alternators, solenoids, fuel injectors, fuel filters, air conditioning equipment and air bags etc. The present research paper discusses the recent research developments, process parameters, optimization techniques and applications of laser welding.

Laser welding of metals involves with formation of a melt-pool and subsequent rapid solidification, resulting in alteration of properties and the microstructure of the welded metal. Understanding and predicting relationships between laser welding process parameters, such as laser speed and welding power, and melt-pool characteristics have been the subjects of many studies in literature because this knowledge is critical to controlling and improving laser welding. Recent advances in metal additive manufacturing processes have renewed interest in the melt-pool studies because in many of these processes, part fabrication involves small moving melt-pools. e present work is a critical review of the literature on experimental and modeling studies on laser welding, with the focus being on the influence of process parameters on geometry, thermodynamics, fluid dynamics, microstructure, and porosity characteristics of the melt-pool. ese data may inform future experimental laser welding studies and may be used for verification and validation of results obtained in future melt-pool modeling studies.

Since welding technology is currently used to assemble the frame of driver's seats, it is important to develop laser welding technology for steel and aluminium. For this reason, the purpose of the present work was to examine the structure and selected properties of aluminium-steel joints using the example of an EN AW-6060 aluminium alloy and DC04 low-alloy steel welded in laser technology. Overlapping joints were made, weld type-following the hole laser welding method-laser beam (LB) using a high power disk laser (TRUMPF TruDisk3302), in which the active medium is a yttrium-aluminium crystal (YAG). Metallographic microstructure investigations were carried out using a light microscope from Carl Zeiss-Observer Z1m, and the weld microstructures were investigated using an SEM Supra 35 microscope, also from Carl Zeiss. The chemical composition analysis in micro-areas was carried out using an X-ray energy dispersion spectrometer from EDAX, which was a part of the SEM Supra 35. The hardness of the substrate material and the welded area was measured following the Vickers method using an FM-ARS 9000 micro hardness tester from Tokyo, Japan. It was found that there is a potential for commercial use of laser welding to make a low-carbon steel-aluminium alloy joint. During the formation of the weld in its microstructure, intermetallic compounds of the FexAly type were created, which significantly reduced the mechanical and plastic properties of the joint. The hardness of the weld created wasabout seven times higher than that of DC04 carbon steel. The choice of laser welding parameters (primarily, laser power and beam speed) significantly impacted the weld structure and properties.

In this work, samples of aluminium alloys 5083-T0 and 6082-T6 have been welded under conduction regime, using a high power diode laser. The influence of experimental variables, as the laser power and the linear welding rate, on the sizes and properties of the butt weld beads has been studied. In addition to measure the depths and widths of the weld beads, their microstructure, microhardness profile and corrosion resistance have been analysed. The results obtained allow one to define the experimental conditions leading to good quality butt welds with higher penetration than those published in the recent literature under conduction regime. Maximum penetration values of 3 and 2.3 mm were obtained for 5083 and 6082, respectively. Additionally, a simple mathematical expression relating the weld depth ( d) with the laser power ( P) and the processing rate ( v) has been proposed: d=(P-bb)/(av)-(ba)/a, being a, a', b and b' constant values for each alloy and under the employed experimental conditions. The values of these coefficients have been estimated from the fitting to the experimental depth values of 5083 and 6082 butt welds generated under conduction regime.

Misfit at the abutment-prosthetic cylinder interface can cause loss of preload, leading to loosening or fracture of gold and titanium screws. OBJECTIVES: To evaluate the influence of screw type, alloy, and cylinder position on marginal fit of implant frameworks before and after laser welding. METHODS: After Estheticone-like abutments were screwed to the implants, thirty plastic prosthetic cylinders were mounted and waxed-up to fifteen cylindrical bars. Each specimen had three interconnected prosthetic components. Five specimens were one-piece cast in titanium and five in cobalt-chromium alloy. On each specimen, tests were conducted with hexagonal titanium and slotted gold screws separately, performing a total of thirty tested screws. Measurements at the interfaces were performed using an optical microscope with 5mm accuracy. After sectioning, specimens were laser welded and new measurements were obtained. Data were submitted to a four-way ANOVA and Tukey's multiple comparisons test (a=0.05). RESULTS: Slotted and hexagonal screws did not present significant differences regarding to the fit of cylinders cast in titanium, either in one-piece casting framework or after laser welding. When slotted and hexagonal screws were tested on the cobalt-chromium specimens, statistically significant differences were found for the one-piece casting condition, with the slotted screws presenting better fit (24.13µm) than the hexagonal screws (27.93 µm). Besides, no statistically significant differences were found after laser welding. CONCLUSIONS: 1) The use of different metal alloys do exert influence on the marginal fit, 2) The slotted and hexagonal screws play the exclusive role of fixing the prosthesis, and did not improve the fit of cylinders, and 3) cylinder position did not affect marginal fit values.

Laser welding is a rapidly evolving and flexible technology that has found increasing industrial and manufacturing applications. It enables the precise welding of small and hard-to-reach areas and is particularly suitable for computer or robotic control operations. The laser welding technology describes the latest developments in the field and how they can be used across a wide range of applications. The fundamentals of laser welding discuss advancement in proven technologies such as CO2 disk laser welding, laser welding, and laser micro welding technology. Laser welding is a technique for aluminium and titanium alloys, plastics and glass. Applications of laser welding robotics and advances in laser and hybrid laser welding modelling and simulation. Laser welding applications is used in the automotive, rail and shipbuilding sectors. Due to its high precision, high-energy concentration and rapid processing potential, laser welding is particularly suitable for joining copper alloys in this context. High laser power needed due to low laser absorption, high copper thermal conductivity and low process stability. Laser welding of copper to other metals particularly copper to aluminium and copper to steel dissimilar alloys in terms of structure and properties relationships were also discussed.

Molten metal melt pools are characterised by highly non-linear responses, which are very sensitive to imposed boundary conditions. Temporal and spatial variations in the energy flux distribution are often neglected in numerical simulations of melt pool behaviour. Additionally, thermo-physical properties of materials are commonly changed to achieve agreement between predicted melt-pool shape and experimental post-solidification macrograph. Focusing on laser spot melting in conduction mode, we investigated the influence of dynamically adjusted energy flux distribution and changing thermo-physical material properties on melt pool oscillatory behaviour using both deformable and non-deformable assumptions for the gas-metal interface. Our results demonstrate that adjusting the absorbed energy flux affects the oscillatory fluid flow behaviour in the melt pool and consequently the predicted melt-pool shape and size. We also show that changing the thermo-physical material properties artificially or using a non-deformable surface assumption lead to significant differences in melt pool oscillatory behaviour compared to the cases in which these assumptions are not made.

The investigation of transient temperature profiles of a weld joint produced by the laser welding process is presented. A three-dimensional finite element model is developed using a commercial finite element code ANSYS in order to obtain the behavior of temperature field and molten pool shape during the welding process. A three-dimensional conical Gaussian heat source is employed as a heat source model for performing a non-linear transient thermal analysis. The temperature-dependent material properties of AISI 304 stainless steel sheet are taken into account, which has a great influence on the temperature fields indicated by the simulation results. The effect of latent heat and the convective and radiative boundary conditions are also included in the model. A series of laser welds are performed using a 2-kW continuous wave Nd:YAG laser welding system. The experimental trials are conducted by varying the laser input parameters namely beam power, welding speed, and beam incident angle to validate the model. The results show that there is a good agreement between the finite element simulation and the experimental observations.

In addition to their low cost and weight, polymer heat exchangers offer good anticorrosion and antifouling properties. In this work, a cost effective air-water polymer heat exchanger made of thin polymer sheets using layer-by-layer line welding with a laser through an additive manufacturing process was fabricated and experimentally tested. The flow channels were made of 150 μm-thick high density polyethylene sheets, which were 15.5 cm wide and 29 cm long. The experimental results show that the overall heat transfer coefficient of 35–120 W/m2 K is achievable for an air-water fluid combination for air-side flow rate of 3–24 L/s and water-side flow rate of 12.5 mL/s. In addition, by fabricating a very thin wall heat exchanger (150 μm), the wall thermal resistance, which usually becomes the limiting factor on polymer heat exchangers, was calculated to account for only 3% of the total thermal resistance. A comparison of the air-side heat transfer coefficient of the present polymer heat exchanger with some of the commercially available plain plate fin heat exchanger surfaces suggests that its performance in general is superior to that of common plain plate fin surfaces.