Hybrid laser arc welding simultaneously utilizes the arc welding and the laser welding, in a common interaction zone. The synergic effects of laser beam and eclectic arc in the same weld pool results in an increase of welding speed and penetration depth along with the enhancement of gap bridging capability and process stability. This paper presents the current status of this hybrid technique in terms of research, developments and applications. Effort is made to present a comprehensive technical know-how about this process through a systematic review of research articles, industrial catalogues, technical notes, etc. In the introductory part of the review, an overview of the hybrid laser arc welding is presented, including operation principle, process requirements, historical developments, benefits and drawbacks of the process. This is followed by a detailed discussion on control parameters those govern the performance of hybrid laser arc welding process. Thereafter, a report of improvements of performance and weld qualities achieved by using hybrid welding process is presented based on review of several research papers. The succeeding sections furnish the examples of industrial applications and the concluding remarks.

Hybrid laser arc welding: State-of-art review

Hybrid laser/arc welding of advanced high strength steel in different butt joint configurations

The electric vehicle (EV) battery systems are complex assemblies of dissimilar materials in which battery cells are connected using several thousand interconnect joints. Every single joint influences the functionality and efficiency of the whole battery system, making the joining process crucial. Laser welding is considered a desirable choice for EV battery manufacturing due to its non-contact nature, high energy density, precise control over the heat input, and ease of automation. However, incompatible thermos-physical properties of dissimilar materials used in battery tabs and interconnectors pose a significant challenge for achieving complete metallurgical bond. Furthermore, the formation of undesirable weld microstructures such as hard and brittle intermetallic compounds (IMCs) substantially undermines the structural, electrical, and thermal characteristics of battery joints. This paper reviews the fundamental difficulties and latest developments in dissimilar laser welding of steel-copper, steel-aluminum, aluminum-copper, and steel-nickel, some of the potential joint combinations in EV battery pack manufacturing. The weld microstructure and common metallurgical defects, as well as mechanical and electrical properties of joints are discussed. In addition, the effects of laser welding process parameters on the joint properties and the applicability of various interlayers and coatings in laser welding of battery materials are assessed.

A review on dissimilar laser welding of steel-copper, steel-aluminum, aluminum-copper, and steel-nickel for electric vehicle battery manufacturing

The electric vehicle (EV) battery systems are complex assemblies of dissimilar materials in which battery cells are connected using several thousand interconnect joints. Every single joint influences the functionality and efficiency of the whole battery system, making the joining process crucial. Laser welding is considered a desirable choice for EV battery manufacturing due to its non-contact nature, high energy density, precise control over the heat input, and ease of automation. However, incompatible thermos-physical properties of dissimilar materials used in battery tabs and interconnectors pose a significant challenge for achieving complete metallurgical bond. Furthermore, the formation of undesirable weld microstructures such as hard and brittle intermetallic compounds (IMCs) substantially undermines the structural, electrical, and thermal characteristics of battery joints. This paper reviews the fundamental difficulties and latest developments in dissimilar laser welding of steel-copper, steel-aluminum, aluminum-copper, and steel-nickel, some of the potential joint combinations in EV battery pack manufacturing. The weld microstructure and common metallurgical defects, as well as mechanical and electrical properties of joints are discussed. In addition, the effects of laser welding process parameters on the joint properties and the applicability of various interlayers and coatings in laser welding of battery materials are assessed. 

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In the present investigation, a numerical finite element model was developed to simulate the hybrid laser arc welding of different aluminum alloys, namely 5××× to 6××× series. The numerical simulation has been considered two double-ellipsoidal heat sources for the gas metal arc welding and laser welding. The offset distance of the metal arc welding and laser showed a significant effect on the molten pool geometry, the heat distribution and penetration depth during the welding process. It was confirmed that when the offset distance is within the critical distance the laser and arc share the molten pool and specific amount of penetration and dilution can be achieved. The models and experiments show that the off-distance between the two heat sources and shoulder width have considerable influence on the penetration depth and appearance of the weld beads. The experiments also indicate that the laser power, arc voltage and type of the filler metal can effectively determine the final properties of the bonds, specifically the bead appearance and microhardness of the joints. The experiments verified the numerical simulation as the thermocouples assist to comprehend the amount of heat distribution on the T-joint coupons. The role of the welding parameters on the mechanism of the hybrid laser welding of the aluminum alloys was also discussed.

Experimental and numerical investigations of hybrid laser arc welding of aluminum alloys in the thick T-joint configuration

Fiber laser-MIG hybrid welding of 5 mm 5083 aluminum alloy

Ensuring the precision and repeatability of component assembly in the production of electric vehicle (EV) battery modules requires fast and accurate measuring methods. The durability of EV battery packs depends on the quality of welded connections, therefore exact positioning of the module components is critical for ensuring safety in exploitation. Laser welding is a non-contact process capable of welding dissimilar materials with high precision, for that reason it has become the preferred joining method in battery production. In high volume manufacturing, one of the main production challenges is reducing the time required for assessment of dimensional and geometrical accuracy prior to joining. This paper reviews the challenges of EV battery design and manufacturing and discusses commercially available scanner-based measurement systems suitable for fabrication of battery pack components. Versatility of novel metrological systems creates new opportunities for increasing the production speed, quality and safety of EV battery modules.

Overview of Optical Digital Measuring Challenges and Technologies in Laser Welded Components in EV Battery Module Design and Manufacturing

The high power fiber laser has become one of the most efficient energy sources for deep penetration welding processes used in heavy manufacturing and marine industries. Combinations of cost-efficient, easily automatable process together with fairly mobile and flexible welding equipment have raised high expectations for improved quality and economic feasibility. In this study, the fillet welding of a low alloyed structural steel was studied using a 10 kW fiber laser. Plates of 8 mm thick AH36 were welded as a T-joint configuration in flat (1F) and horizontal (2F) positions using either an autogenous laser welding or a hybrid laser arc welding process. The effect of heat input on the weld bead geometry was investigated using one variable at a time approach. The impact of single process parameter such as laser power of 4.5–6 kW, welding speed of 0.5–2.5 m/min, beam inclination angle of 6°–15°, focal point position of −2 to +2 mm, and welding positions of 1F and 2F were studied. All welds were visually evaluated for weld imperfections described in EN ISO 13919-1 standard. Penetration depth, geometries of the fusion and heat affected zones, and hardness profiles were measured. Produced joints have a high depth to width ratio and a small heat affected zone; full penetration welds with acceptable weld quality on both sides of the joint were produced. The parameter configurations for optimizing the welding processes are proposed.

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Effect of welding parameters and the heat input on weld bead profile of laser welded T-joint in structural steel

Fiber laser and hybrid welding of T-joint in structural steels

Laser welding of thick plates in production environments is one of the main applications of high power lasers; however, the process has certain limitations. The small spot size of the focused beam produces welds with high depth-to-width aspect ratio but at times fails to provide sufficient reinforcement in certain applications because of poor gap bridging ability. The results of welding shipbuilding steel AH36 with thickness of 8 mm as a single-sided T-joint using a 10 kW fiber laser are presented and discussed in this research paper. Three optical setups with process fibers of 200 µm, 300 µm and 600 µm core diameters were used to study the possibilities and limitations set by the beam delivery system. The main parameters studied were beam inclination angle, beam offset from the joint plane and focal point position. Full penetration joints were produced and the geometry of the welds was examined. It was found that process fibers with smaller core diameter produce deeper penetration but suffer from sensitivity to beam positioning deviation. Larger fibers are less sensitive and produce wider welds but have, in turn, lower penetration at equivalent power levels.

Anna Unt

Papers

Fiber laser-MIG hybrid welding of 5 mm 5083 aluminum alloy

Overview of Optical Digital Measuring Challenges and Technologies in Laser Welded Components in EV Battery Module Design and Manufacturing

Effect of welding parameters and the heat input on weld bead profile of laser welded T-joint in structural steel

Fiber laser and hybrid welding of T-joint in structural steels

High Power Fiber Laser Welding of Single Sided T-Joint on Shipbuilding Steel with Different Processing Setups