With the growing demand for vehicle weight reduction and the increased application of multimaterial design, it is imperative to address the challenges of welding dissimilar light alloys. This paper presents a review on laser welding of Al/Mg, Al/Ti, and Mg/Ti alloys, with focus on the techniques used to suppress the formation of brittle intermetallic compounds (IMCs) and improve joining mechanism. For Al/Mg joints, studies have shown that the use of structural adhesives, the use of interlayers such as Ce, Ni, Ti, and Fe foils and Zn-Al filler metals, and hybrid adhesive-interlayers could suppress the formation of brittle IMCs and improve joint strength. The formation of brittle IMCs during laser welding of Al/Ti alloys could be minimized by offsetting the laser beam at an appropriate distance towards either the Al or Ti alloy, the use of split-beam laser with appropriate joint design, the use of high welding speed, improving the laser energy distribution, and the use of V-groove with Al-Si filler metals. For Mg/Ti alloys, offsetting the laser beam at an appropriate distance towards the Mg alloy, the use of AZ series Mg alloy-based filler wires, and coating the Ti alloy with Ni were found to facilitate the joint formation and improve the joint strength.

Challenges and advances in laser welding of dissimilar light alloys: Al/Mg, Al/Ti, and Mg/Ti alloys

Since its inception, laser beam welding as a high-quality fusion joining process has ascertained itself as an established and state of art technology exhibiting tremendous growth in a broad range of industries. This article provides a current state of understanding and detailed review of laser welding of titanium (Ti) alloys with corresponding dissimilar counterparts including steel, aluminium, magnesium, nickel, niobium, copper, etc. Particular emphasis is placed on the influence of critical processing parameters on the metallurgical features, tensile strength, hardness variation, percentage elongation and residual stress. Process modifications to improve dissimilar laser weldability by virtue of techniques such as laser offsetting, split beam, welding-brazing, hybrid welding and materials modifications by means of the introduction of single or multiple interlayers, fillers and pre-cut grooves are exploited. Detailed and comprehensive investigations on the phenomena governing the formation and distribution of the intermetallic phase, material flow mechanisms, their relations with laser parameters and their corresponding impact on the microstructural, geometrical and mechanical aspects of the welds are thoroughly examined. The critical issues related to the evolution of defects and the corresponding remedial measures applied are explored and the characteristics of fracture features reported in the literature are summarised in thematic tables. The purpose of this review is tantamount to emphasise the benefits and the growing trend of laser welding of Ti alloys in the academic sector to better exploit the process in the industry so that the applications are explored to a greater extent.

Current research and development status of dissimilar materials laser welding of titanium and its alloys

Influence of Si content on interfacial reactions and mechanical properties of dual-spot laser welded-brazed Ti/Al joints

Microstructure and mechanical properties of welding–brazing of Ti/Al butt joints with laser melting deposition layer additive

Microstructure and tensile properties of Ti/Al dissimilar joint by laser welding-brazing at subatmospheric pressure

https://hal.archives-ouvertes.fr/hal-01494324/document

Aluminum to titanium laser welding-brazing in V-shaped grooveI

It is ideal to observe the vapor plume to have a better understanding of the keyhole dynamics in dissimilar laser welding. This work is dedicated to the high-speed imaging and spectroscopic analysis of the vapor plume and postmortem analysis of melted zone produced from the interaction of a 6 ms Yb:YAG laser pulse with the aluminum A5754 - titanium T40 interface. These experiments are performed for different offsets of the laser spot from the joint line. The high-speed imaging is performed at two different wavelength (infrared 810 nm and ultraviolet 394 nm) regions. Morphological characteristics such as dimensions and orientation of the plume are studied and compared. The laser spot position affects the angle of inclination. It is observed that the plume inclines towards the aluminum side. The observation of inclination varies with the recording wavelength. The interrelationship between the inclination of the vapor plume and the laser spot position for a chosen observation wavelength is not self-explanatory. postmortem observation and EDX analysis of the melted zone, are correlated with the results from high-speed imaging. Spectroscopic analysis of the vapor plume associated with the Boltzmann linearization for temperature calculation, provides confirmation on the existing correlations between results from high-speed imaging and postmortem analysis. 

High-Speed Imaging of Vapor Plume in the treatment of Dissimilar Aluminum/Titanium Interface with Yb:YAG Laser Pulse

In the nuclear field, efforts are made to find substitutes to cobalt hardfacing alloys since these alloys have a principal drawback, the transmutation from stable 59Co to 60Co under neutron irradiation. In case of wear, fragments could be deposed on the surface of primary circuit and thus contaminate it, causing a real issue for deconstruction.

Coating Toughness Estimation through a Laser Shock Testing in Ni-Cr-B-Si-C Coatings

The investigation of keyhole behavior in dissimilar aluminum/titanium interface

La presente etude est dediee a la comprehension des facteurs influencant la resistance mecanique d’un assemblage entre l’alliage de titane Ti6Al4V avec l’alliage d’aluminium AA5754 par faisceau laser Yb:YAG. Le plan d’experiences propose a permis de mettre en evidence les effets des parametres operatoires sur la composition et la morphologie de la zone fondue ainsi que l’identification des conditions operatoires les plus favorables. L’etude numerique multiphysique basee sur l’utilisation de la methode des elements finis prenant en compte les transferts de chaleur, la mecanique des fluides et le transport des especes, a demontre les consequences des differences de proprietes thermo-physiques des materiaux a assembler, sur la creation de la liaison ainsi que le role des mouvements du liquide dans la formation d’une zone riche en phases intermetalliques.

M. Duband

Papers

Aluminum to titanium laser welding-brazing in V-shaped grooveI

High-Speed Imaging of Vapor Plume in the treatment of Dissimilar Aluminum/Titanium Interface with Yb:YAG Laser Pulse

Coating Toughness Estimation through a Laser Shock Testing in Ni-Cr-B-Si-C Coatings

The investigation of keyhole behavior in dissimilar aluminum/titanium interface

La compréhension et la maîtrise des jonctions hétérogènes titane-aluminium réalisés par faisceau laser