Physical Review B

Revisiting fundamental welding concepts to improve additive manufacturing: From theory to practice

Joining steel with aluminum involving the fusion of one or both materials is possible by laser beam welding technique. This paper describes a method, called laser braze welding, which is a suitable process to realize this structure. The main problem with thermal joining of steel/aluminum assembly with processes such as TIG or MIG is the formation of fragile intermetallic phases, which are detrimental to the mechanical performances of such joints. Braze welding permits a localized fusion of the materials resulting in a limitation on the growth of fragile phases. This article presents the results of a statistical approach for an overlap assembly configuration using a filler wire composed of 85% Zn and 15% Al. Tensile tests carried on these assemblies demonstrate a good performance of the joints. The fracture mechanisms of the joints are analyzed by a detailed characterization of the seams.

Dissimilar material joining using laser (aluminum to steel using zinc-based filler wire)

Laser welding–brazing (LWB) technique with CW Nd:YAG laser was used for lap joining of zinc coated steel (DP600) with aluminum alloy (AA6016) using a filler wire composed of 85% Zn and 15% Al. LWB was performed with varying laser power, brazing speed, and wire feed speed. The microstructure and composition analyses of the brazed joints were examined using SEM and EDS while the mechanical properties were measured in the form of micro-hardness and tensile strength. The thickness of reaction layers formed along the steel–seam interface was in the range of 3–23 μm, and it varied with the brazing speed. The average micro-hardness value of this layer was 348 HV, compared to 150 HV in brazed seam and 230 HV in steel matrix. It has been found that joints produced with heat inputs between 60 and 110 J/mm exhibited higher mechanical resistance of about 220 MPa and the failures occurred away from the joints on aluminum side. The corresponding brazing speeds are between 0.5 and 0.8 m/min and the thickness of the layer produced ranged between 8 and 12 μm.

Study on laser welding-brazing of zinc coated steel to aluminum alloy with a zinc based filler

Joining mechanism of Ti/Al dissimilar alloys during laser welding-brazing process

Introduction: Present work covers topic of strains and stresses prediction in case of Laser welded dissimilar titanium alloys structures. Dissimilar welding is used for weight and cost reduction considerations in the frame of aeronautic construction. Two dissimilar titanium alloys sheets (40 mm×100 mm) made in Ti50A and Ti6Al4V (Fig.1) are welded using a Nd:YAG continuous Laser source. A 3D unsteady numerical simulation was developed in order to assist in prediction of distortion for this kind of welded structure.

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Thermo-Mechanical Simulation of Dissimilar Titanium Alloys Laser welding

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.

Alexandre Mathieu

Papers

Thermo-Mechanical Simulation of Dissimilar Titanium Alloys Laser welding

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