Effects of the adjustable ring-mode laser on intermetallic formation and mechanical properties of steel to aluminium laser welded lap joints

Research has confirmed a positive effect of laser beam shaping on controlling weld profiles and keyhole stabilisation, with significant reductions of porosity in weldments. However, few attempts with scattered results have studied the impact of laser beam shaping on intermetallic phase formation. This paper implements the adjustable-ring mode (ARM) laser and studies the impact of the core/ring power ratio to explore the impact on intermetallic phase formation and mechanical properties during remote laser welding of IF steel to 1050 aluminium. It was found that in conduction mode, the core/ring power ratio of 0.2 provided a larger surface area for bonding at the weld interface, and this was translated through the maximum lap-shear strength of 97.6 N/mm2 (joint efficiency 71%). Furthermore, this significantly reduced the Fe2Al5 intermetallic compound (IMC) thickness by 62% and total IMC thickness by 40% in contrast to a core-dominant beam (power ratio greater than one). In keyhole mode, cracking and lower lap-shear strengths were observed compared to the conduction mode. Notably, with a core/ring power ratio of 0.5 a significant grain refinement in the steel side of the weld was observed

Effects of the adjustable ring-mode laser on intermetallic formation and mechanical properties of steel to aluminium laser welded lap joints

Research has confirmed a positive effect of laser beam shaping on controlling weld profiles and keyhole stabilisation, with significant reductions of porosity in weldments. However, few attempts with scattered results have studied the impact of laser beam shaping on intermetallic phase formation. This paper implements the adjustable-ring mode (ARM) laser and studies the impact of the core/ring power ratio to explore the impact on intermetallic phase formation and mechanical properties during remote laser welding of IF steel to 1050 aluminium. It was found that in conduction mode, the core/ring power ratio of 0.2 provided a larger surface area for bonding at the weld interface, and this was translated through the maximum lap-shear strength of 97.6 N/mm2 (joint efficiency 71%). Furthermore, this significantly reduced the Fe2Al5 intermetallic compound (IMC) thickness by 62% and total IMC thickness by 40% in contrast to a core-dominant beam (power ratio greater than one). In keyhole mode, cracking and lower lap-shear strengths were observed compared to the conduction mode. Notably, with a core/ring power ratio of 0.5 a significant grain refinement in the steel side of the weld was observed

Finite element simulation and experimental investigation of hot forming cold die quenching and equal channel angular pressing of AA2024 aluminum alloy

The present study investigates the variations in the microstructure and mechanical properties of AA2024 aluminum alloy as a consequence of thermal and strain gradient in combined hot forming cold die quenching (HFQ) and equal channel angular pressing (ECAP) method. Solution-treated AA2024 aluminum alloy was HFQ–ECAPed for five passes of deformation and 3D simulations plus microstructural evolutions, and mechanical properties over the thickness of the sample were investigated. Furthermore, after each ECAP pass, intermediate solution treatment was applied, and a group of specimens was subjected to aging treatment following the deformation. 3D simulations illustrated strain uniformity by increasing the number of deformation passes with its maximum uniformity after four passes. Microstructural observations demonstrated evident grain refinement in successive passes, which were higher in the central and top parts of the sample than in the lower area. Also, a high quantity of shear bands occurred in the workpiece after the first ECAP pass. However, shear banding was deducted in the consecutive passes of deformation and intermediate solutionizing. Preferable properties in central regions were seen comparing tensile properties in surface area and central parts. Besides, the microhardness test resulted in more uniform outcomes by enhancement in the number of ECAP passes. Hardness variations showed an increase in average hardness after the first pass of deformation (compared to the annealed condition (Baghbani Barenji et al. in J Mater Res Technol 9:1683–1697, 2020) and then a negligible decrease in the following two passes. The hardness quantities again increased in the fourth pass and then dramatically decreased after the fifth pass due to the partial decomposition of the solid solution. Besides, due to strain distribution, hardness values illustrate the maximum and minimum amount in the uppermost and lowermost areas, respectively. The overall conclusions of this article presented mechanical similarities in the surface and inner parts of the material