Microstructures and Mechanical Properties of Dissimilar Al/Steel Butt Joints Produced by Autogenous Laser Keyhole Welding

Abstract

Dissimilar Al/steel butt joints of 6.0 mm thick plates have been achieved using fiber laser keyhole welding autogenously. The cross sections, interface microstructures, hardness and tensile properties of Al/steel butt joints obtained under different travel speeds and laser beam offsets were investigated. The phase morphology and thickness of the intermetallic compound (IMC) layers at the interface were analyzed by scanning electronic microscopes (SEM) using the energy-dispersive spectrometry (EDS) and electron back-scattered diffraction (EBSD) techniques. The results show that travel speeds and laser beam offsets are of considerable importance for the weld shape, morphology and thickness of IMC layers, and ultimate tensile strength (UTS) of Al/steel butt joints. This proves that the IMC layers consist of Fe 2 Al 5 phases and Fe 4 Al 13 phases by EBSD phase mapping. Increasing laser beam offsets from 0.3 mm to 0.7 mm significantly decreases the quantity of Fe 4 Al 13 phases and the thickness of Fe 2 Al 5 layers at the interface. During tensile processing, the Fe 2 Al 5 layer with the weakest bonding strength is the most brittle region at the interface. However, an intergranular fracture that occurred at Fe 2 Al 5 layers leads to a relatively high UTS of Al/steel butt joints.

3D Multiphysical Modelling of Fluid Dynamics and Mass Transfer in Laser Welding of Dissimilar Materials

“…Therefore, the mass transport of dissimilar metals increases, resulting in an increase in the thickness of the intermetallic reaction layer. As stated by Hu et al [11] and Yu et al [12], if the thickness of the intermetallic reaction layer is excessively large, intermetallic compounds may be produced to attenuate joint performance [24][25][26][27][28]. In addition, excessive Ti in the weld beam is also not conducive to welding quality.…”

Laser Welding

“…The present special issue on "Laser Welding" was a success with a total of 16 original research works published after peer-review. Different topics were discussed within this special issue: modelling and simulation of laser welding were presented in [1][2][3][4]; porosity control by means of high speed imaging and microscopy techniques was studied and discussed [5]; the effect of processing parameters on the microstructure and mechanical properties of laser-welded joints was evaluated for different metallic systems such as AZ31 alloy [6], steels [7][8][9][10], Ti-based alloys [11][12][13], and Al-based alloys [14]; and finally, dissimilar laser welding of aluminum to steel was presented [15,16].…”

Numerical Simulations and Experimental Validation on LBW Bead Profiles of Ti-6Al-4V Alloy

“…Advanced research is directed towards development of modeling and simulation tools, in addition to the process control in welding metallurgy (Wu et al, 2018;Ruan et al, 2018;Dal & Peyre, 2017;D'Ostuni et al, 2017;Popescu et al, 2017). Extensive studies are made on laser weld joint properties of metallic materials such as Al-based alloys (Zhang et al, 2017), AZ31 alloy (Lu et al, 2018), Al-steel (Cui et al, 2017;Casalino et al, 2017), steels (Górka & Stano, 2018;Mohammed et al, 2017;Xue et al, 2017;Evin & Tomáš, 2017), and Ti-based alloys (Zeng et al, 2017;Sánchez-Amaya et al, 2017;Caiazzo et al, 2017b). Mashinini & Hattingh (2018) have utilized LBW for joining 3 mm thick Ti-6Al-4V alloy sheets.…”