Welding of Dissimilar Steel/Al Joints Using Dual-Beam Lasers with Side-by-Side Configuration

Abstract

Welding of dissimilar steel/Al lapped joints of 1.5 mm in thickness was carried out by using dual-beam laser welding with side-by-side configuration. The effect of the major process parameters including the dual-beam power ratio of (Rs) and dual-beam distance (d1) on the steel/Al joint characteristics was investigated concerning the weld shape, interface microstructures, tensile resistance and fracture behavior. The results show that dual-beam laser welding with side-by-side configuration produces soundly welded steel/Al lapped joints free of welding defects. The processing parameters of Rs and d1 have a great influence on the weld appearance, the weld penetration in the Al alloy side (P2) and the welding defects. Variation in the depth of the P2 and the locations at the Al/weld interface cause heterogeneous microstructures in the morphology and the thickness of the intermetallic compound (IMC) layers. In addition, electron back scattered diffraction (EBSD) phase mapping reveals that the IMC layer microstructures formed at the Al/weld interface include the needle-like θ-Fe4Al13 phases and compact lath η-Fe2Al5 layers. Some very fine θ-Fe4Al13 and η-Fe2Al5 phases generated along the weld grain boundaries of the steel/Al joints are also confirmed. Finally, there is a matching relationship between the P2 and the tensile resistance of steel/Al joints, and the maximum tensile resistance of 109.2 N/mm is obtained by the steel/Al joints produced at the Rs of 1.50 during dual-beam laser welding with side-by-side configuration. Two fracture path modes have taken place depending on the P2, and relatively high resistance has been achieved for the steel/Al joints with an optimum P2.

Dissimilar Metal Welding

“…This special issue of Metals covers sixteen articles [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] focused on dissimilar metal joining techniques. Some of the published reports have confirmed the increasing interest in solid state welding processes, in particular friction based welding [6][7][8][9][10] and electromagnetic pulse welding [11,12], due to benefits related to the properties and achievable microstructure, and to energy and environmental considerations.…”

“…Some of the published reports have confirmed the increasing interest in solid state welding processes, in particular friction based welding [6][7][8][9][10] and electromagnetic pulse welding [11,12], due to benefits related to the properties and achievable microstructure, and to energy and environmental considerations. Other papers dealt with fusion welding techniques, mainly laser based [13][14][15][16], among others [5,17], and brazing processes [18,19]. Most of the applications are related to the automotive and aerospace sector, nevertheless dissimilar joints, characterized by improved fracture resistance, were indicated as an indispensable part of nuclear power plants for connecting the safe end (austenitic stainless steel 316L) to the pipe-nozzle (ferrite low-alloy steel A508) [20].…”

“…As far as dissimilar fusion welding processes are concerned, relevant efforts have been directed toward laser based methods [13][14][15][16]. Dual-beam laser welding has been investigated for dissimilar welding of steel/Al [13].…”

“…As far as dissimilar fusion welding processes are concerned, relevant efforts have been directed toward laser based methods [13][14][15][16]. Dual-beam laser welding has been investigated for dissimilar welding of steel/Al [13]. Cui et al studied the effect of the major process parameters, including the dual-beam power ratio and dual-beam distance on steel/Al joint features, in terms of weld shape, interface microstructure, tensile resistance and fracture behaviour.…”

“…Cui et al studied the effect of the major process parameters, including the dual-beam power ratio and dual-beam distance on steel/Al joint features, in terms of weld shape, interface microstructure, tensile resistance and fracture behaviour. Intermetallic compound (IMC) layer formation (needle-like θ-Fe4Al13 phases) was also highlighted [13]. The article by Pereira et al [14] deals with dissimilar metal laser welding between DP1000 Steel and AA1050, by employing a pulsed Nd: YAG laser.…”