Joining aluminum to steel can lighten the weight of components in the automobile and other industries, which can reduce fuel consumption and harmful gas emissions to protect the environment. However, the differences of thermal, physical, and chemical properties between aluminum and steel bring a series of problems in laser welding. The main problems are how to control the thickness of the intermetallic compound layer and reduce or avoid the generation of pores, cracks, and thermal stresses which severely limit the mechanical properties of welded joints. Laser fusion-brazing technology utilizes the precise control of heat input with or without filler to partially melt the low melting temperature aluminum base material and promote wetting on the high melting temperature steel base material in order to achieve sound metallurgical by combining the advantages of fusion welding and brazing. Different forms of laser beam welding including single beam laser welding, dual-beam laser welding, and laser arc hybrid fusion-brazing welding are reviewed.

Laser welding dissimilar materials of aluminum to steel: an overview

Friction stir welding exploits its solid state process behaviour to join aluminum to steel, which differs in thermal and mechanical properties, and where combination of these metallic alloys by fusion welding prompts a deleterious reaction as a result of the melting and resolidification phases. This review investigates the distinction and characterization of aluminum to steel joints made by this welding method. An attempt to address sub-techniques into three categories i.e., diffusion, plunging, and annealing, is made. Steel fragments spattered at the weld zone, weld defects, sharp difference in grain size distribution, and the formed phases of the intermetallic layer and its thickness are discussed, these factors and the process welding parameters are significantly influenced the joint’s strength of this welding method.

Characteristics of aluminum-to-steel joint made by friction stir welding: A review

Dissimilar MIG-CMT weld-brazing of aluminium to steel: A review

In this research, dissimilar butt joining of an Al–Mg alloy (AA5083) to austenitic stainless steel (A316L) by using friction-stir welding (FSW) process was examined. FSW parameters and joint design were optimized, owning to achieve the best joint strength. The processed FSWs at the optimized traverse speeds of 16, 20, and 25 mm/min with the sound surface appearance were considered for further cross-sectional investigations, microstructural characterizations, and mechanical testings. In situ reactions at the interface of Al–Mg alloy and stainless steel during FSW processes were studied by using field emission-scanning electron microscopy (FE-SEM) and line-scan energy-dispersive X-ray spectroscopy (EDS) analysis. As expected from the monitored thermal histories during FSW joining, the features indicating the formation of tunneling like defects were observed at low heat inputs (low w/v ratios). Moreover, some discontinuous thin intermetallic layers (with the thickness of ∼0.5 μm) were formed at the joint interface at the expressed processing conditions. Mechanical performances of the prepared dissimilar joints were assessed during transverse tensile loading and Vickers indentation micro-hardness testing. The joint strength ratio to the ultimate tensile strength (UTS) of the weakest base metal (BM) was improved up to ∼93 %, as all of the dissimilar FSWs failed from the Al–Mg base alloy, with a Vickers hardness enhancement of ∼460 % at the interface.

Microstructural characteristics and mechanical properties of the dissimilar friction-stir butt welds between an Al–Mg alloy and A316L stainless steel

Effects of heat input on wettability, interface microstructure and properties of Al/steel butt joint in laser-metal inert-gas hybrid welding-brazing

http://www.ysxbcn.com/down/2014/04_en/12-p0989.pdf

Shu-jun Wang

Papers

Microstructures and properties of welded joint of aluminum alloy to galvanized steel by Nd:YAG laser + MIG arc hybrid brazing-fusion welding