Abstract
This work describes the effect of newly introduced faying surfaces on the microstructure and the mechanical properties of dissimilar weld joints of AA6063 and AISI304L alloys that are fabricated through the rotary friction welding process (RFW). The experiments were done as six different experimental methods (‘A’ to ‘F’) at 1300 rpm rotation, 18 MPa friction pressure (FP), 24 MPa upset pressure (UP) and 5 s friction time (FT) with the faying surfaces of hemispherical bowl and thread of 1 mm pitch on the weld specimens. The fabricated joints and the weld zones were characterized by macro and microstudy, energy dispersive X-ray spectroscopy (EDS) spectrums, tensile properties, Vickers microhardness, impact toughness and fractography. The results showed that these faying surface modifications strengthen the bonding between the weld specimens and influences the performance of the joints. The hemispherical bowl showed better results than the threaded surfaces. Axial shortenings were within the acceptable limit in the range of 20–27 mm. Macro and microstructural studies showed the defect-free weld joints and the strong bonding between AA6063 and AISI304L alloys. The hemispherical faying surface on AISI304L alloy formed a U-shaped weld interface (WI) in the dissimilar joints. EDS proved the formation of the Fe–Al intermetallic and the element ‘O’ at weld zone. The joint efficiency for all the methods was around ≥100%. Maximum tensile strength was recorded as 238 MPa for method F. The threaded surface showed good hardness property nearby WI, and method A yielded maximum impact toughness for the joint.
Highlights
As the different chemical compositions and materials properties, joining of stainless steel with aluminium is difficult by fusion welding processes [1]
From the weld flash shown in figure 5(a), it is observed that the faying surface modifications may show their effect on the metal flash expelled during the application of frictional force during the friction welding
In method ‘C’, the penetration of threaded AISI304L alloy is about 5 pitches into AA6063 alloy as the threaded faying surface of AA6063 stimulates the bonding between AISI304L and AA6063 specimens during Friction welding (FW) (Figure 5(d))
Summary
As the different chemical compositions and materials properties, joining of stainless steel with aluminium is difficult by fusion welding processes [1]. Zinda et al [5] researched the frictional joining between aluminium (5A33) and magnesium (AZ31B) alloys and reported that the tensile strength increased with the increase of the FT (5 sec) and the formed intermetallics improved the hardness of joints. Prasanthi et al.[14] successfully welded mild steel with titanium rod of φ10mm x100mm size using the FW process Through their study, they confirmed the formation of fine Fe-Ti intermetallic phase at the weld interface and the hardness of 350 VHN was obtained at the interface. This study aims to identify the welding feasibility and the joint efficiency of the different experimental methods tried on these base metals through rotary friction welding machine
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