2 Fundamentals of Friction Stir Welding, Its Application, and Advancements
73
was carried out in a shielded environment of argon gas because titanium and oxygen
react together to form the titanium oxide resulting in increased wear rate.
Lauro [142] investigated that the tool material selection is an important aspect of
titanium alloy. The tool should have sufficiently high-temperature resistance, better
tensile strength, excellent high-temperature hardness, high compressive strength
with exceptionally good toughness, and should be oxidation resistance at the higher
temperature. Mostly polycrystalline cubic boron nitride has wide application for
industrial application. The application limits due to extremely high cost, its brittleness
nature, and an unexpected failure during continuous service.
2.8.2 Dissimilar Welding Al–Cu, Al–Mg, Al–Steel
As a growing advancement, FSW has also evolved in the joining of dissimilar metal.
Dissimilar joints have applications in industrial, aerospace, and automobile to amalgamate two different metal properties in the components. This review has been
focused on the dissimilar joining of aluminum with copper, steel, and magnesium.
2.8.2.1 FSW of Aluminum and Copper
Dissimilar FSW of aluminum to copper has gained the utmost attention in different
fields. The dissimilar weld has great advantages in terms of cost and weight reduction. Due to which joining these materials is attractive for the aerospace, chemical,
electronic industries, and automobile sector.
Sinha et al. [143] have successfully FSWed Cu and Al. FSW joining of aluminum
alloy with copper was studied with varying rotational speed from 150 to 900 rpm.
Experiments were carried out in steps of 150 rpm at a fixed welding speed of
60 mm/min. Its microstructure and mechanical properties were studied which clearly
showed the formation of all the zones within the weld similar to FSW of the same
material. Also, it showed the formation of intermetallic phases Al 2 Cu 39 , Al 2 Cu,
AlCu, and Al 4 Cu at the interface of the stir zone.
Li et al. [144] investigated the FSW of pure copper with aluminum alloy. The pin
was shifted towards the aluminum side through a pin-offset method. Defect-free weld
was observed at 1000 rpm and 80 mm/min without the formation of intermetallic
phases. It resulted in a complex microstructural zone in the nugget zone with the
formation of a vortex-like pattern and lamella structure was found but the absence
of any intermetallic compounds in the weld nugget. Also, the hardness towards the
copper side of the nugget was higher as compared to aluminum alloy. The hardness
observed on the bottom side of the nugget is found to be higher than in other areas.
During the tensile test, the fracture surface at the joint of the dissimilar region failed
in a ductile–brittle mixed fracture mode. The weld strength and elongation were
found to be 152 MPa and 6.3%, respectively.
73
was carried out in a shielded environment of argon gas because titanium and oxygen
react together to form the titanium oxide resulting in increased wear rate.
Lauro [142] investigated that the tool material selection is an important aspect of
titanium alloy. The tool should have sufficiently high-temperature resistance, better
tensile strength, excellent high-temperature hardness, high compressive strength
with exceptionally good toughness, and should be oxidation resistance at the higher
temperature. Mostly polycrystalline cubic boron nitride has wide application for
industrial application. The application limits due to extremely high cost, its brittleness
nature, and an unexpected failure during continuous service.
2.8.2 Dissimilar Welding Al–Cu, Al–Mg, Al–Steel
As a growing advancement, FSW has also evolved in the joining of dissimilar metal.
Dissimilar joints have applications in industrial, aerospace, and automobile to amalgamate two different metal properties in the components. This review has been
focused on the dissimilar joining of aluminum with copper, steel, and magnesium.
2.8.2.1 FSW of Aluminum and Copper
Dissimilar FSW of aluminum to copper has gained the utmost attention in different
fields. The dissimilar weld has great advantages in terms of cost and weight reduction. Due to which joining these materials is attractive for the aerospace, chemical,
electronic industries, and automobile sector.
Sinha et al. [143] have successfully FSWed Cu and Al. FSW joining of aluminum
alloy with copper was studied with varying rotational speed from 150 to 900 rpm.
Experiments were carried out in steps of 150 rpm at a fixed welding speed of
60 mm/min. Its microstructure and mechanical properties were studied which clearly
showed the formation of all the zones within the weld similar to FSW of the same
material. Also, it showed the formation of intermetallic phases Al 2 Cu 39 , Al 2 Cu,
AlCu, and Al 4 Cu at the interface of the stir zone.
Li et al. [144] investigated the FSW of pure copper with aluminum alloy. The pin
was shifted towards the aluminum side through a pin-offset method. Defect-free weld
was observed at 1000 rpm and 80 mm/min without the formation of intermetallic
phases. It resulted in a complex microstructural zone in the nugget zone with the
formation of a vortex-like pattern and lamella structure was found but the absence
of any intermetallic compounds in the weld nugget. Also, the hardness towards the
copper side of the nugget was higher as compared to aluminum alloy. The hardness
observed on the bottom side of the nugget is found to be higher than in other areas.
During the tensile test, the fracture surface at the joint of the dissimilar region failed
in a ductile–brittle mixed fracture mode. The weld strength and elongation were
found to be 152 MPa and 6.3%, respectively.