Perpendicular ultrasonic joining of steel to aluminium alloy plates

Abstract

Standard and high strength steel plates were successfully joined to A2017 and A6061 aluminium plates by applying ultrasonic power perpendicular to the joint interface instead of tangentially, as in other ultrasonic joining methods Using a 2.9 mm diameter tip, cross tensile strengths of 281 N and 460 N were obtained when joining 0.5 mm thick A6061 plates to 0.5 mm thick commercial and high steel plates, respectively. When joining 0.5 mm thick A2017 plates, the cross tensile strengths were 343 N and 437 N, respectively. Temperature measured at less than 1mm from the joining interface did not exceed 135 • C in any case. The joining mechanisms and resulting joint characteristics are investigated and discussed, alongside parameters affecting the resulting joint performance. Under optimal joining conditions, the cross tensile tests and cross section observations revealed that material fracture resulted in plug failure. No intermetallic layer has been detected with SEM analysis. The joint strengths obtained under those conditions were the maximum attainable for the tip diameter used, provided that they correspond to the stress intensities required to propagate cracks in the aluminium. These results support the conclusion that this ultrasonic joining method, being operationally similar to the method used in resistance spot welding, and providing good performance joints, could be used successfully for high throughput indus-trial applications taking advantage of the available spot welding tooling and operational procedures, as tangential movement of the whole plate is not required.

Mechanical Characterization of AA 6061-T6 MIG Welded Aluminum Alloys Using a Robotic Arm

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Experimental Study and Numerical Simulation of Interfacial Morphology by Electromagnetic Pulse Welding with Aluminum to Steel

“…Lightweight and corrosion-resistant materials (e.g., aluminum and aluminum alloys) have become the substitutes for traditional steel, and gradually been applied in the fields of aerospace, shipbuilding, and railways. However, due to the large difference in thermophysical properties between aluminum and steel, the brazing filler metal makes the welded joint more brittle; 1) for laser welding, relatively large heat input cause uneven composition of the weld seam, which is very easy to generate large internal stress; 2) uneven heat-machine coupling in friction welding. 3) Therefore, it is particularly necessary to select a welding method suitable for aluminum and steel.…”

Multi-Spot Ultrasonic Welding of Aluminum to Steel Sheets: Process and Fracture Analysis

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