About this Abstract |
Meeting |
2020 AWS Professional Program
|
Symposium
|
2020 AWS Professional Program
|
Presentation Title |
Process, Microstructure and Fracture Mode of Magnesium to Steel Dissimilar Metal Spot Joints |
Author(s) |
Luke Walker, Colleen Hilla, Ying Lu, Menachem Kimchi, Wei Zhang |
On-Site Speaker (Planned) |
Luke Walker |
Abstract Scope |
A robust process to join magnesium alloy (Mg) to advanced high strength steel (AHSS) is important to the production of light-weight body structures for fuel-efficient vehicles. In addition to the common challenges in joining aluminum alloy to AHSS, joining Mg to AHSS possesses a unique difficulty as magnesium and iron are essentially immiscible. In this study, ultrasonic interlayered resistance spot welding (Ulti-RSW) was used to join 1-mm-thick (mmt) magnesium alloy AZ31 sheet and a 0.8mmt Zn-coated dual phase steel DP590 sheet. It made use of a 0.25mmt austenitic stainless steel 316 insert (or interlayer) which was first ultrasonic spot welded to the Mg sheet. Then the steel sheet was resistance spot welded to the insert side of the Mg sheet. Various parameters for ultrasonic spot welding and resistance spot welding were tested to improve the joint strength and fracture energy. The dissimilar metal joints were cross sectioned and the nugget geometry as well as the interface microstructure were characterized in optical and scanning electron microscopies. The joint strength was measured in quasi-static tensile (or lap) shear testing. The effect of welding parameters on the nugget sizes, interface microstructure, joint strength and failure mode was discussed. The joint microstructure and strength produced by Ulti-RSW were compared to those produced by direct RSW of Mg to Zn-coated DP590 steel. |
Proceedings Inclusion? |
Definite: Other |