| Abstract Scope |
Challenges in the joining of dissimilar metals and alloys by laser beam welding (LBW), including differences in thermo-mechanical properties and intermetallic embrittlement, motivate the development of novel strategies to fabricate robust welds. Metallic interlayers deposited by a solid-state cold spray technique prior to LBW provide an opportunity to explore more dissimilar material combinations. The current investigation evaluates joints between stainless steel alloy SS304L and aluminum alloy AA6061. A cold-sprayed interlayer of SS304L is deposited onto the AA6061 substrate prior to partial penetration LBW of the interlayer to a similar SS304L coupon. Three LBW schedules (continuous wave, pulsed, circular beam oscillation/wobble) are investigated, with three different laser powers per schedule. All welds containing the interlayer (as-sprayed condition) stayed adhered to their substrates during welding and are found to be hermetic (5x10-9 ATM CC/s) using helium leak detection. The influence of post-deposition heat treatment on the cold spray interlayer is studied with respect to interlayer adhesion, porosity, strength and ductility. The weld region and interlayer interface are characterized using scanning electron microscopy (SEM), including energy-dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD). A spherical harmonic transform (SHT) method is used to re-index the EBSD datasets [ref: W. Lenthe et al, Ultramicroscopy, 207, 0304-3991 (2019)]. The mechanical behavior of the weld and constituent alloys is evaluated using microhardness and tensile testing.
Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. SAND#2026-21918A. |