About this Abstract |
| Meeting |
2025 AWS Professional Program
|
| Symposium
|
2025 AWS Professional Program
|
| Presentation Title |
Sigma Phase Formation in Vanadium-Stainless Steel Dissimilar Joints Produced With Various High Energy Density Welding and Additive Manufacturing Processes |
| Author(s) |
Erin Barrick, Cheryl Hawk, Ethan Hopwood, Andrew Kustas, Landon Schnebly, Christian Harris, Don Susan, Bernard Gaskey, Mikayla Obrist, Saryu Fensin, John Carpenter |
| On-Site Speaker (Planned) |
Erin Barrick |
| Abstract Scope |
Dissimilar metal welding of stainless steel to titanium alloys remains one of the most challenging combinations. The two alloy classes cannot be directly joined without the formation of brittle intermetallic phases in the fusion zone which compromises the integrity of the joint. Vanadium has been explored as a candidate interlayer alloy for this dissimilar combination, and while successful fabrication has typically been achieved with single pass laser welds, challenges have been encountered with other processes, such as laser beam directed energy deposition (LB-DED), due to the formation of sigma phase, a brittle intermetallic phase. In this work vanadium/stainless steel dissimilar joints were produced with 1) single pass laser welding, 2) laser beam directed energy deposition (LB-DED) of vanadium powder deposited onto stainless steel, and 3) electron beam directed energy deposition (EB-DED) of vanadium wire deposited onto stainless steel and vice versa. All joints were characterized with electron backscattered diffraction (EBSD) to understand phase formation in the fusion zones. Single pass laser welds of vanadium to stainless steel exhibited single phase BCC (i.e, no sigma phase) microstructures with high hardness in excess of 450 HV. Post-weld heat treatments were performed to understand the stability of the BCC phase and potential for subsequent transformation to sigma phase. Joints fabricated with LB-DED exhibited sigma phase formation and concomitant cracking/delamination of the vanadium build with the substrate. EB-DED single pass bead-on-plate welds demonstrated inhomogeneities with preference for sigma phase formation and a variety of different cracking mechanisms were correlated with sigma phase. The results of this work form the beginnings of a framework for kinetics of sigma phase formation in vanadium/stainless dissimilar welds based on cooling rates and repeat thermal cycles during AM.
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| Proceedings Inclusion? |
Undecided |