About this Abstract |
| Meeting |
2026 AWS Professional Program
|
| Symposium
|
2026 AWS Professional Program
|
| Presentation Title |
Laser Hybrid Tack Welding of HSLA Steel Fillet Weld Joints: Microstructure Influence in Final Weldments |
| Author(s) |
Benjamin Schneiderman, Jonathan Roberts, Kevin Roossinck, Zhenzhen Yu |
| On-Site Speaker (Planned) |
Benjamin Schneiderman |
| Abstract Scope |
Handheld laser welding systems can produce small fillet welds with deep penetration, offering a convenient alternative to conventional methods for shipbuilders looking to eliminate oversized tack welds when joining large sections of high-strength low-alloy (HSLA) steel plate. This technique is particularly beneficial because the low heat input minimizes part distortion while providing highly localized joint restraint prior to the main welding pass, e.g., with flux cored arc welding (FCAW). However, the influence of handheld laser tack welding on the final weldment microstructure and impact toughness has not been fully explored. This work investigated laser tack fillet welds of HSLA-65 that were subsequently over-welded by conventional FCAW. While the high heat input of the FCAW process successfully consumed and re-melted the vast majority of the laser tack weld metal, certain joint geometries and local variations in fit-up led to the retention of a re-heated but un-melted zone of tack weld metal near the weld root, spanning 1–2 mm2 in cross-sectional area. Optical microscopy identified this unconsumed zone as the primary region of interest for potential debits to weldment impact toughness. Metallurgical characterizations revealed that while the unconsumed laser tack weld displayed microhardness similar to equivalent FCAW heat-affected zone regions in untacked base material, it exhibited distinct microstructural features. Specifically, higher fractions of upper and lower bainite along with a 50–70% increase in the area fraction of martensite-austenite (M-A) constituents were observed. These localized microstructural features suggest a heightened susceptibility to embrittlement within the small unconsumed tack zones. The absence of unconsumed tack weld metal in majority of the specimen sets suggests strategic manual positioning of the handheld laser may mitigate the unconsumed zone. Alternatively, within the identified laser parameter windows, increasing the wobble parameter may create shallower and wider pool geometries more likely to be completely re-melted by FCAW. |
| Proceedings Inclusion? |
Undecided |