Laser-Assisted Forming of Ultra-High Strength Steels: A Critical Review of Mechanisms, Processes, and Future Directions

Ultra-high strength steels (UHSS) are critical for lightweighting in the automotive and aerospace industries, but their poor room-temperature formability presents a significant manufacturing barrier. Laser-assisted forming (LAF) has emerged as a key enabling technology that utilizes localized laser heating to reduce forming forces, enhance ductility, and mitigate springback. This paper provides a critical review of the state-of-the-art in LAF of UHSS. It begins by elucidating the governing principles, including the coupled thermo-mechanical and metallurgical mechanisms such as thermal softening, dynamic microstructure evolution, and non-equilibrium phase transformations. The review then systematically surveys the major LAF process variants—including bending, roll forming, and incremental forming—and their applications in fabricating complex UHSS components. Despite its proven advantages, significant challenges impede its widespread industrial adoption. The most critical issues are identified and discussed, including local mechanical property degradation due to uncontrolled thermal cycles, the complexity of predictive multi-physics modeling, and the need for robust in-situ process monitoring and control. Ultimately, this review presents a forward-looking perspective, proposing future research directions that focus on microstructure management, the development of high-fidelity digital twins, and the implementation of intelligent closed-loop control systems to ensure process stability and part integrity. This work provides a comprehensive roadmap for advancing the science and technology of LAF for next-generation lightweight manufacturing.