Abstract

We are currently living through an era characterized by advancements in artificial intelligence, machine learning, and additive manufacturing. This new age reflects the integration of digital technologies with advanced manufacturing processes in a way that allows us to revolutionize the way complex multi-material components are imagined, designed, produced, and utilized, leading to unprecedented levels of innovation and efficiency in manufacturing and beyond. An example of a complex multi-material component is the tailor-welded blank (TWB) which is used in the automotive industry to produce lightweight, safe, and crash-resistant modern vehicles. These blanks are produced by laser-welding different press-hardened steels to create components that can later be stamped into the desired shape and geometry to offer tailored properties that can be controlled based on the structural needs of the component under high dynamic loads. However, the laser welding of aluminum-silicon (Al-Si) coated PHSs results in the formation of a softer ferrite phase in the welded joint which is attributed to the mixing of the Al-Si coating in the molten weld pool, resulting in a catastrophic premature failure of the joint. Current industry practice involves pre-weld removal of the Al-Si layer through laser ablation, but this can be costly and time-consuming. This presentation discusses the use of in-situ alloying of Ni during laser welding to solve the issue of softening without the prior removal of the Al-Si coating. Research findings have shown that the introduction of Ni as an austenite stabilizing element into the joint can decrease ferrite content and increase weld strength without sacrificing process efficiencies. This presentation will analyze the in-situ alloying effect of Ni on the morphology, crystallography, and mechanical properties of laser welded 22MnB5, offering insights into how advanced in-situ materials processing techniques can be used for diverse applications in several important industries.  

Keywords: Fiber laser welding; press-hardened steels; ferrite suppression; tailor-welded blanks; coating ablation; austenite stabilizing elements; hot stamped steel; Al-Si coated 22MnB5

Bio

Dr. Muhammad Shehryar Khan is a Banting Postdoctoral Fellow in the field of advanced materials processing within the Department of Materials Science and Engineering at MIT. He also serves as an adjunct professor in the Department of Mechanical and Mechatronics Engineering at the University of Waterloo, from where he received his Ph.D. in Mechanical and Mechatronics Engineering. He is a recipient of the Governor General’s Gold Medal, and several other notable national and international scholarships and awards. Dr. Khan works in the realm of advanced materials processing with his core research interests lying at the intersectional understanding of relationships between process, microstructure, and properties of materials, with a focus on advancing the fields of mechanical engineering, materials science, and advanced manufacturing. He has a keen interest in addressing real-world processing and advanced materials related challenges faced by various industries including automotive, aerospace, and the energy sectors. He has published research related to process optimization and metallurgy of high-speed and high-powered laser welding and cladding of steels and other materials. He has also published fundamental studies related to a non-fusion joining process called weld-brazing that uses Cu-based filler materials to join high strength steels used in the automotive industry. He specializes in similar and dissimilar joining of structural materials, focusing on various issues related to industrial metallurgy ranging from liquid metal embrittlement of Zn-coated steels to microstructural refinement of steels using in-situ alloying and processing techniques. He is currently utilizing laser-induced particle impact testing (LIPIT) at MIT to study fundamental issues related to cold spraying technology, which is a solid-state powder deposition process that achieves impact-induced mechanical or metallurgical bonding at extremely high strain rates. His ongoing research explores bonding mechanisms for various materials, including pure metals and alloys, to shed light on solid-state bonding behaviors in industrially relevant dissimilar materials.