Engineering a Proprietary and Economical Filler for Ductile Brazing of Metals & Critical Metals
Presented by:
Prof. Zhenzhen Yu
Colorado School of Mines
Abstract:
Brazing is a critical joining process for assemblies that demand high geometric precision or careful control of material inter-dilution with similar and dissimilar material joining cases. The choice of filler metal requires balancing several factors: (1) the thermal compatibility of the substrate(s) with the filler’s recommended brazing temperature, to ensure controlled microstructure evolution; (2) the phase constituents that form in the joint as the filler dilutes into the substrates; and (3) the long-term reliability of the brazed component under service conditions. However, existing brazing filler metals, especially for brazing of Ni-base alloys and steels, with boron and silicon as melting-point depressants often fall short in providing adequate ductility, especially at wide gap widths, necessitating the use of expensive noble metal fillers based in gold and palladium to be used instead. This work built a fast screening material design engine to develop new multi-principal element braze filler compositions designed for brazing steels and Ni-base alloys in two disparate temperature ranges approximately 990 – 1050°C and 1170 – 1200°C. Metallurgical characterization of brazed joints demonstrated complete metallurgical compatibility with their substrate material(s) with accommodation of base material elements and no terminal intermetallic phases in the resultant joint metal regardless of the initial joint clearance. Significant improvement was also observed in the mechanical testing results compared with existing braze fillers. For instance, brazing of a single-lap Joint stainless-steel geometry with fixed 50µm clearance using the new filler produced gains of 460% in elongation over BNi-5 filler, along with a 65% increase in engineering shear strength.
Bio :
Prof. Zhenzhen Yu is an Associate professor in the department of Metallurgical and Materials Engineering at Colorado School of Mines (CSM) and co-founder of HYSA Fillers LLC that tackles challenges in metallurgical joining and repair.
Dr. Yu currently also serves as site director of NSF I/UCRC Manufacturing & Materials Joining Innovation Center (Ma2JIC) and Director of the Center for Welding, Joining and Coating Research (CWJCR) at CSM. She received MS and PhD degrees from the Department of Materials Science and Engineering at the University of Tennessee, Knoxville. Her research interests include weld metallurgy, development of similar/dissimilar joining technologies, consumables design, and simulation and characterization of transient material states during welding. She received the American Welding Society District Educator Award, National Science Foundation Faculty Early Career Development CAREER Award, Prof. Koichi Masubuchi Award, and best paper awards such as James. F. Lincoln Gold Medal, McKay-Helm and the A.F. Davis Silver Medal Awards
Meeting Sponsor:
Contact Jean Marc Tetevuide
Evening Schedule:
5:00pm: Doors open; Check-In open
5:00pm - 6:00pm: Social Hour and Networking
6:00pm - 7:00pm: Dinner (included with registration)
7:00pm - 8:00pm: Technical Presentation and Q&A
8:00pm: Meeting Closed