GOALI: Characterization of Material Transfer in Friction Stir Processing With a Consumable Tool

University Of Hawaii, Honolulu

Investigators

Abstract

This Grant Opportunity for Academic Liaison with Industry (GOALI) project will address the fundamental issue of material transfer from one metal to another at high force and temperature, called friction surfacing. This is based on friction stir welding technology in which a rotating tool is forced into a material to simultaneously deform, heat, and mix material. There is an increasing need for dissimilar material surfacing and coating applications. The major advantage of this technique is material adheres by mechanical bonding at relatively low temperature, resulting in high bonding strength, high tolerance to contamination, low environmental impact, and at low cost. The technical challenge centers on the nature of material transfer, adhesion and deposited material properties. This is collaborative research between the University of Hawaii at Manoa and General Motors. Two target applications have been identified for this research 1) Automotive - Conventional coating processes have not proven particularly suitable for steel and lightweight materials and have had limited success. What is therefore needed is an efficient and easily-operated technique to modify the surface composition of metal parts to make them more corrosion resistant. 2) Naval - the seals in ships are susceptible to corrosion and the current electroplating protection method is not adequate for coating nickel alloys onto the corroded, unclean steel hull. These industries are central to American national security and economic welfare. This research will also impact remanufacturing applications as an alternative method of coating/cladding by mechanical transfer of material. The PIs will work with native Hawaiian students on this research through the Native Hawaiian Science & Engineering Mentorship Program at the University of Hawaii at Manoa. The goal of this project is to characterize material transfer in friction surfacing with a consumable tool. The research will generate knowledge about parameters and conditions for transfer of material from one surface to another, which is important for all friction stir processes. The properties of tool and substrate for which material is being transferred will be characterized. The nature of adhesion between transferred material and substrate will be studied through a series of fundamental experimental measurements, metallurgy, and modeling to establish the relationship among the process parameters, process conditions, material transfer, and adhesion to the work material. The plan is to 1) experimentally measure the effects of process parameters and conditions on amount and quality of transferred material from the consumable tool to the rigid surface 2) establish metallurgy of the transferred material and adhesion 3) model the process for knowledge about distribution of stress, strain, and temperature throughout the material and 4) quantify the comparative performance and properties of the new coatings. This is a new direction for friction stir processing. General Motors is contributing much expertise and guidance to this project, which will enhance its technical relevance. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.