WE-MSE Colloquium: Lee Semiatin, AFRL R&D on Inertia Friction Welding of Nickel-Base Superalloys

Senior Scientist, Materials Processing/Processing Science, Air Force Research Laboratory

All dates for this event occur in the past.

264 MacQuigg Labs
105 W. Woodruff Ave.
Columbus, OH 43210
United States

This will be a joint WE-MSE Colloquium held at 3:00 p.m. in 264 MacQuigg Labs.

 

Abstract

An overview of recent R&D performed by AFRL (some in conjunction with OSU) in the area of inertia friction welding (IFW) of gamma-prime-strengthened, nickel-base superalloys will be presented. This work has focused on three major areas – process mechanics, material behavior during IFW, and the joining of dissimilar alloys. Two of the key elements of the IFW process consist of friction between the mating workpieces (thereby heating the interface) and energy losses in the mechanical system per se. Methods to quantify the coefficient of friction and overall machine efficiency will be described. Second, methods to quantify transient flow behavior and the kinetics of the dissolution of gamma prime will be described. These techniques include special methods to investigate the interaction of dynamic microstructural changes and plastic flow. Last, the selection of process parameters for joining superalloys with different solvus temperatures/plastic-flow responses will be addressed. One particular method to reduce non-uniform metal flow, which involves local preheating, will be highlighted.

Bio

Dr. Lee Semiatin is Senior Scientist (ST), Materials Processing/Processing Science in the Air Force Research Laboratory, Materials and Manufacturing Directorate.  He received a BES in Mechanics from Johns Hopkins University and MS and PhD degrees in Metallurgy and Materials Science from Carnegie Mellon University.

Dr. Semiatin worked at Battelle Memorial Institute from 1978 to 1991.  Here, he conducted and directed programs for a wide range of government and industry clients.  A large portion of his government-sponsored work was for the Air Force Materials Laboratory and Air Force Office of Scientific Research (AFOSR).  This included basic studies of the workability of difficult-to-process aerospace alloys, the fundamentals of material behavior during deformation processing, and various National Aerospace Plane (NASP) - related programs.  Both the government as well as industrial programs involved a major component of technology transfer and thus working with a wide range of manufacturing companies.

In June 1991, Dr. Semiatin joined the Materials and Manufacturing Directorate as Senior Scientist for Materials Processing/Processing Science.  Under his direction, R&D has been conducted in four major areas:  advanced metallic, intermetallic, and nanocrystalline alloys; conventional titanium, nickel, and aluminum alloys; novel processes; and advanced modeling tools for the prediction of microstructure, texture, and damage evolution during deformation and solidification processing.  The integration of various modeling, characterization, and input-data tools that underlie ICMSE form a key part of current research. These efforts have led to the development of various new forging, extrusion, and rapid heat treatment processes - some of which are utilized on a production basis.  In addition, he consults regularly with a number of manufacturing vendors on material-processing problems which impact Air Force systems.

Dr. Semiatin has authored/co-authored over 400 journal papers in the area of materials processing. He has also written/edited 18 books/handbooks/conference proceedings, 27 limited distribution reports, and holds 9 patents.