Isothermal metal working (ISR) using resistance heating of the metal being worked is a new process developed by the Solar Division of International Harvester. The process is unique and can be used effectively to roll structural as well as special shapes from various alloys including titanium, stainless steel, and superalloys. Sheet or plate stock can be rolled into Z-section stiffeners and channels with square external corners and internal fillets. Bar stock can be rolled into “I” and “T” sections in one-or two-roll passes. Airfoils for gas turbine blades and vanes can be formed with rolls profiled with the contour shapes desired.
The general characteristics of the processes are described. These include: high metal recovery (better than 90%); fine surface finish (16 rms); freedom from surface contamination; major thickness reductions per pass (better than 80%); control of microstructure; and very low energy consumption in processing. These characteristics result in major cost reductions when compared with the existing methods of manufacture.