Editor's Note: A hypertext-enhanced version of this paper can be found on JOM's web site at www.tms.org/pubs/ journals/JOM/9901/ForbesJones-9901.html.This article provides an overview of structural changes that occur during the hot working of superalloys and provides insight into the use of precipitated particles and other thermomechanical factors to achieve desired structures. Examples will focus primarily on alloys 718 and 720, which are iron-nickel and nickel-based alloys, respectively. The availability of a second phase to control grain size is a characteristic of some iron-nickeland nickel-based superalloys that is not usually available to cobalt-based superalloys; processing with and without the use of a precipitated phase that influences microstructures will be illustrated by the use of these examples.
ABOUT THE AUTHORSRobin M. Forbes Jones earned his Ph.D. in metallurgy at Imperial College of Science and Technology, London University, in 1967. He is currently manager of long-range product/ process R&D for Allvac.Laurence A. Jackman earned his Ph.D. in metallurgy at Rensselaer Polytechnic Institute in 1967. He is currently chief materials scientist at Allvac. Dr. Jackman is also a member of TMS.For more information, contact R.M. Forbes Jones,