Optimizing hot workability and controlling microstructures in difficult

Abstract

An improved hot forming method for metals, alloys and the like, and in particular, for difficult to process high strength and high temperature metals and alloys of particular use in aerospace applications, is described, which comprises the steps of generating flow stress data as a function of strain rate and temperature on samples of the material at predetermined strain within predetermined ranges of temperature and strain rate; determining from that data the strain rate sensitivity and power dissipation efficiency of the material within the ranges of temperature and strain rate represented by the generated data; selecting values of strain rate and corresponding temperature for a selected value of the dissipation efficiency for the material; and hot forming the material at the selected strain rate and temperature values to a predetermined shape. The improved method may be of particular application to forging, extrusion, rolling or other hot forming process appropriate for titanium, aluminum, nickel, cobalt, copper, iron, zirconium and their alloys. A processing map for hot forming each metal or alloy may be generated according to the methods taught.