HOT-WORKING CHARACTERISTICS OF NICHROME AND THE DEVELOPMENT OF A PROCESSING MAP

A processing map for the hot working of nichrome has been developed on the basis of hot compression data in the temperature range 750-1200-degrees-C and strain-rate range 0.0003-100 s-1. The map exhibits a domain of dynamic recrystallization with a peak efficiency of 38% occurring at 1200-degrees-C and 0.1 s-1, which are the optimum parameters for the hot working of nichrome. At temperatures lower than 900-degrees-C and strain rates less than 0.001 s-1, the material exhibits grain boundary cracking. Flow instabilities manifesting in the form of mechanical twinning at lower temperatures (< 1050-degrees-C) and as inhomogeneous recrystallized bands at higher temperatures have been recorded in specimens deformed at strain rates greater than about 1 s-1.