Abstract: Austenite conditioning leading to refined final microstructures is now routinely practiced around the world. Initially developed for flat rolled strip and plate, its principles have been extended to the forging industry. Conditioned austenite can exhibit either “pancaked” austenite grains, or fine equiaxed austenite grains, depending on whether the deformation takes place below or above the recrystallization-stop temperature (T95). Since low temperature forging deformations are deleterious to die life, high temperature forging based on Recrystallization Controlled Forging(RCF) has been used in this study. RCF requires austenite grain boundary pinning by substoichiometric particles of TIN and repeated recrystallization during multi-pass deformation above T95. Following extensive grain refinement during forging, the steels underwent controlled cooling, leading to final microstructures of ferrite-pearlite, bainitic ferrite or auto-tempered martensite. UTS values from 760 -1450 MPa were obtained in the final forgings.
Authors: Aaron E Stein and Anthony J. DeArdo
Keywords: Recrystallized Controlled Forging, Titanium Nitride, Austenite Grain Refinement