Development and validation of a processing map for Aermet100 steel

Using the flow stress data obtained from the compression tests in the temperature ranges of 800-1200 degrees C and at strain rate ranges of 0.01-50 s(-1), the processing map of Aermet100 steel was developed based on a simple instability condition applicable to a general flow stress versus strain rate curve at any strain and temperature. Deformation mechanisms in the stable and unstable regimes were verified with the microstructure observations. The optimum hot processing windows of Aermet100 steel are at temperature ranges of 1025-1200 degrees C and at strain rate ranges of 0.03-15 s(-1), in which dynamic recrystallization occurs with a peak efficiency of power dissipation of 38%. The instability regimes I and II occur at low temperature ranges of 800-975 degrees C, and at strain rate ranges of 0.1-6 s(-1) and 4.5-33 s(-1), respectively. While the instability regime III occurs at high temperature ranges of 950-1200 degrees C and at high strain rate ranges of 15-50 s(-1). These instability regimes, whose microstructural manifestations such as cracks, shear bands and twin kink bands are detrimental to the mechanical properties of components, need to be avoided during hot processing of Aermet100 steel. (C) 2009 Elsevier B.V. All rights reserved.