Temperature, microstructure and mechanical response during shear-band formation in different metallic materials

Abstract
Adiabatic shear banding was investigated in low carbon steels, a nickel-base superalloy Inconel 718. Tests were performed using cylindrical as well as flat hat-shaped specimens in a Split-Hopkinson-Pressure-Bar setup. The flat specimen allows the in situ measurement of the temperature field by means of a fast infrared detector array simultaneously with the mechanical response of the specimen. Two types of arrays (InSb and InGaAs) were used in the localization and postlocalization phase, respectively, where the temperatures lie in different ranges. Special interest is given on the development of the localization process from the early stage up to well-developed bands and/or failure The microstructural changes were investigated in these stages using optical microscopy, SEM and TEM. The summarized result of all observations is that the shear bands ("white" bands in steel and similar but much thinner bands in lnconel 718) were formed during the postlocalization phase by friction processes obviously.