Experimental investigation of adiabatic shear band formation in steels

Abstract
Experiments were made to study the process of adiabatic shear banding in various low carbon steels. The shear bands were formed using cylindrical hat-shaped specimens as well as specimens of prismatic shape in a Split-Hopkinson-Pressure-Bar setup. The latter type of specimen allows the in situ measurement of the temperature field by means of a fast infrared detector array. The microstructure was investigated by metallography, TEM, SEM and X-ray diffraction . Most interesting are the results of the post localization phase, which begins after a shear band is developed completely. In this phase a considerable growth of the width and a change of the microstructure of the band occur, carbides become dissolved and a rapid temperature increase is found. The measured peak temperature, which depends on the duration of this phase, is sufficient for a phase transformation to martensite via austenite in the used steels, which is confirmed by X-ray diffraction.