The Effect of Microstructure on the Spall Strength and Damage of 1045 Steel

The effect of microstructure on the shock response of 1045 steel is investigated via plate impact experiments and post-mortem characterization. Three unique microstructures are explored: ferrite-pearlite, martensite, and ferrite with spheroidal cementite (i.e. spheroidized). Two spall recovery experiments, at approximate peak pressures of 3.2 and 3.5 GPa, are conducted to assess the Hugoniot elastic limit (HEL), spall strength, and damage morphology of the various microstructures. The ferrite-pearlite and martensite microstructures exhibit continuous yielding at both quasi-static and dynamic rates, while the spheroidized condition displays discontinuous yielding. The spall strength of ferrite-pearlite is consistently lower than the spheroidized microstructure, and martensite exhibits the highest spall strength of the three microstructures. The resultant dynamic properties are discussed in the context of interphase boundary character, second phase morphology, and grain boundary energy.