The influence of crystallographic texture on elastic and plastic constitutive response has seen extensive investigation in recent years. In contrast, the influence of anisotropy on the fracture of engineering materials remains less explored. In particular, the influence of anisotropy, both crystallographic and morphological, on the dynamic fracture behavior of materials remains largely unquantified. In this study, the quasi-static and dynamic fracture of 1080-steel has been studied as a function of microstructural morphological anisotropy. Previous research has shown how crystallographic anisotropy can control ductile damage evolution. In this study, the role of microstructural anisotropy, due to the presence of elongated MnS stringers, resident within a crystallographically isotropic eutectoid steel was investigated. The quasi-static and dynamic fracture response of a fully-pearlitic 1080 steel was found to be dominated by the heterogeneous nucleation of damage normal and orthogonal to the MnS stringers. Delamination between the matrix pearlitic microstructure and the MnS stringers was seen to lead to significantly lower quasi-static and dynamic tensile strains to failure during transverse loading compared to loading parallel to the stringer axis. The constitutive and damage behavior of a 1080 eutectoid steel as a function of loading direction, stress state, and temperature is discussed with reference to the influence of morphological anisotropy on void nucleation and growth.
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