Enhancing microstructural homogeneity and tensile isotropy in Cr–Ni–Mo–V steel via composite shear flow casting

Abstract

This study investigates the influence of composite shear flow casting (CSFC) in enhancing the microstructural homogeneity and tensile properties of Cr–Ni–Mo–V steel compared to conventional solidification (CS). In the as-cast state, CSFC significantly increased the equiaxed grain fraction from 9.7% to 56.3%, decreased the texture index from 12.81 to 4.68, and reduced the segregation of Nb, C, Mo, Cr, and V. Following post-forging annealing, CSFC samples exhibited a refined, equiaxed microstructure with grain sizes ranging from 3.78 to 5.72 µm, in contrast to the distinct banded structure observed in CS samples. Furthermore, CSFC enhanced yield strength through pronounced grain boundary strengthening (contributing 259 to 319 MPa) and promoted tensile isotropy by impeding crack propagation along columnar grain boundaries and banded interfaces, which were prevalent in CS samples and led to inconsistent ductility (9.3% to 14.5%). Consequently, CSFC samples achieved uniform elongation (11.4%–12.4%) across all directions, attributed to a homogeneous microstructure that effectively dispersed stress and suppressed localized crack growth, thereby simultaneously enhancing both strength and ductility.

Keywords

composite shear flow casting / Cr–Ni–Mo–V steel / microstructure / tensile properties / ductility mechanism

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