High-pressure phase transformations and lattice distortions in industrial AISI 1070 steel: Insights from Debye-Scherrer ring integration

Abstract

In this study, the behavior of the industrially prominent AISI 1070 pearlitic steel under pressures up to 35 GPa was meticulously explored. Leveraging the 1D integration patterns from the Debye-Scherrer rings, we introduced a groundbreaking method to quantify dislocation densities, providing a novel lens to understand lattice distortions in such widely-used steels. At 5 GPa, the decomposition of cementite became evident, corroborated by changes in lattice parameters and dislocation densities. As the pressure neared to 10 GPa, the emergence of Hägg carbide was observed. The hallmark discovery was the phase transition from BCC to HCP around 20 GPa. This transformation bore witness to further distortions in the HCP structure with mounting pressures. Finally, molecular dynamic simulations revealed a mostly BCC to HCP transformation via an intermediary FCC phase at crystalline defects, elucidating observed orientations and phase transformation pathways.