Heat treatment strategies for improving fracture toughness of high‑chromium white cast iron grinding media: an integrated mechanistic review

High-chromium white cast irons (HCWCIs) combine hard M7C3‑type eutectic carbides in a metallic structure, making them the material of choice for grinding balls, mill liners and other abrasion‑resistant components. Their weakness is not due to hardness but to fracture toughness: under the repeated impacts typical of comminution circuits, brittle carbide cracking and spalling govern failure. This review synthesizes the literature on how heat treatment involving destabilization (austenitizing), quenching followed by tempering and multi-stage or cyclic variables governs the balance between hardness, wear resistance and toughness in HCWCI grinding media and how these treatments interact with minor additions of alloying (Ti, B, Nb, V, and Mo) and with compositional variation within a nominal grade. Beyond summarizing individual studies, an integrated processing–microstructure–property framework is proposed to connect heat‑treatment parameters to fracture toughness through secondary carbide precipitation, matrix transformation, residual stress and carbide/matrix crack behavior, and a fracture mechanics perspective is used to interpret why heat‑treatment effects on toughness are carbide- and orientation-dependent. A comparison of four destabilization temperature studies, which differ in alloy system and in which properties each measured, nonetheless shows a consistent qualitative pattern: matrix hardness, impact toughness and wear resistance respond in opposing, non monotonic ways to the same processing variable, so that no single schedule optimizes all three simultaneously. Quantitative data compiled from multiple peer‑reviewed sources, with each table’s specific source stated explicitly, are presented in tables and figures, and remaining research gaps—including limited use of CALPHAD‑based kinetic modeling specific to HCWCI grinding media—are identified.