Work rolls are core load-bearing components for workpiece shaping in steel rolling mills, and their service life directly impacts production efficiency, product quality, and operational costs. Significant differences exist in the service life extension strategies for work rolls between hot and cold rolling, stemming from fundamental variations in their operating environments. These differences lead to distinct failure mechanisms and ultimately shape a comprehensive technical framework encompassing material selection, process control, and maintenance. Below is a systematic analysis of the core differences in work roll life extension under these two scenarios.

First, there are fundamental differences in failure mechanisms and core control priorities. Hot rolling work rolls operate under harsh conditions, directly contacting workpieces at 800–1200°C and sustaining thermal cycling effects from alternating water cooling and high temperatures, which easily induce thermal fatigue. Coupled with abrasive wear caused by the scouring of oxide scale on the workpiece surface, their primary failure modes include thermal crack propagation, surface wear, and thermal fatigue-induced spalling on the roll surface. Consequently, precise temperature control is critical to extending their service life—industrial practice requires stabilizing the roll surface temperature at 55–65°C to prevent excessive thermal stress damage from rapid thermal cycling.

In contrast, cold rolling work rolls operate under vastly different conditions: while the temperature is low (close to room temperature), they endure extremely high unit rolling pressure, with stringent requirements for workpiece surface precision and roughness. Their main failure modes include surface wear, fatigue spalling from high-pressure cyclic stress, and scratches caused by embedded foreign objects. Accordingly, the core control priority lies in the precise regulation of rolling force and strip shape rather than temperature. The key is to avoid local stress concentration through process optimization, thereby preventing fatigue failure or roll surface defects and ensuring both workpiece quality and roll life stability.

Second, material selection and process optimization priorities differ distinctly. For hot rolling, high-speed steel (HSS) is preferred due to its excellent high-temperature stability, heat resistance, and wear resistance—its service life is 2–4 times longer than that of high-chromium cast iron rolls under the same conditions. Supporting process optimizations include hot rolling-specific lubrication (reducing the roll-workpiece friction coefficient by 3–5%), uniform cooling, and roll shifting, which effectively mitigate thermal damage and uneven wear. For cold rolling, high-carbon chromium steel serves as the base material; tungsten carbide (WC) coated rolls (with a service life 40 times longer than traditional chrome-plated rolls) are used in high-end precision applications (e.g., lithium battery pole piece rolling, high-precision thin plate rolling). Process optimization here focuses on precise rolling force control, improved emulsion lubrication and cooling, and stable rolling speed to avoid stress concentration and fatigue damage.

Third, maintenance and repair logics vary significantly. Hot rolling work rolls have a short grinding cycle (typically 50 km per cycle) and a low repair threshold, allowing multiple repairs and reuses via surfacing or laser cladding. Daily maintenance focuses on real-time monitoring of thermal crack initiation and propagation through non-destructive testing to prevent sudden failure from excessive crack depth. In contrast, cold rolling work rolls demand extremely high grinding precision (Ra 0.05–0.1 μm per industrial standards); even minor scratches can render the entire roll scrap due to adverse impacts on workpiece quality. As a result, their maintenance relies more heavily on full-cycle preventive measures combined with high-precision repair techniques (e.g., laser cladding) to minimize unplanned scrapping and ensure rolling precision and stability.