Investigation of high‑temperature tensile damage behavior and fracture mechanisms in DC53 tool steel

To elucidate the high-temperature damage and fracture mechanisms of DC53 tool steel during cutter ring hot forming, high-temperature tensile tests were performed on notched specimens. Instead of a single condition, a range of temperatures (1000–1060 °C), strain rates (0.05–5 s⁻¹), and notch radii (2.5–30 mm) was investigated. The fracture morphologies and microstructures of the specimens were examined using optical microscopy and scanning electron microscopy. The results show that the peak tensile load of DC53 steel increases with decreasing temperature and increasing strain rate. Its ductility and fracture strain are enhanced with increasing temperature and strain rate. Under low stress triaxiality, DC53 steel exhibits pronounced brittleness. With increasing temperature and strain rate, the fracture mechanism gradually shifts from brittle to ductile. At low stress triaxiality, dynamic recrystallization is suppressed, resulting in coarse intergranular fracture features and a significant reduction in ductility. Voids preferentially nucleate at carbides, while their growth and coalescence are significantly inhibited under conditions of intensive dynamic recrystallization. Based on these findings, a high-temperature damage and fracture model for DC53 tool steel is proposed.