Dynamic Fracture Characteristics of High-Strength Steel

The absorbed impact energy KV and the dynamic fracture toughness KId of the low-alloyed steel OCHN3MFA were measured in the respective temperature ranges 〈–40, 90〉 and 〈–60, –20〉 °C. The values of impact energy in the range of 〈14.1, 21.3〉 J were obtained using Charpy V-notch samples after subtracting parasitic energies (friction in bearings, etc.). All these values corresponded to an extended transition region since the temperature –40 °C was still higher than the lower shelf impact-energy (shear lips present) and the temperature 90 °C was lower than the upper shelf (only 20 % of ductile morphology). Dynamic fracture toughness was determined using Charpy V‑notch samples with fatigue pre-cracks. The related KId-values were obtained in the range 〈55.8, 77.5〉 MPa.m1/2. They were found to be valid linear-elastic fracture toughness and were somewhat higher than the previously reported static KIc-values. The study revealed that OCHN3MFA steel has sufficient resistance to dynamic fracture, particularly at low temperatures.