Fracture behavior of 4340 steel under mode III loading

Abstract An experimental investigation was conducted to examine how the upper stress intensity factor in parallel shear K IIIQ (similar to K IQ for Mode I) is affected by increasing the tensile strength of a material. Round notched and precracked bar specimens, fabricated from 4340 steel were used for the investigation. Based on results from four different heat-treatments of this steel it was found that the stress intensity factor K IIIQ increases as the tensile strength increases. Values of K IIIQ obtained for high strength 4340 steel are in agreement with those found by other investigators.