THE USE OF CHEVRON-NOTCHED SPECIMENS FOR FRACTURE-TOUGHNESS DETERMINATION OF BEARING STEELS

The use of three-point-bending of chevron notched specimens for plane strain fracture toughness determination was studied on two bearing ste els with various levels of tempering. For specimen- and notch geometry used the load-time (displacement) curves were presented and fracture behaviour was explained on the basis of fractographic observations. Th e aproximative procedure based on Bluhm's slice model was proposed for calculation of stress intensity factor, K(ICV), and the validity of t he model mentioned for these purposes was supported experimentally. Ve ry good agreement of fracture toughness data obtained on chevron notch ed specimens, K(ICV), was stated when compared with fracture toughness data, K(IC), measured by means of standard specimens with cyclic prec racking.