Measurement techniques for determination of ductile crack initiation on Charpy specimens

In the engineering practice it is of importance to know the effect of loading rate on the material behaviour including the fracture mechanics properties. Depending on the material behaviour under a given loading condition, different fracture mechanics parameters should be determined. The critical values of these parameters are usually related to the onset of crack initiation which can be determined easier in the case of brittle fracture. But in the case of ductile fracture additional measurement techniques are required, This paper presents some possibilities to characterise the fracture resistance against ductile fracture using instrumented impact testing. The magnetic emission technique will be introduced as a potential measurement method for determining the onset of ductile crack propagation in magnetizable metals.