G. Pluvinage et A. Lanvin, STRETCH ZONE GEOMETRICAL MEASUREMENT, A PARTICULAR WAY TO MEASURE FRACTURE-TOUGHNESS, Fatigue & fracture of engineering materials & structures, 16(9), 1993, pp. 955-972
Stretch zone geometry (height and length) has been measured using five
methods (Transmission Electron Microscopy, Retrodiffused Electron Mic
roscopy, Nickel Plating, Roughness Measurement, Ondulation Method). Ex
perimental investigations show that the major difficulty of these meas
urements is the great scatter of experimental results. However, it is
seen that Transmission Electron Microscopy and Nickel Plating give suf
ficiently accurate results. By using these different methods, we have
found a linear relationship between stretch zone geometry and the clas
sical fracture toughness parameter J(k). Rolling direction, grain size
, loading rate, yield stress and the material texture are the influent
ial parameters determining the stretch zone geometry.