Analysis of geometric features of quasi-brittle profiles of iron fractures with various levels of wavelet filtration in relation to the grain size of the ferritic structure

In this paper a relationship between metal structures described by equivalent grain size D and the average distance between local maximum and minimum points (〈LMMD〉-Local Maximum Minimum Distance) of fracture profiles for brittle fractures of commercially pure iron (99.65% Fe) samples is examined. The ferrite grain size was varied by cold upsetting and recrystallization annealing of the specimens. Impact loads, at liquid nitrogen temperature (Charpy V test), were used to break the samples. Fracture profiles were recorded using a contact profilometer. The profiles were subjected to wavelet filtration and a linear dependence 〈LMMD〉 = f(D) was revealed, and observed irrespective of the filtration level range of 2-7. Profiles were examined at low-level frequency wavelet approximations of raw profiles and with high-level frequencies to obtain details of these same profiles.