The question on initial under surface metal destruction zone formation mechanism is still open when, i.e. forming initial smooth facet on one of the crystallographic planes it takes place as it was specified above in titanic alloys. The best tool to answer these questions today is the AE method which to some extent traces down the above-stated mechanisms. As formed surface of a crack is increasing her power can be insufficient to supply gas environment needed for next or adjacent zones to the crack deliver this gas environment volumes in sufficient quantity. As the fact that fatigue crack in metal is being formed immediately after fixing an αcr angle was not directly proved recently, the question is about αcr role in formation of fatigue crack under surface and what processes are responsible thus for the αcr angle formation. This would give the chance to deduce the model of αcr angle formation. Thereby experimental studies of specially made samples from a titanic alloy on registration of crack formation moment under surface by means of αcr were carried out.