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The possibility of a pure Mode III crack growth is analyzed on thebackground of theoretical and experimental results achieved in the last 20 years. Unlikefor Modes I and II, there is no plausible micromechanistic model explaining a pureMode III crack growth in ductile metals. In order to realize “plain” Mode III fracturesurface, we propose a propagation of a series of pure Mode II cracks along the crackfront. Fractographic observations on crack initiation and propagation in a low alloysteel under cyclic torsion support such a model. The authors do not see any clearindication of a pure Mode III micromechanism in ductile metals till now.