With increasing size of the components, with geometric similarity maintained, the effective stress concentration factor increases, approaching the theoretical one. The scale makes itself felt the more, the larger the stress concentration factor and the greater the strength of the material is. It was noted in [i] that for large shafts with stress raisers in the form of fillets the endurance limit of shafts with I00 mm diameter or more is lower when the shafts are made of alloy steels than when they are made of carbon steel with the same diameter.