Behaviour of fatigue short cracks in a medium carbon steel subjected to reversed torsion

The results of investigations into fatigue short cracks behaviour in a medium carbon steel under reversed torsional loading are presented. Characteristic features of surface crack initiation and crack growth were established on the basis of replication method and electron-optical observations. The plots of crack length, crack growth rate, crack population and crack length distribution versus cycle ratio have been hereby analysed. Relations between crack growth and microstructural features in the test pieces under investigations were enhanced.