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In order to investigate the crack path of materials containing a smallcrack under mixed mode loading, reversed torsion and combined push-pull/torsionfatigue tests were carried out on 0.47% carbon steel specimens containing an initialsmall crack. The initial small cracks were introduced by a preliminary push-pull fatiguetest using a specimen which contained an artificial small hole of 40μm diameter/depth.Firstly, the mechanism of fatigue crack growth under reversed torsion and combinedpush-pull torsion were investigated. Then, fatigue tests of push-pull followed byreversed torsion and reversed torsion followed by push-pull were carried out. Fatiguetests of combined push-pull/torsion followed by push-pull were also carried out toexamine the effect of crack geometry, such as branching and kinking, on cumulativefatigue damage. Different crack growth behaviours due to different loading modes andsequences complicatedly influence the fatigue crack path and eventully the cumulativefatigue damage. Thus, existing fatigue damage theories cannot be applied to the casespresented in this study. The crack like factory-roof morphology is locally made on thefracture surface of the specimen having a semi-elliptical crack under cyclic torsion.Torsional fatigue tests of circumferentially cracked specimens were carried out to investigatethe mechanism of mode III crack growth and formation of the factory-roof morphology. Thefactory-roof morphology in torsional fatigue of cracked specimen is formed by mode I crackbranching from small semi-elliptical cracks nucleated ahead of the initial crack tip by shear.