抄録
The reversed torsion and rotating bending tests were carried out on the tufftrided steel specimens to investigate the influence of type of loading on fatigue properties. The changes in the fatigue limit, the hardness distribution, and the microstructure were examined.
The results obtained are as follows: -
(1) The fatigue limit under the reversed torsion increased after tufftriding by a factor of about 1.8, which was nearly the same as that obtained under the rotating bending.
(2) The rise of hardness distribution with stress amplitudes and the precipitation of nitrides along slip lines in the specimen fractured by the reversed torsion, were similar to those observed under the rotating bending.
(3) It appeared that the increase in hardness with stress cycles almost reached its upper limit within 10% of the total life, and then the precipitation of nitrides started to follow, though it was practically over in its early stage.
