Abstract
The authors previously observed that the tufftriding treatment was effective to the improvement of fatigue limit of iron and steel. However, it is a complex task that the designer obtains the fatigue limit of tufftrided steel from the fatigue test.
In this paper, the prediction of fatigue limit was discussed from the viewpoints of the increase of hardness due to the tufftriding treatment and the cyclic stress and the existence of residual stress due to the tufftriding treatment which contributes to the improvement of fatigue limit. The following predicting equation was proposed.
σw·t=C1(h/a-h)σw·nt+(1+C2)σw·nt
where, σw·t: fatigue limit of tufftrided specimen
σw·nt: fatigue limit of non-tufftrided specimen
h: hardened depth
a: distance from the surface to the center of specimen
C1: a constant which indicates hardening due to cyclic stress
C2: a constant which indicates the degree of improvement of fatigue limit due to residual stress
The validity and the applicability of the equation was investigated by the experiment.
