Very high cycle regime fatigue of thin walled tubes made from austenitic stainless steel

Abstract

ABSTRACT Fatigue life data of cold worked tubes (diameter 4 mm, wall thicknesses 0.25 and 0.30 mm) of an austenitic stainless steel, AISI 904 L, were measured in the regime ranging from 2 × 10 5 to 10 10 cycles to failure. The influence of the loading frequency was investigated as data were obtained in conventional rotating bending at 160 and 200 Hz and in ultrasonic axial loading at 20 kHz. Above 5 × 10 6 cycles the fatigue lifetimes found with both methods were comparable. The results show that the slope of the S–N curve significantly decreases beyond 10 8 cycles. Fracture surfaces were examined using scanning electron microscopy. Fatigue cracks initiate at the surface and no significant influence from frequency or from loading modes on fatigue crack initiation and growth is visible.