Fatigue resistance of austenitic stainless steel bolts under tension

The design of bolts made of carbon steel and stainless steel under fatigue loading is carried out according to EN 1993‐1‐9. However, the current regulations of the fatigue resistance of stainless steel bolts are based on investigations carried out for bolts made of carbon steel although the material properties of stainless steel are clearly different in terms of nonlinearity and strain hardening. Herewith, the question arises whether the design rules for carbon steel bolts are applicable to stainless steel bolts as the actual fatigue behaviour is almost unknown.

In order to close this gap of knowledge, experimental investigations into the fatigue behaviour of partially threaded bolts according to EN ISO 4014 made of austenitic stainless steel were carried out under tension with constant amplitude loading with either a constant stress ratio R or with a constant mean stress σ_m. The tests were statistically evaluated and S‐N curves could be determined.

The fatigue tests showed that a fatigue resistance of FAT class 50 according to EN 1993‐1‐9 can be achieved. Herewith, so far, it can be shown that a design according to FAT class 50 might be on the safe side for partially threaded bolts made of austenitic stainless steel.