Variable amplitude fatigue crack growth at monotonic large scale yielding experiments on stainless steel 316L

• Variable amplitude monotonic LSY fatigue crack growth experiments were conducted.
• The local CTOD was controlled in situ in the experiments.
• The crack lengths were measured by the potential drop technique.
• The CTOD was able to characterize the fatigue crack tip load state.
• The fatigue crack growth rates at monotonic LSY were predicted by SSY fatigue data.

Fatigue crack growth in stainless steel 316L was investigated for two different variable amplitude block loads in the monotonic large scale yielding load range. The crack tip opening displacement, δ, was controlled in situ based on numerical computations on the coupling between the applied load, the crack length and δ. The average growth rates over the block sequences were determined from potential drop and visually measured crack lengths. The experimental growth rates were also predicted, based on small scale yielding fatigue crack growth data from closure free experiments, using a straight forward average procedure. The possibility to use small scale yielding material data was explained the by the large isotropic material hardening and closure free crack growth.