Influence of local crystallographic orientation on short crack propagation in high cycle fatigue of 316LN steel

In this study, three dimensional finite element calculations taking into account cubic elasticity and crystalline plasticity are performed in order to quantify the influence of the crystallographic orientation on the development of the plasticity at the crack tip of microstructurally short cracks in 316L stainless steel. The case of a transgranular stage I crack that ‘propagates’ towards a grain oriented for multiple slip is considered. The values of the crack tip opening/sliding displacements are calculated for the crack located at different distances of the ‘multiple slip’ grain. Two multiple slip orientations are considered for this adjacent grain: a 〈1 1 1〉 orientation and a 〈1 1 ¯ 0〉 orientation. Calculations show that the opening/sliding displacement at the crack tip is higher (up to a factor 1.7) if the crack propagates towards a 〈1 1 ¯ 0〉 grain than towards a 〈1 1 1〉 grain. This could imply that propagation towards a 〈1 1 1〉 grain is more difficult than towards a 〈1 1 ¯ 0〉 grain.