On the use of a fictitious notch radius equal to 0.3 mm to design against fatigue welded joints made of wrought magnesium alloy AZ31

In the present investigation, a large number of fatigue data generated by testing welded joints of magnesium alloy AZ31 were post-processed based on the reference radius concept. The local stresses used to perform this systematic re-analysis were determined by setting the fictitious notch radius, r(f), invariably equal to 0.3 mm. According to this strategy, local stress-based S-N curves were then derived for load ratios, R, equal to -1, 0 and to 0.5. This post-processing exercise allowed us to demonstrate that a fictitious notch radius of 0.3 mm is successful in modelling the fatigue strength of weldments made of magnesium alloy AZ31. In particular, with r(f) = 0.3 mm, this type of welded joints is recommended to be designed against fatigue by using an S-N curve having endurable local stress range, Delta sigma(FAT), at N = 2 x 10(6) cycles to failure equal to 40 MPa and a negative inverse slope, k, equal to 3.