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

摘要

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/, 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, Δσ_(FAT), at N - 2 × 10~6 cycles to failure equal to 40 MPa and a negative inverse slope, k, equal to 3.