Low‐Cycle Fatigue and Modeling of Crack‐Tip Plasticity of an Additive‐Manufactured AlSi10Mg Alloy Submitted to Stress Relief and Direct Aging

This study explores the impact of build orientation and heat treatment on the low‐cycle fatigue (LCF) behavior of AlSi10Mg components produced using powder bed fusion with a laser beam (PBF‐LB) process. Specimens were fabricated in two orientations (0° and 45°) and then underwent two heat treatments: direct aging at 170°C for 2 h (A170) and stress relief at 300°C for 2 h (SR300). LCF tests were performed with stress ratios of R = −1 and R = 0.1, and strain amplitudes of Δ ε = 0.50% and Δ ε = 0.75%. Stress relaxation was observed in all specimens. The specimens treated with SR300 withstood 1000 cycles, whereas those treated with A170 withstood fewer cycles. KAM analysis revealed a concentration of dislocations around the microcracks. The LCF results are important for a strain‐based analysis of fatigue failure, but also for the modeling of elastic–plastic behavior. However, the application to fatigue crack growth (FCG) simulation showed that crack tip plastic strains were much higher than the LCF strain ranges. The LCF results are therefore extrapolated with an unknown impact on the accuracy. In addition, the dominance of cyclic plastic deformation as a damage mechanism responsible for FCG must be checked by comparing the size of the reversed plastic zone with the grain size.