- The fatigue resistance of AM-SLM AlSi10Mg samples built in the Z direction after various heat treatments was investigated. Specimens were tested in the as-built (AB) condition, after stress relief (SR) treatment and after SR and hot isostatic pressing (HIP) at either 250 °C or 500 °C. The AB machined and polished specimens displayed the highest fatigue limit ( S f = 125 MPa, N f = 10 7 cycles). SR and HIP cycles decrease the yield strength, hardness and fatigue limit. The SR and HIP treatment at 500 °C resulted in the lowest fatigue resistance due to significant microstructural changes. A relation between the yield stress and fatigue resistance was established. Linear elastic fracture mechanics were employed for evaluating fracture surface morphology. Based on the results of fracture surface characterization, values of the critical stress intensity factor ( K cr ) for AM-SLM AlSi10Mg specimens after various heat treatments were estimated.