Improvement Of The Fatigue Behaviour Of Additive Manufatured Scalmalloy By Using Surface Improvement Processes

The use of light metals such as Aluminum alloys has experienced a remarkable increase for the additive manufacturing (AM) industry, especially in aerospace. AM Scalmalloy®. (an Al-Mg-Sc alloy) shows outstanding behavior with much higher mechanical performance with respect to other alloys for powder bed fusion laser-based (PBF-LB) process like AlSi10Mg or AlSi7Mg. Recent studies have mainly focused on static loading, with minor attention to cyclic loading despite its vital importance in many applications. In this work, the fatigue performance of PBF-LB Scalmalloy was investigated considering the effects of surface treatments to identify the set of optimal post-processes. Shot peening with steel and glass shots, laser peening combined with C.A.S.E. (chemically assisted surface enhancement) treatments were initially selected. Blind hole drilling method has been applied to obtain depth residual stress profiles. Tensile and fatigue tests were also performed for each surface treatment. Steel Shot Peening + C.A.S.E. lead to significantly improvement in the fatigue life of the Al-Mg-Sc parts, reducing internal defects and roughness, thanks to the generation of a favorable residual stress field. Afterwards, the treatments were validated in an optimized AM demonstrator.