Fatigue life of high-strength additively manufactured aluminium Al2139

Abstract The area of additively manufactured aluminium has so far been dominated by low-strength alloys such as AlSi10Mg even though several high-strength aluminium alloys have been developed in recent years. In this study, the fatigue life of the new additively manufactured high-strength aluminium alloy Al2139 was investigated and benchmarked against additively manufactured AlSi10Mg. The effect of geometrical notches and surface roughness on fatigue life was compared including roughness of down-skin areas. The Al2139 specimens showed superior fatigue strength in the machined condition, but AlSi10Mg had higher fatigue strength when comparing specimens with as-built surface. The latter results, although Al2139 had almost twice the tensile strength, showed that the difference in fatigue strength for specimens with as-built surface was mainly attributed to the rougher surface of the Al2139 specimens which had up to 4 times higher surface roughness for vertical areas and up to 10 times higher surface roughness in down-skin areas compared to AlSi10Mg specimens.