Tensile and fatigue behaviors of additively manufactured AlSi10Mg: Effect of solutionizing and aging heat treatments

Abstract

The effects of various heat treatments on the microstructure and mechanical properties of laser beam powder bed fused AlSi10Mg were investigated. Specimens were solutionized at three different temperatures of 425 C, 475 C, and 525 C followed by natural aging (T4) prior to microstructural and mechanical characterization. In addition, the effect of aging was studied by artificially aging (i.e., T7) some of the solutionized specimens at 165 C. Solutionizing at all temperatures was observed to fully dissolve the additive manufacturing (AM) induced dendritic microstructure, leaving bulky Si and needle-shaped β-AlFeSi precipitates in the grain interiors and boundaries. Tensile results revealed that T4 specimens exhibited more ductility, while T7 specimens showed substantially higher strengths with slightly reduced ductility. Interestingly, no significant effect of heat treatment on strain-life fatigue behavior was observed. Fractography found the Si particles to be responsible for tensile fracture, while AM volumetric defects were the main initiators of fatigue cracks.aluminum, fatigue, laser beam powder bed fusion (LB-PBF/L-PBF), microstructure, tensile Highlights• Effect of heat treatments on tensile and fatigue behavior of L-PBF AlSi10Mg studied.• T7 treatment led to higher tensile strengths than T4, but similar fatigue lives.• Tensile failure initiated from Si-particle fracture or debonding from matrix.• Fatigue life was affected by the size of crack initiators, that is, volumetric defects. | INTRODUCTIONAluminum alloys are commonly used in various industries because of their superior strength/stiffness to weight ratio compared to other alloys. 1,2 Among various Al alloys, AlSi10Mg as a cast alloy 2 has historically been used to fabricate complex/thin-walled geometries. Recently, processing AlSi10Mg through additive manufacturing (AM) has shown to be very promising as intricate, lightweight parts can be manufactured without

Absorbing capabilities of additively manufactured lattice structure specimens for crash applications: Damage tolerant design and simulations

“…The microstructure and defectivity of AM components are different from those of parts produced through traditional processes, like casting or machining, [1][2][3][4][5][6] with implications on the structural integrity that cannot be ignored for a safe design. For example, many experimental results have confirmed that the fine microstructure resulting from repeated fusions in as-built Selective Laser Melting (SLM) or Electron Beam Melting (EBM) processes ensures a tensile strength close to that of parts produced with traditional manufacturing processes, [7][8][9] with, on the other hand, a lower ductility. [10][11][12] Similarly, the fatigue life of AM parts tends to be lower than that of traditionally built (TB) components, mainly due to the high surface roughness, [13][14][15] residual stresses, 16,17 and the formation of large defects during the manufacturing process.…”