Additively Manufactured Metallic Materials—Specifics of Their Fatigue Properties

Abstract

Additive manufacturing of metals has brought new challenges for the assessment of fatigue strength and service life, and for metal components necessitates standardization of both production and engineering procedures for calculating their fatigue life. The article provides an in-depth analysis of the specific characteristics that additive technology has brought to the cyclic properties of metal materials. For three selected materials—MS1, 316L, and AlSi10Mg—these specific characteristics are documented on the basis of cyclic tests performed under alternating axial loading and alternating torsion by the same testing machine. The cyclic tests are experimentally documented with S-N curves for these materials and compared for production by conventional metallurgy and additive technology. Comparison and analysis of the experimental results allow the summarization and partial quantification of the specific characteristics of additively manufactured metals that need to be considered in the computational evaluation of fatigue life, including anisotropy of mechanical properties as a result of the direction of layer addition, internal and surface defects, surface roughness as a result of balling, differences in slopes of S-N curves from normal, and shear stresses.