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The cyclic material behavior is investigated, by strain-controlled testing, of 8 mm thick sheet metal specimens and butt joints, manufactured by manual gas metal arc welding (GMAW). The materials used in this investigation are the high-strength structural steels S960QL, S960M and S1100QL. Trilinear strain-life curves and cyclic stress-strain curves have been derived for the base material and the as-welded state of each steel grade. Due to the cyclic softening in combination with a high load level at the initial load cycle, the cyclic stress-strain curve cannot be applied directly for a fatigue assessment of welded structures. Therefore, the transient effects have been analyzed in order to describe the time-variant material behavior in a more detailed manner. This should be the basis for the enhancement of the fatigue life estimation.

Additive manufacturing offers new options for lightweight design for safety parts under cyclic loading conditions. In order to utilize all advantages and exploit the full potential of additive manufactured parts, the main impact factors on the cyclic material behavior not only have to be identified and quantified but also prepared for the numerical fatigue assessment. This means in case of the AlSi10Mg aluminum alloy to consider influences related to the exposure strategy, heat treatment, microstructure, support structures and the surface conditions, as well as the influence of the load history and finally the interaction of these influences in order to perform a high quality fatigue assessment. Due to these reasons, and with respect to the numerical effort, the cyclic material behavior of additively manufactured AlSi10Mg produced by selective laser melting will be discussed.