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On account of the ongoing trend towards lightweight construction, the use of dual-phase steels (DP steels) has gained high popularity. However, the underlying micromechanics, which give DP steel its prominent property of reaching high strengths while maintaining high formability, are also the cause of the difficulty in predicting springback after forming processes. The resulting geometrical change of a sheet metal part due to springback is mainly determined by the materials elastic properties and the residual stresses due to deformation. Therefore, the influence of the by now widely observed nonlinear elasticity has been considered in forming simulations and yielded significant improvement. However, an exact prediction is still not possible. Thus, to deepen the understanding of the elastic-plastic material behavior, the influence of another known property-altering phenomenon on the nonlinear elasticity of DP steel, the relaxation over time is analyzed. The results of the experimental relaxation tests show a slight but definitive influence on the elastic behavior of the investigated steels. The recorded unloading moduli are being furthermore used in a springback simulation to test their applicability and potential use. A final validation of the numerical results with an experimental plate bending test highlights the need for further investigation of the numerical adaptation of a relaxation dependent springback prognosis.