A new phenomenological strain hardening function is proposed to describe the strain hardening behavior of metallic materials. The function is based on a simplification of an earlier established self and latent hardening crystal plasticity approach. The proposed function contains only four parameters, which can be readily obtained using an efficient numerical technique by fitting the experimental curve. Several applications on different materials are presented and good agreements with the experimental counterparts were obtained. One great advantage of the proposed empirical function is that its parameters can be directly used in polycrystal viscoplastic modeling (VPSC approach) for crystal plasticity-based incremental strain hardening simulations. For the conversion of the parameters between the macroscopic scale and the grain-level, the Taylor factor was used, which was re-defined for polycrystals in the present work. The VPSC simulations also led to good reproduction of the experimental strain hardening behavior for all investigated cases, with rapid convergence.