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Aims. We investigate statistical equilibrium of Cr in the atmospheres oflate-type stars to show whether the systematic abundance discrepancy between CrI and Cr II lines, as often encountered in the literature, is due to deviationsfrom LTE. Furthermore, we attempt to interpret the NLTE trend of [Cr/Fe] with[Fe/H] using chemical evolution models for the solar neighborhood. Methods.NLTE calculations are performed for the model of Cr atom, comprising 340 levelsand 6806 transitions in total. We make use of the quantum-mechanicalphotoionization cross-sections of Nahar (2009) and investigate sensitivity ofthe model to uncertain cross-sections for H I collisions. NLTE line formationis performed for the MAFAGS-ODF model atmospheres of the Sun and 10 metal-poorstars with -3.2 < [Fe/H] < -0.5, and abundances of Cr are derived by comparisonof the synthetic and observed flux spectra. Results. We achieve good ionizationequilibrium of Cr for the models with different stellar parameters, ifinelastic collisions with H I atoms are neglected. The solar NLTE abundancebased on Cr I lines is 5.74 dex with {\sigma} = 0.05 dex; it is \sim 0.1 higherthan the LTE abundance. For the metal-poor stars, the NLTE abundancecorrections to Cr I lines range from +0.3 to +0.5 dex. The resulting [Cr/Fe]ratio is roughly solar for the range of metallicities analyzed here, which isconsistent with current views on production of these iron peak elements insupernovae. Conclusions. The tendency of Cr to become deficient with respect toFe in metal-poor stars is an artifact due to neglect of NLTE effects in theline formation of Cr I, and it has no relation to peculiar physical conditionsin the Galactic ISM or deficiencies of nucleosynthesis theory.

Chromium: NLTE abundances in metal-poor stars and nucleosynthesis in the Galaxy