h i g h l i g h t s Stress-strain behaviour of microstructure layers were determined experimentally. Constitutive relations for perlitie/ferrite, bainite and martensite were deduced. A simple model allows to calculate full stress-strain curve of composed QST rebar. Uniform corrosion leads to strong reduction of load-bearing capacity for QST rebars. Load-bearing capacity is not significantly reduced in case of pitting corrosion. g r a p h i c a l a b s t r a c t