Properties of Q235NH steel after corrosion

By analyzing the corrosion morphology of Q235NH steel specimens after corrosion, and the tensile properties under normal and corrosion conditions, the following conclusions are drawn:

1) After Q235NH steel is corroded, a protective rust layer will be formed on its surface, which has a protective effect on the steel substrate. As the corrosion time increases, the adsorption force of the rust layer increases, which slows down the decline in the mechanical properties of the specimen.
2) As the corrosion time increases, the mechanical properties of Q235NH steel decrease, and the stress and strain curves after corrosion are lower than normal. The elastic modulus and elongation do not change significantly with the increase of corrosion time, but the yield strength and tensile strength , yield strength ratio and its reduction coefficient show a linear decrease trend with the increase of corrosion time, and the related linear degradation formula is established.
3) The parameters of the strengthening stage of the secondary plastic flow constitutive model are corrected, and the modified secondary plastic flow model obtained can well fit the stress-strain relationship of Q235NH steel before and after corrosion.