Mechanochemical effects have been investigated in the processes of corrosion of bent plates of unalloyed and high-alloy steel in aqueous solutions of sulfuric and hydrochloric acids. Special attention was paid to the strain sign effect discovered recently and caused by the existence of a surface stress in solids. The use of the weight method and the hydrogen method of corrosion control has yield well consistent results confirming the existence of the mechanochemical effect of the strain sign even under condition of the starting corrosion cracking. The domination of corrosion on the concave side gives evidence of the negative sign of surface stress at the steel/solution boundary, which can be explained by the formation of the electrical double layer.