The results show that tempering temperature has obvious effect on the quantity and morphology of carbides in 30cr13nb0.1 steel, which indirectly affects the corrosion resistance of steel. The figure shows the potentiodynamic polarization curves of 30cr13nb0.1 steel quenched at 1020 ℃ and tempered at different temperatures in 3.5% NaCl aqueous solution.
It can be seen from the figure that the polarization curve of 30cr13nb0.1 steel tempered at 250 and 450 ℃ shifts obviously to the left, and the passivation current density increases, which indicates that the corrosion resistance of the steel tempered at 250 and 450 ℃ is lower than that tempered at 350 ℃. The results show that the corrosion resistance of the steel increases obviously at 450 ℃. The steel tempered at 250 ℃ and 450 ℃ has obvious passivation region.
The electrochemical parameters obtained by fitting the polarization curve. The self corrosion potential (ECOR (V / SCE)) of 30cr13nb0.1 steel tempered at 350 ℃ was significantly higher than that of steel tempered at 250 ℃ and 450 ℃, and the maximum pitting potential (V / SCE) was 0.140v. The self-corrosion potential and pitting potential are important parameters to reflect the pitting corrosion resistance of materials. The steel tempered at 350 ℃ has the highest self-corrosion potential and the largest pitting corrosion potential, so the pitting corrosion resistance is the best.