The addition of Cu and P to 05CuPCrNi weathering steel is mainly to improve the corrosion resistance and solid solution strengthen ferrite.
1. Cu is the most important and most commonly used alloy element to improve atmospheric corrosion resistance. The addition of Cu to steel can form a dense copper oxide layer between the corrosion layer of steel and the copper-enriched layer, thereby slowing down and inhibiting The medium continues to corrode into the steel plate.
2. When the Cu content is greater than 0.15%, its resistance to atmospheric corrosion is slowly improved. P is an effective element for improving atmospheric corrosion resistance among alloy elements. It is an anode depolarizing agent. In electrolyte solution, it can accelerate the uniform dissolution of steel and the oxidation rate of iron, and help to form a uniform rust layer on the surface of steel. , And the boundary with the inner rust layer is obvious, thereby improving the corrosion performance of steel.
3. Cu in steel is controlled at 0.25% -0.35% and P lower limit is controlled at 0.07% -0.10%, which can meet the requirements of atmospheric corrosion resistance.Cr is also one of the alloying elements to improve the atmospheric corrosion resistance of low alloy steels, but generally it has a significant effect when it is combined with Cu. Cr has a low corrosion potential and is an element with a tendency to passivate. It promotes the formation of a densely oxidized passivation film on the surface of steel in the atmosphere, thereby improving the corrosion resistance of steel.
4. The content of Cr is controlled between 0.30% and 0.45% during atmospheric corrosion. Ni is also one of the effective alloying elements resistant to atmospheric corrosion. When the Ni content is ≤1% and Cu is contained in the steel, the effect of improving the corrosion resistance is not obvious. However, an alloy phase can be formed with a content ratio of 1: 3 of Ni and Cu. Therefore, controlling the Ni content of the steel containing 0.3% Cu to more than 0.1% can prevent it from cracking during hot rolling.
