Development of Composition of Q235NH Weathering Steel

P is also the most effective element in Q235NH weathering steel to improve the atmospheric corrosion resistance. Generally, it is not used alone, but combined with Cu, Cr and other elements to achieve better results.

When the P content increases from 0.01% to 0.08%, the atmospheric corrosion resistance of Q235NH weathering steel is greatly improved, but when the P content exceeds 0.08%, the atmospheric corrosion resistance does not improve significantly, and excessive addition will reduce the corrosion resistance of Q235NH weathering steel. ductile plasticity.

Therefore design P<0.025%. When Cr and Cu elements are used together, the weather resistance of Q235NH weathering steel can be significantly improved, and the Cr content is specially designed to be 0.40%~0.50%.

S element has great harm to the atmospheric corrosion resistance of Q235NH weathering steel, so it is required that S<0.015% in Q235NH weathering steel.