Alloying elements in S690Q

The chemical composition of S690Q mainly includes carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S) and other elements. Among them, carbon is the main element that affects the strength and toughness of steel; silicon and manganese help improve the toughness and welding performance of steel; phosphorus and sulfur are impurity elements, and their presence will reduce the toughness and corrosion resistance of steel. Therefore, the composition control of S690Q is very critical.

In addition, S690Q also contains a certain amount of alloy elements, such as nickel (Ni), chromium (Cr), etc. These elements can improve the corrosion resistance and fatigue resistance of steel. Specific alloying element contents may include: phosphorus (P) ≤ 0.025%, sulfur (S) ≤ 0.020%, niobium (Nb) ≤ 0.11%, vanadium (V) ≤ 0.12%, titanium (Ti) ≤ 0.20%, chromium ( Cr) ≤ 1.00%, Nickel (Ni) ≤ 0.80%, Copper (Cu) ≤ 0.80%, Nitrogen (N) ≤ 0.015%, Molybdenum (Mo) ≤ 0.30%, Boron (B) ≤ 0.004%, Aluminum (Al) ≥0.015%.

The presence of these elements makes the S690Q steel plate have high yield strength and tensile strength, as well as good toughness, welding performance and corrosion resistance.

The alloying elements in S690Q have a significant impact on the properties of the steel. Here’s a detailed explanation of how these alloying elements affect steel properties:

Nickel (Ni): Nickel is an important element that improves the corrosion resistance of steel. In S690Q, the presence of nickel helps enhance the steel's durability in humid or corrosive environments, reducing the risk of damage to the steel due to oxidation or corrosion.

Chromium (Cr): Chromium is also a key element in improving the corrosion resistance of steel. Like nickel, chromium increases steel's resistance to oxidation and corrosion, especially when exposed to high temperatures or moisture.

Niobium (Nb), vanadium (V), titanium (Ti): These elements are usually added to steel as micro-alloying elements to enhance the strength and toughness of steel by refining the grains and improving the precipitation strengthening effect of the steel. They help improve the welding properties and fatigue resistance of steel.

Copper (Cu): Copper also has a certain corrosion resistance role in steel, especially in preventing certain types of corrosion. At the same time, copper can also improve the strength and toughness of steel.

Molybdenum (Mo): The presence of molybdenum can improve the strength and toughness of steel, especially under high temperature conditions. In addition, it also helps improve the corrosion resistance of steel.

Nitrogen (N): Nitrogen is an effective strengthening element that can increase the strength and hardness of steel. In S690Q, the right amount of nitrogen helps achieve the high strength requirements of the steel.

Boron (B): Boron mainly plays the role of refining grains in steel, helping to improve the strength and toughness of steel.

To sum up, the alloy elements in S690Q work together through different mechanisms to make the steel have high strength, high toughness, good welding performance and excellent corrosion resistance. These performance characteristics make S690Q steel plates have broad application prospects in bridges, buildings, ships, marine engineering and other fields.