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DH36 marine steel chemical composition design

In order to ensure the high strength, low temperature toughness, good welding performance and other requirements of high-grade marine steel plates, combined with the role and harm of each element, according to the GB712-2011 standard, the high-strength hull structural steel DH36 (thickness 8.0~18.0mm) Chemical composition design.

Sulfur affects the impact toughness and ductile-brittle transition temperature of DH36 marine steel. Sulfide inclusions have a great influence on the properties of DH36 marine steel in different directions. Phosphorus mainly affects the shaping of DH36 marine steel. The development trend of modern steel is to reduce the content of these two harmful elements as much as possible, and to control the number, shape, size and distribution of sulfide inclusions. DH36 marine steel. Reducing the sulfur content can also have a good effect on the susceptibility to hydrogen sulfide stress corrosion cracking of DH36 marine steel.

The strength loss caused by the reduction of carbon content in DH36 marine steel can be compensated by adding ferroniobium, grain refinement and precipitation strengthening, because niobium is a strong carbon-nitrogen compound forming element, which can play a strengthening role. 0.01% niobium, DH36 marine steel can increase the strength by 30~50MPa.

After comprehensive consideration, it is determined that the chemical composition of DH36 marine steel adopts the design scheme of low carbon + high manganese + niobium microalloy.