Effect of carbon and silicon on DH36 steel

·Carbon
The key performance index of DH36 steel plate is the low temperature impact toughness of DH36 steel plate, which requires the impact energy at -20°C to be greater than or equal to 34J.

Generally speaking, the lower the carbon content, the better the low-temperature impact toughness of the steel plate, but when the carbon content is low to a certain extent, the oxygen content at the end of the converter will inevitably increase significantly, resulting in an increase in inclusions in DH36 steel plate, which in turn will reduce the low temperature impact toughness of the steel. At the same time, carbon acts as an interstitial solid solution element in DH36 steel plate, which can cause strong distortion of the crystal lattice, which has a great influence on the strength of DH36 steel. Too low carbon content will greatly reduce the strength of DH36 steel.

In order to prevent the overoxidation of DH36 molten steel during the smelting process and ensure that the strength of DH36 steel meets the standard requirements, the middle and lower limits of carbon content are controlled, which is conducive to the fine-grain strengthening and precipitation strengthening of niobium, and the toughness and strength of DH36 steel are simultaneously improved. The lower carbon content is also conducive to maintaining excellent welding performance.

·Silicon
Silicon is almost completely dissolved in ferrite in DH36 steel. Silicon can significantly increase the yield strength and tensile strength of DH36 steel, but it will also reduce the elongation and impact toughness, and reduce the weldability of DH36 steel plate.