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Effect of MnS on Chemical Composition of DH36 Steel

Although the S content in DH36 steel meets the requirement of the national standard for the sulfur content to be less than 0.025%, the impact energy fluctuates greatly. Many researchers believe that MnS is the main inclusion in DH36 steel, and its size and quantity significantly affect the mechanical properties of the steel, especially the impact toughness.

When the temperature of the solid-liquid two-phase region of DH36 steel is in the range of 1470-1510℃, the actual solubility product of MnS is smaller than the theoretical solubility product, indicating that in the entire temperature range during solidification, MnS cannot be precipitated in the liquid phase, but it is also It is found that the actual solubility product tends to approach the equilibrium solubility product gradually when the temperature gradually decreases, that is, when the temperature is close to the solidus temperature.

DH36 steel forms high-temperature ferrite and austenite at 1510℃and 1495℃, respectively. Due to the fast cooling rate of high-temperature ferrite and the small temperature range, after DH36 steel solidifies, there is a high probability that it will directly enter the austenite region. The depletion of its solute content in the high temperature ferrite region is negligible.