Abstract: Disclosed are a steel plate for a line pipe having excellent hydrogen induced crack resistance with a tensile strength of 450 MPa or more, and a preparation method thereof. According to the present invention, the steel plate for a line pipe, having excellent hydrogen induced crack resistance comprises: 0.03-0.05 wt % of carbon (C); 0.2-0.3 wt % of silicon (Si); 0.5-1.3 wt % of manganese (Mn); 0.010 wt % or less of phosphorus (P); 0.005 wt % or less of sulfur (S); 0.02-0.05 wt % of aluminum (Al); 0.2-0.5 wt % of nickel (Ni); 0.2-0.3 wt % of chromium (Cr); 0.03-0.05 wt % of niobium (Nb); 0.02-0.05 wt % of vanadium (V); 0.01-0.02 wt % of titanium (Ti); 0.001-0.004 wt % of calcium (Ca); and a balance of iron (Fe) and inevitable impurities, and has a tensile strength of 450 MPa or more.

Abstract: The present invention relates to a system and method for diagnosing cracking in a solidified shell in a mold, in which whether longitudinal cracking has occurred in the solidified shell can be diagnosed in real time by using a variation in temperature of the solidified shell in the mold during a continuous casting process. The system comprises: a plurality of temperature sensors arranged in a matrix form in a mold, wherein the plurality of temperature sensors are divided into a first group and a second group based on where cracking occurs; and a processor configured to: calculate a temperature difference between the temperature of the first group and the temperature of the second group from the temperatures detected by the plurality of temperature sensors; and determine, using the calculated temperature difference, whether cracking has occurred in a solidified shell discharged from the mold.

Abstract: The present invention relates to a method for predicting the degree of contamination of molten steel during ladle exchange. The method comprises: setting a casting quantity (Q) and a residual quantity of residual molten steel (Qrm); calculating, based upon the Qrm with proportional coefficients, a casting amount (Qplug) and a casting amount (Qpeak); determining preliminary degrees of contamination; and selecting the smaller of the preliminary degrees to obtain degrees of contamination.

Abstract: The present invention relates to an apparatus for turning steel products. The apparatus comprises a rotating shaft, a first turning plate, and a second turning plate. The first turning plate is fixedly mounted to the rotating shaft with a longitudinal axis of the first turning plate perpendicular to a longitudinal axis of the rotating shaft. The second turning plate is movably mounted to the rotating shaft with a longitudinal axis of the second turning plate perpendicular to a longitudinal axis of the rotating shaft.