The invention discloses ultralow-temperature high
manganese steel and a manufacturing method of an ultralow-temperature high
manganese steel plate. The ultralow-temperature high
manganese steel comprises the following components in percentage by weight: 0.35-0.55% of C, 0.01-0.10% of Si, 20.00-30.00% of Mn, 0.01-0.10% of Al, less than or equal to 0.005% of P, less than or equal to 0.003% of S, 3.0-5.0% of Cr, 0.3-1.0% of Cu, 0.2-1.20% of Ni, less than or equal to 0.008% of N, less than or equal to 0.002% of O, less than or equal to 0.0002% of H and the balance of Fe and inevitable
impurity elements. The manufacturing method of the ultralow-temperature high manganese steel plate comprises the steps of molten iron pretreatment, K-OBM-S converter
smelting, LF refining,
continuous casting, annealing and coping, hot rolling, online
solution treatment and the like. According to the method, high steel purity, low
phosphorus and
sulfur content, small segregation of the
casting blank and the steel plate, good macrostructure of the
casting blank and no crack on the surface and in the
casting blank can be guaranteed, and the finished steel plate has the characteristics of low
yield ratio, high tensile strength, high ultralow-temperature
toughness, small
thermal expansion coefficient, good
fatigue resistance and the like; through the implementation of the invention, the manufacturing cost of the steel for the
liquefied natural gas storage tank can be reduced to 1 / 3 of that of 9% Ni steel in the prior art.