Cryogenic austenitic high-manganese steel having excellent shape, and manufacturing method therefor

Abstract

The cryogenic austenitic high-manganese steel having an excellent shape, according to one aspect of the present invention, comprises 0.2-0.5 wt% of C, 23-28 wt% of Mn, 0.05-0.5 wt% of Si, 1 wt% or less (but not 0 wt%) of Cu, 0.03 wt% or less of P, 0.005 wt% or less of S, 0.5 wt% or less of Al, 2.5-4.5 wt% of Cr, and 0.0005-0.01 wt% of B, with the remainder being Fe and other unavoidable impurities, and also comprises at least 95 area% of austenite as a microstructure, wherein the Charpy impact toughness at -196 DEG C is least 30 J (based on a thickness of 5 mm), and the maximum difference in height between a crest and a trough formed within an area of 2 m along the direction of rolling may be at most 10 mm.

Description

technical field [0001] The present invention relates to an austenitic high manganese steel material and a manufacturing method thereof, more specifically to an austenitic high manganese steel material for ultra-low temperature with excellent ultra-low temperature toughness and excellent shape and a manufacturing method thereof. Background technique [0002] For austenitic high-manganese steel, because the contents of manganese (Mn) and carbon (C) that improve the stability of austenite are adjusted, the austenite is also stable at room temperature or ultra-low temperature, and thus has high toughness. As LNG Materials for ultra-low temperature structures such as storage tanks and LNG transfer tanks have particularly suitable physical properties. [0003] However, high manganese (Mn) steels have high deformation resistance at high temperatures, and especially in the case of thin plate materials, it is difficult to ensure a uniform shape in the longitudinal direction depending...

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Problems solved by technology

[0003] However, high manganese (Mn) steels have high deformation resistance at high temperatures, and especially in the case of thin plate materials, it is difficult to ensure a uniform shape along the length direction depending on the rolling pass, reduction rate, etc.

If the shape of the hot-rolled material is poor, the safety of cooling will be reduced, which may cause equipment damage during transportation and other processes, etc.

In addition, if the shape of the hot-rolled material is poor along the length direction, subsequent operations such as shape correction operations are required, which is not preferable in terms of economy and productivity

Furthermore, even if further shape correction operations are performed after cooling, there are technical limitations in ensuring a uniform shape

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