Saving type duplex stainless steel and preparation method thereof

Abstract

Disclosed are a lean duplex stainless steel and a preparation method thereof. The lean duplex stainless steel of the present invention comprises: 0.08 % or less of C; 0.2-3.0 % or less of Si; 2-4 % of Mn; 19-23 % of Cr; 0.3-2.5 % of Ni; 0.2-0.3 % of N; 0.5-2.5 % of Cu; and the balance of Fe and other inevitable impurities by weight. The preparation method of a highly ductile lean duplex stainless steel of the present invention prepares a thin sheet by allowing molten steel to pass through between a pair of casting rolls, wherein nitrogen of an amount over the nitrogen solubility limit in the molten steel is discharged outside through the casting rolls.

Description

technical field [0001] The present invention relates to an economical duplex stainless steel and a preparation method thereof, more particularly, to a high ductility economical duplex stainless steel, wherein in a strip casting process (strip casting process), when the molten steel solidifies, Nitrogen in an amount exceeding the solubility limit of nitrogen is removed, and an annealing heat treatment condition thereof is improved, and a production method thereof is involved. Background technique [0002] In general, austenitic-based stainless steel having excellent workability and corrosion resistance contains iron (Fe) as a base material metal and chromium (Cr) and nickel (Ni) as main raw materials, and the austenite The base stainless steel has been developed into various steels by adding other elements such as molybdenum (Mo), copper (Cu), etc. thereto, thus satisfying various applications. [0003] Since 304-series stainless steel and 316-series stainless steel having c...

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Problems solved by technology

However, 200-series stainless steel and 400-series stainless steel have the disadvantage that their formability and corrosion resistance are not comparable to those of 300-series stainless steel

[0019] However, since the above-mentioned prior art documents still contain a large amount of high-priced Ni, Mo, etc., there is a problem of increased production cost

[0020] In addition, with regard to hot workability, when alloying elements are processed by means of the existing conventional continuous casting method, due to the difference in solid solubility of nitrogen when solidifying from liquid phase to solid phase, the alloying elements in the slab porosity (see figure 1 ), therefore, in subsequent processes such as reheating process and hot rolling process, a large number of defects are generated on the surface of the product, and in order to remove the large number of defects, a separate grinding process must be performed, thus having, for example, no Disadvantages of Necessary Overload

[0021] In addition, if figure 2 As shown, a banded ferrite structure is formed in the transverse direction, thus causing the problem of increased plastic anisotropy, so that the elongation in each rolling direction does not meet the reference value

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