Austenitic stainless steel having improved strength

Abstract

An austenitic stainless steel with improved strength is disclosed. The austenitic stainless steel includes, in percent (%) by weight of the entire composition, C: 0.02 to 0.14%, Si: 0.2 to 0.6%, S: less than 0.01%, Mn: 2.0 to 4.5%, Ni: 2.5 to 5.0%, Cr: 19.0 to 22.0%, Cu: 1.0 to 3.0%, Mo: less than 1.0%, N: 0.25 to 0.40%, the remainder of iron (Fe) and other inevitable impurities, and the Solubility of Nitrogen in Liquid (SNL) value represented by the following equation (1) is equal to or greater than the content of N. Equation (1): SNL=−0.188−0.0423×C−0.0517×Si+0.012×Mn+0.0048×Ni+0.0252×Cr−0.00906×Cu+0.00021×Mo. Here, C, Si, Mn, Ni, Cr, Cu, and Mo mean the content (% by weight) of each element.

Description

TECHNICAL FIELD[0001]The present disclosure relates to austenitic stainless steel, in particular, to austenitic stainless steel with improved strength while securing elongation and corrosion resistance.BACKGROUND ART[0002]Stainless steel refers to steel that has strong corrosion resistance by suppressing corrosion, a weak point of carbon steel. In general, stainless steel is classified according to its chemical composition or metal structure. According to the metal structure, stainless steel can be classified into austenite, ferrite, martensite and dual phase.[0003]Among them, austenitic stainless steel is a steel containing a large amount of chromium (Cr) and nickel (Ni), and is most commonly used. For example, 316L stainless steel has a component based on 16-18% Cr, 10-14% Ni, and 2-3% molybdenum (Mo), is applied in various industrial fields by securing corrosion resistance and molding properties.[0004]However, in the case of Ni and Mo, there is a problem in terms of price competi...

AI Technical Summary

Benefits of technology

The patent text describes a way to make a type of stainless steel that is stronger, while also maintaining its flexibility and resistance to corrosion. This can be done by using a specific process with existing materials.

Problems solved by technology

However, in the case of Ni and Mo, there is a problem in terms of price competitiveness due to high material prices, and raw material supply and demand are unstable due to extreme fluctuations in material prices, and it is difficult to secure supply price stability.

By this component-based design, 216 stainless steel can secure a level of corrosion resistance similar to that of 316L stainless steel, but due to the generation of a large amount of Mn fume during the steel making process due to the addition of a large amount of Mn, not only environmental improvement is required, but also the production of steel making inclusions (MnS) results in a decrease in productivity in the manufacturing process and a decrease in the surface quality of the final material.

However, in the case of lean duplex stainless steel, there is a problem in that the formability and elongation are inferior due to the formation of an phase interface between austenite and ferrite.

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