DUPLEX STAINLESS STEEL WITH HIGH RESISTANCE TO DISCOLORATION DUE TO CRUDE PHOSPHORIC ACID, AND STRUCTURE FOR CRUDE PHOSPHORIC ACID INCLUDING THE SAME

• Main Authors: NAKATSUJI SATOSHI, MATSUHASHI TORU, TSUGE SHINJI
• Format: Patent
• Language: English; Japanese
• Published: 16.10.2023
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; METALLURGY; TREATMENT OF ALLOYS OR NON-FERROUS METALS

To provide a duplex stainless steel that has economic superiority coupled with a degree of corrosion resistance, exhibiting high resistance to blackening due to crude phosphoric acid.SOLUTION: A duplex stainless steel includes a predetermined component, with the DI value represented by formula 1 being 300 or more, leading to the brightness L* of 65 or more, which can suppress the blackening to a non-discernible level. For example, the duplex stainless steel includes, as the main elements, C: 0.001-0.100%, Si: 0.05-1.50%, Mn: 0.10-2.00%, Cr: 23.0-30.0%, Ni: 4.00-10.00%, Mo: 0.50-3.00%, Cu: 0.01-3.00%, N: 0.10-0.25%, Ca: 0.0010-0.0100%, P: 0-0.050%, and S: 0-0.0040%, with the balance being Fe and inevitable impurities. (Formula 1) DI value=12Cr-Ni+30Mo+2Cu+10N.SELECTED DRAWING: None 【課題】本発明は、経済的に優位であって一定の耐食性を有し、粗製リン酸に対し耐黒変性を有する二相ステンレス鋼を得ることを課題とする。【解決手段】本発明は、所定の成分を有する二相ステンレス鋼であって、式１に示すDＩ値の値が３００以上であることにより、明度Ｌ＊が６５以上となり、黒変を観察できないほど抑制することができる。例えば主要元素としてＣ：０．００１～０．１００％、Ｓｉ：０．０５～１．５０％、Ｍｎ：０．１０～２．００％、Ｃｒ：２３．０～３０．０％、Ｎｉ：４．００～１０．００％、Ｍｏ：０．５０～３．００％、Ｃｕ：０．０１～３．００％、Ｎ：０．１０～０．２５％、Ｃａ：０．００１０～０．０１００％、Ｐ：０～０．０５０％、Ｓ：０～０．００４０％であり残部Ｆｅおよび不可避的不純物の二相ステンレス鋼である。ＤＩ値＝１２Ｃｒ－Ｎｉ＋３０Ｍｏ＋２Ｃｕ＋１０Ｎ ・・・・式１【選択図】なし