STEEL FOR HIGH TOUGHNESS PLASTIC MOLDING MOLD EXCELLENT IN MACHINABILITY AND MIRROR SURFACE PROCESSABILITY

• Main Author: MAEDA MASAHITO
• Format: Patent
• Language: English; Japanese
• Published: 25.05.2017
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; METALLURGY; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PROBLEM TO BE SOLVED: To provide a steel for high toughness plastic molding mold excellent in machinability and also excellent in mirror surface processability.SOLUTION: There is provided a steel for high toughness plastic molding mold excellent in machinability and mirror surface processability, containing, by mass%, C:0.12 to 0.30%, Si:0.26 to 0.37%, Mn:1.10 to 1.80%, S:0.005 to 0.050%, Cr:1.35 to 2.90%, Mo:0.10 to 0.24%, V:0.01 to 0.04%, N:≤0.0180%, Al:≤0.025% and the balance Fe with inevitable impurities and having percentage of Ca and Cr in sulfide contained in the same of Ca:≤5.0%, Cr:≤25.0% and (Ca+Cr):≤28.0%, area ratio of sulfide in the steel of 0.05 to 0.20%, the number of sulfide per 1 mmof ≥9, percentage of the sulfide having area of 50 μmor more in the number of the all sulfide of 2 to 42% and average aspect ratio of the sulfide of ≤9.SELECTED DRAWING: None 【課題】 被削性に優れ、また鏡面加工性にも優れた高靭性プラスチック成形金型用鋼を提供する。【解決手段】 質量％で、Ｃ：０．１２〜０．３０％、Ｓｉ：０．２６〜０．３７％、Ｍｎ：１．１０〜１．８０％、Ｓ：０．００５〜０．０５０％、Ｃｒ：１．３５〜２．９０％、Ｍｏ：０．１０〜０．２４％、Ｖ：０．０１〜０．０４％、Ｎ：≦０．０１８０％、Ａｌ：≦０．０２５％を含有し、残部Ｆｅおよび不可避不純物からなり、これらに含有される硫化物中のＣａ、Ｃｒの割合は、Ｃａ：≦５．０％、Ｃｒ：≦２５．０％、かつ（Ｃａ＋Ｃｒ）：≦２８．０％、これら鋼中の硫化物の面積率：０．０５〜０．２０％、１ｍｍ2当たりの硫化物の個数：≧９個、全硫化物の個数中で５０μｍ2以上の面積を有する硫化物個数の割合：２〜４２％、さらに硫化物の平均アスペクト比：≦９である、被削性および鏡面加工性に優れた高靭性プラスチック成形金型用鋼。【選択図】 なし