CASE HARDENED STEEL FOR WARM FORGING AND FORGED BLANK MANUFACTURED USING THE SAME

• Main Authors: TAKAO RYOTA, YUTANI TOMOAKI, YOKOI SHUHEI, SUGIURA TAKAYOSHI, SHIMADA TAKEYUKI
• Format: Patent
• Language: English; Japanese
• Published: 04.07.2022
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; FORGE FURNACES; FORGING; HAMMERING; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; METALLURGY; PERFORMING OPERATIONS; PRESSING METAL; PUNCHING METAL; RIVETING; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS

To provide a case hardened steel having excellent machinability after warm forging, and a forged blank that has undergone warm forging by using the same and has excellent machinability.SOLUTION: This case hardened steel is for warm forging at a forging temperature of 850-1100°C. The case hardened steel contains 0.15-0.23% of C, 0.60-0.95% of Si, 0.60-1.20% of Mn, 0.035% or less of P, 0.035% or less of S, 1.50% or less (but excluding 0%) of Cr, 0.050% or less of Al, 0.01-0.05% of Ti, 0.0005-0.0050% of B, 0.0020-0.0200% of N, 0.20% or less of Mo as an optional element, 0.01-0.05% of Nb as an optional element, the balance being Fe and unavoidable impurities, and satisfies formula 1 and formula 2. Formula 1: 90≥-120*C+20.1*Si-5.3*Mn-8.5*Mo+96≥80 and Formula 2: 160≥40*Si+39*Mn+10*Cr+30*Mo+84≥145.SELECTED DRAWING: None 【課題】温間鍛造後の切削性に優れた肌焼鋼及びこれを用いて温間鍛造を施した切削性に優れた鍛造粗形材を提供すること。【解決手段】鍛造温度８５０℃～１１００℃の温間鍛造用の肌焼鋼である。Ｃ：０．１５～０．２３％、Ｓｉ：０．６０～０．９５％、Ｍｎ：０．６０～１．２０％、Ｐ：０．０３５％以下、Ｓ：０．０３５％以下、Ｃｒ：１．５０％以下（０％は除く）、Ａｌ：０．０５０％以下、Ｔｉ：０．０１～０．０５％、Ｂ：０．０００５～０．００５０％、Ｎ：０．００２０～０．０２００％を含み、任意元素としてＭｏ：０．２０％以下、任意元素としてＮｂ：０．０１～０．０５％を含み、残部がＦｅ及び不可避的不純物からなり、式１及び式２を満たす。式１：９０≧－１２０＊Ｃ＋２０．１＊Ｓｉ－５．３＊Ｍｎ－８．５＊Ｍｏ＋９６≧８０、式２：１６０≧４０＊Ｓｉ＋３９＊Ｍｎ＋１０＊Ｃｒ＋３０＊Ｍｏ＋８４≧１４５【選択図】なし