STEEL FOR HIGH FREQUENCY HARDENING AND MANUFACTURING METHOD THEREFOR

PROBLEM TO BE SOLVED: To provide a steel for high frequency hardening capable of achieving excellent rolling fatigue life.SOLUTION: There is provided a steel for high frequency hardening containing C:0.4 to 0.6%, Si:0.03 to 1.0%, Mn:0.20 to 2.0%, P:0.05% or less, S:0.0005 to 0.01%, Cr:0.05 to 0.50%, Al:0.01 to 0.10%, Ca:0.0003 to 0.0030%, Mg:0.0001 to 0.003%, O:0.0030% or less, N:0.003 to 0.030%, Cu:0 to 1.0%, Ni:0 to 3.0%, Mo:0 to 0.15%, V:0 to 0.30%, Nb:0 to 0.10%, B:0 to 0.0030% and Ti:0 to 0.10% and (A) having maximum inclusion diameter √areaof 50 μm or less, (B) of which 50% or more contains both of oxide and sulfide of 5 mass% or more and having (C) the content when making three dimension oxide of CaO-AlO-Mg and (D) CaS and MnS contents in specific ranges.SELECTED DRAWING: None 【課題】優れた転動疲労寿命を確保できる高周波焼入れ用鋼の提供。【解決手段】Ｃ：０．４〜０．６％、Ｓｉ：０．０３〜１．０％、Ｍｎ：０．２０〜２．０％、Ｐ：０．０５％以下、Ｓ：０．０００５〜０．０１％、Ｃｒ：０．０５〜０．５０％、Ａｌ：０．０１〜０．１０％、Ｃａ：０．０００３〜０．００３０％、Ｍｇ：０．０００１〜０．００３％、Ｏ：０．００３０％以下、Ｎ：０．００３〜０．０３０％、Ｃｕ：０〜１．０％、Ｎｉ：０〜３．０％、Ｍｏ：０〜０．１５％、Ｖ：０〜０．３０％、Ｎｂ：０〜０．１０％、Ｂ：０〜０．００３０％およびＴｉ：０〜０．１０％を含有し、（Ａ）最大介在物径√ａｒｅａｍａｘが５０μｍ以下（Ｂ）５０％以上が、酸化物と硫化物をともに質量％で５％以上含む（Ｃ）ＣａＯ−Ａｌ2Ｏ3−ＭｇＯの３元系酸化物としたときの含有量と、（Ｄ）ＣａＳ、ＭｎＳの含有量と、が特定範囲にあることを満足する高周波焼入れ用鋼。【選択図】なし