CASE HARDENED STEEL FOR GAS CARBURIZATION, AND GAS CARBURIZATION

To provide a case hardened steel for gas carburization capable of enhancing fatigue strength of a carburization component by reducing imperfection hardening layer depth generated during gas carburization hardening while suppressing increase of manufacturing cost.SOLUTION: A case hardened steel for gas carburization contains, by mass%, C:0.10 to 0.30%, Si:0.01 to 1.50% or less, Mn:0.30 to 2.00%, P:0.03% or less, S:0.05% or less, Cu:0.01 to 1.00%, Ni:0.01 to 3.00%, Cr:0.01 to 3.00%, Mo:0.01 to 2.00%, Al:0.10 to 2.00%, N:0.050% or less, O:0.0015% or less, and the balance Fe with inevitable impurities, and satisfies the following formula (1). F1≥0.1 Formula (1) F1=[Al]-1.9[N]-1.1[O], wherein [] in F1 represents content mass% of an element in [].SELECTED DRAWING: None 【課題】製造コストの上昇を抑えつつ、ガス浸炭焼入れ時に生成される不完全焼入層深さを低減して浸炭部品の疲労強度を高めることが可能なガス浸炭用肌焼鋼を提供する。【解決手段】ガス浸炭用肌焼鋼は、質量％で、Ｃ：０．１０〜０．３０％，Ｓｉ：０．０１〜１．５０％以下，Ｍｎ：０．３０〜２．００％，Ｐ：０．０３％以下，Ｓ：０．０５％以下，Ｃｕ：０．０１〜１．００％，Ｎｉ：０．０１〜３．００％，Ｃｒ：０．０１〜３．００％，Ｍｏ：０．０１〜２．００％，Ａｌ：０．１０〜２．００％，Ｎ：０．０５０％以下，Ｏ：０．００１５％以下，残部がＦｅ及び不可避的不純物であり、且つ下記式（１）を満たすことを特徴とする。Ｆ１≧０．１・・式(１) 但しＦ１＝[Al]-1.9[Ｎ]-1.1[Ｏ]（Ｆ１の式中[ ]は、[ ]内元素の含有質量％を表す）【選択図】 なし