Abstract: A raw blank for vacuum carburization is provided. The raw blank for vacuum carburization has a chemical composition containing, by mass, C: 0.13 to 0.28%, Si: 0.01 to 1.20%, Mn: 0.10 to 1.50%, P: 0.030% or less, S: 0.050% or less, Cr: 0.30 to 2.20%, Al: 0.027 to 0.090%, N: 0.0060 to less than 0.0140%, and, as an optional element, Mo: 0.60% or less, the remainder being Fe and unavoidable impurities, and satisfying the following formula (1). AlN precipitates having an equivalent circle diameter of 100 nm or more exist at 1.5 pieces/100 ?m2 or less in a cross section of the raw blank. Al×N?0.00090??(1) It is noted that element symbols in the formula (1) denote a value of content (% by mass) of each element.

Abstract: A chemical composition includes, in mass percent, C: 0.30 to 0.55%, Si: 0.05 to 1.0%, Mn: 0.05 to 0.9%, P: 0.001 to 0.030%, S: 0.005 to 0.12%, Cr: 0.05 to 2.0%, Al: 0.005 to 0.05%, N: 0.0050 to 0.0200%, and the balance being Fe and unavoidable impurities, an amount of N in solid solution being not less than 0.0020%, wherein the contents of Mn and S satisfy relationships expressed by the following expressions: 2.6?Mn/S<15??(1) and Mn+6S<1.2??(2).

Abstract: A chemical composition includes, in mass percent, C: 0.30 to 0.55%, Si: 0.05 to 1.0%, Mn: 0.05 to 0.9%, P: 0.001 to 0.030%, S: 0.005 to 0.12%, Cr: 0.05 to 2.0%, Al: 0.005 to 0.05%, N: 0.0050 to 0.0200%, and the balance being Fe and unavoidable impurities, an amount of N in solid solution being not less than 0.0020%, wherein the contents of Mn and S satisfy relationships expressed by the following expressions: 2.6?Mn/S<15??(1) and Mn+6S<1.2??(2).