| 摘要 |
According to one embodiment of the present invention, the chemical composition of a steel material for induction hardening includes a prescribed amount of alloying elements, the remainder comprises Fe and impurities, Al×N is 0.000330-0.000825, and Mn/S is 4.6-14.0. The machinability index (M) is 15.5-25.65. At a 1/4 diameter location, the area ratio of AlN for an equivalent circle diameter exceeding 200 nm is 20% or less of the area ratio of all AlN for an equivalent circle diameter of 40 nm or more. At the 1/4 diameter location, the number density of Mn sulphide inclusions of a maximum diameter of 0.3-10 µm inclusive is 100-2500 per mm |
