Nitriding steel excellent in nitriding properties

摘要

PROBLEM TO BE SOLVED: To provide a steel for nitriding which allows a layer hardened by nitriding to be formed on a steel component for mechanical structure such as a gear by nitriding the steel component.SOLUTION: In one embodiment, there is provided a steel for nitriding excellent in nitriding property having a martensite structure obtained by hardening and tempering a steel containing, by mass%, C:0.10 to 0.40%, Si:0.10 to 0.50%, Mn:0.50 to 1.50%, P:0.030% or less, S:0.030% or less, Cr:0.50 to 1.50%, Mo:0.05 to 0.30%, Al:0.15 to 0.80%, N:0.005 to 0.030% or further containing one or more kind of V:0.05 to 0.35%, Ti:0.05 to 0.30%, Nb:0.03 to 0.30% and the balance Fe with inevitable impurities. In another embodiment, when the component composed of the above steel is nitride, the above steel has a ratio between the number of deposits of Al nitride and carbonitride in the nitride and carbonitride of the component and the number of deposits of Cr nitride and carbonitride of 0.2 or more.