A carbonitrided part, where a base steel contains, in
mass percent, C: 0.10 to 0.35%, Si: 0.15 to 1.0%, Mn: 0.30 to 1.0%, Cr: 0.40 to 2.0%, S≦0.05%, and according to need further Mo≦0.50%, with the balance being Fe and impurities, and in the region to a position of effective hardening depth from the surface of a hardened layer of the carbonitrided part,
iron nitride particles of ε-Fe3N and / or ζ-Fe2N are dispersed, and retained
austenite is decomposed into bainitic ferrite, Fe3C, and α″-Fe16N2 has excellent abrasion strength and high pitting strength, although the base steel is a low-cost one with less content of Mo of an expensive
alloy element or without addition of Mo. This carbonitrided part can be produced, for example, by subjecting the base steel part to
carburizing in which the base steel part is held in a
carburizing atmosphere at 900 to 950° C. and successively to
carbonitriding in which the base steel part is held in a
carbonitriding atmosphere with a
nitrogen potential of 0.2 to 0.6% at 800 to 900° C., subsequently
quenching the base steel part, and thereafter
tempering the base steel part by heating to a temperature in the range of more than 250° C. to not more than 350° C.