NITRIDING QUENCHING METHOD AND NITRIDED QUENCHED PART

PROBLEM TO BE SOLVED: To provide a nitriding quenching method which can obtain a desired nitrogen penetration depth in a short time instead of the conventional nitriding quenching treatment where, since treatment has been performed at ≥600°C over the whole process of the treatment, nitrogen penetration velocity to the surface of a workpiece is slow, and a long time has been required for obtaining a desired nitrogen penetration depth, and to provide a nitrided quenched part. SOLUTION: Disclosed is a nitriding quenching method where nitrogen is penetratively diffused into a workpiece composed of iron or an iron alloy, and further, quenching is performed. A workpiece is installed in a heat treatment furnace to be fed with an ammonia gas, the temperature in the heat treatment furnace is increased to a temperature Ta in a ferrite region of the workpiece, so as to be held for a prescribed time t1, thereafter, the temperature in the heat treatment furnace is increased to a temperature Tb in an austenite region of the workpiece, so as to be held for a prescribed time t2, and subsequently, the workpiece is rapidly cooled and is quenched. COPYRIGHT: (C)2010,JPO&INPIT