Gas soft nitriding method and gas soft nitriding apparatus

摘要

PROBLEM TO BE SOLVED: To provide a gas soft-nitriding method and a gas soft-nitriding device that can efficiently carry out gas soft-nitriding.SOLUTION: A gas soft-nitriding method is designed to heat a work of carbon steel or low alloy steel stored in a heat processing furnace and to supply a base gas including ammonia and an additional gas including chain unsaturated hydrocarbon into the heat processing furnace. There are set a first period tin which the base gas and additional gas are supplied into the heat processing furnace while the inside of the heat processing furnace in which the work is stored is held at a predetermined soft-nitriding temperature T and a second period tin which only the base gas is supplied into the heat processing furnace while the inside of the heat processing furnace is held at the soft-nitriding temperature T after the first period t1. The length of the first period tis set to be equal to or longer than the length of the second period t.SELECTED DRAWING: Figure 2