| 摘要 |
<p>PURPOSE: To provide a method for performing nitriding at high nitriding efficiency so that a high N material is manufactured, wherein the nitriding is advantageous in terms of productivity in separately manufacturing steel materials and in manufacturing high functional steel. CONSTITUTION: The method comprises a process of nitriding a metallic material having temperature that is 20 deg.C or more than that of the nitriding atmosphere as maintaining 600 deg.C or more of temperature at a nitriding atmosphere comprising gases in which one of the constituting elements of a gas molecule is N (except N2 gas) and having a temperature range from a room temperature to 800 deg.C or less, wherein the gases in which one of the constituting elements of a gas molecule is N are 0.5 to 100 % (volume ratio) of the nitriding atmosphere, wherein at least one gas out of the gases in which one of the constituting elements of a gas molecule is N is ammonia gas, wherein the nitriding atmosphere contains 1.0 vol.% or more of hydrogen gas, wherein the nitriding atmosphere is a mixed gas comprising ammonia gas and nitrogen gas, the nitrogen gas is 10 vol.% or more of the nitriding atmosphere, and amount of nitrogen gas/(amount of nitrogen gas+amount of hydrogen gas) is 0.60 or more, and the atmospheric gas has a dew point of -10 deg.C or more.</p> |
