| 摘要 |
PURPOSE:To reduce the brittleness of a nitrided layer and facilitate posttreatment by changing a structure of a compound layer on the external side, which is heat-treated after the nitrided layer is formed by nitriding a metal of iron group. CONSTITUTION:After a nitrided layer composed of the external compound layer and the internal diffusing layer on the nitrided surface of a metal of an iron group, the structure of the compound layer is changed by heat treating. The compound layer becomes structure close to the diffusing layer by the treating, and the hardness is held to reduce the brittleness and to facilitate the posttreatment. Consequently, the surface can be used only by a little grinding after heat treatment, and the surface is porous and can be used for a piston ring and the like of high oil retainment. The heat treating is performed properly at 500-700 deg.C, for 1-5hr in the nitrogen atmosphere, vacuum atmosphere or air atmosphere. |
