| 摘要 |
PURPOSE:To reduce a dimensional change and to improve the durability, especially bending fatigue strength by carrying out heat treatment at a specified low temp. in an atmospheric gas contg. ammonia under partial pressure dropped to a specified range of the partial pressure of gaseous RX by volume. CONSTITUTION:The gas soft-nitriding of a thin maraging steel hoop is carried out at 450-500 deg.C low temp. in an atmospheric gas contg. ammonia under partial pressure dropped to 1/100 1/200 of the partial pressure of gaseous RX by volume. A very thin C and N diffused layer (soft-nitrided layer) can be formed. The soft-nitrided maraging steel hoop has remarkably improved durability, especially bending fatigue strength, and the elongation of the peripheral length of the hoop can be controlled to nearly zero. |
