| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing an endless metallic belt capable of easily selecting rings with a circumferential length fittable to rings after aging treatment and nitriding treatment. SOLUTION: Rings 4 formed by subjecting a drum 2 formed by welding the end parts of a thin sheet 1 of maraging steel to cut to prescribed widths are rolled and are thereafter subjected to circumferential length correction, and the rings 4 subjected to the circumferential length correction are subjected to aging treatment and nitriding treatment. The aging treatment is executed in such a manner that the rings 4 subjected to the circumferential length correction are held at 450 to 500 deg.C for 2 to 3 hr, and the circumferential length of the ring 4 after the nitriding treatment lies in a prescribed error range to the circumferential length of the rings 4 after the circumferential length correction. The nitriding treatment is executed in such a manner that, directly after the aging treatment, the rings 4 are held in an atmosphere of gaseous ammonia previously heated to a nitriding temperature or in a mixed atmosphere of gaseous ammonia and gaseous RX under holding to the nitriding temperature for a prescribed time. The nitriding treatment is executed so that the thickness of a nitrided layer 14 is controlled to 20 to 40% of the thickness of the whole of the rings 4.
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