| 摘要 |
PROBLEM TO BE SOLVED: To provide a rotor for a disc brake decreased in cost and having high friction resistance. SOLUTION: After gas soft nitrating treatment is applied on a material formed of JIS FC250 formed through sand mold casting finished in a rotor shape, the material is heated and held at temperature higher than an A1 transformation point and lower than an eutectic temperature and by causing isothermal transformation of a nitrogen diffusion layer formed through nitriding and a matrix through holding of it in a heat bath at a given temperature, a rigid nitrogen compound layer is formed on the surface of the rotor. Further, since the nitrogen diffusion layer at the lower layer of the nitrogen compound layer and the matrix are brought into a bainitic texture high in hardness, wear resistance of a rotor is improved.
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