PROBLEM TO BE SOLVED: To provide a railroad member capable of improving safety and ride comfort by decreasing a friction coefficient or wear, and saving a maintenance cost; and a surface processing method thereof.
SOLUTION: A wheel W is a railroad wheel wherein a flange surface W2 receiving friction resistance is subjected to surface treatment. The flange surface W2 is a contact surface rotatably contacting with a head side surface of a sharp-curved rail. A nitrided layer 1 is formed by nitriding the flange surface W2, and a hard nitrided layer by nitriding processing for making nitrogen diffuse and permeate on a surface layer of the flange surface W2. A diffused layer 1a is a part formed by diffusing nitrogen on the flange surface W2, and a reaction layer 1b is a part formed by thermal reaction between a wheel W of ferrous metal and nitrogen. A porous layer 1c is a part formed by nitriding the flange surface W2. A large number of minute cavity portions 1e having opening portions 1d on a surface thereof are formed on the porous layer 1c, and lubricant is impregnated in the cavity portions 1e from the opening portions 1d.