Abstract:
PROBLEM TO BE SOLVED: To provide a crankshaft having sufficiently high strength, and small in deformation caused by quenching; and to provide its manufacturing method. SOLUTION: This crankshaft is provided with a crankpin 1, a crank journal 2, and a crank arm 3 for linking the crankpin 1 and the crank journal 2, and includes a pin fillet portion 4P located between the crankpin 1 and the crank arm 3, and a journal fillet portion 4J located between the crank journal 2 and the crank arm 3. The crankpin 1 and/or the crank journal 2 have/has a diameter of 20-40 mm. At least one of the pin fillet portion 4P and the journal fillet portion 4J contains a quench-hardened layer 5 having a thickness of 1-2 mm in the vicinity of a surface thereof. Each of the crankpin 1 and the crank journal 2 does not substantially contain any quench-hardened layer having a thickness exceeding 2 mm in the vicinity of a surface thereof. COPYRIGHT: (C)2009,JPO&INPIT