| 摘要 |
The invention is to provide a method of manufacturing a mechanical structural shaft component improved in the fatigue strength and maintained in the manufacturability, and a mechanical structural shaft component manufactured by the method. The shaft component is manufactured by blending and melting a raw material so as to achieve a steel material composition of, in % by mass, Fe: 96% or more, C: 0.45% or more and 0.55% or less, Si: 0.02% or more and 0.15% or less, Mn: more than 0.50% and 1.20% or less, P: 0.005% or more and 0.020% or less, S: 0.005% or more and 0.030% or less, Cr: 0.10% or more and 0.30% or less, Al: 0.002% or more and 0.050% or less, Ti: 0.020% or more and 0.050% or less, B: 0.0005% or more and 0.0030% or less and Nb: 0.020% or more and 0.100% or less; by allowing the raw material to solidify, while keeping cooling rate of the center portion of a bloom at 2° C./min or above; and by subjecting the resultant steel material to product rolling or forging at a heating temperature of 950° C. to 1,050° C., and at a working temperature of 800° C. to 1,050° C., to thereby make the steel material having a geometry of shaft component, and further to induction hardening and tempering.
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