Method for manufacturing fuel injection component

A method for manufacturing a fuel injection component by processing a workpiece into a predetermined shape, wherein the workpiece is made of a steel having compositions, by mass %, of

• C:
• 0.08 to 0.16%,
• Si:
• 0.10 to 0.30%,
• Mn:
• 1.00 to 2.00%,
• S:
• 0.005 to 0.030%,
• Cu:
• 0.01 to 0.30%,
• Ni:
• 0.40 to 1.50%,
• Cr:
• 0.50 to 1.50%,
• Mo:
• 0.30 to 0.70%,
• V:
• 0.10 to 0.40%,
• s-Al:
• 0.001 to 0.100%, and
• Fe and unavoidable impurities as remaining components,
• the method comprising:
• subjecting the workpiece to hot forging after heating the workpiece to a temperature of 950° C. or more and 1350° C. or less;
• first cooling the workpiece, after the hot forging, at an average cooling rate of 0.1° C./sec. or more in a temperature range from 800° C. to 500° C.;
• and
• second cooling the workpiece, after the first cooling, at an average cooling rate of 0.02° C./sec. or more and 10° C./sec. or less in a subsequent temperature range from 500° C. to 300° C. to set an area ratio of a bainite structure after hot forging to 85% or more.