| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing high strength shaft parts excellent in cold workability and induction hardenability even without executing spheroidizing and refining treatment, and in which the hardness of the shaft part is 95 or more by Rockwell B hardness. SOLUTION: A slab having a chemical composition containing 0.40 to 0.60% C, 0.10 to 0.60% Mn, 0.005 to 0.05% Nb, 0.015 to 0.10% Al, 0.0005 to 0.005% B, 0 to 0.40% Si, 0 to 0.05% Ti, and the balance Fe with impurities, and in which, in the impurities, the content of P is controlled to <=0.015%, S to <=0.015%, Cu to <=0.10%, Ni to <=0.10%, Cr to <=0.15%, Mo to <=0.10%, N to <=0.0050% and O to <=0.005%, is heated at 1000 to 1250 deg.C, is hot-rolled so as to control the rolling finishing temperature to 1000 to 800 deg.C, is cooled at a cooling rate of 0.5 to 5 deg.C/sec at least to 500 deg.C after the completion of the hot rolling, is next subjected to wire drawing in such a manner that the total reduction of area is controlled to 25 to 50%, is moreover subjected to cold working to form into a prescribed shape and is subsequently subjected to induction hardening.
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