| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel wire rod for spring, minimal in central segregation and excellent in cold workability such as cold coiling property. SOLUTION: The total area index (SE) of central segregation grains which exist within an arbitrary 1-mm<2> observational field plane including the central point of the cross section of a rolled steel wire rod and in which C, Mn, and P exist independently or coexist, determined by equation SE=-(1/√C)×log(S/ D<2> ), is regulated to >=5. In the equation, C, D, and S represent the carbon content in the rolled steel wire rod (mass %), the diameter of the rolled steel wire rod (mm), and the total area of the segregation grains (mm<2> ), respectively.
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