Nippon Steel Corporation

Shoji Hori

Yutaka Neishi

Naoki Matsui

Keisuke Chiba

Tetsushi Chida

Akihisa Obata

In a rolled steel bar or rolled wire rod for a cold-forged component having a predetermined chemical composition, Y1 represented by Y1=[Mn]&#xd7;[Cr] and Y2 represented by Y2=0.134&#xd7;(D/25.4&#x2212;(0.50&#xd7;&#x221a;[C]))/(0.50&#xd7;&#x221a;[C]) satisfy Y1&#x3e;Y2, the tensile strength is 750 MPa or less, an internal structure is a ferrite-pearlite structure, and the ferrite fraction in the internal structure is 40% or greater. AMOUNT IS 0.30%

Rolled steel bar or rolled wire rod for cold-forged component

In a rolled steel bar or rolled wire rod for a cold-forged component having a predetermined chemical composition, Y1 represented by Y1=[Mn]&#xd7;[Cr] and Y2 represented by Y2=0.134&#xd7;(D/25.4&#x2212;(0.50&#xd7;&#x221a;[C])/(0.50&#xd7;&#x221a;[C]) satisfy Y1&#x3e;Y2, the tensile strength is 750 MPa or less, an internal structure is a ferrite-pearlite structure, and the ferrite fraction in the internal structure is 40% or greater.

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Hokkaido, Japan

Shoji Hori