| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel wire or bar for cold forging hardness of which can be made sufficiently low even when subjected to one time of spheroidization annealing and which is improved in cold forgeability by executing annealing in such a way that the hardness is made uniform, and a method useful for producing such a wire rod and bar for cold forging. SOLUTION: The steel for cold forging has a prescribed chemical composition, in which the average distance between centroids of cementite at an arbitrary section perpendicular to the longitudinal direction of the bar and wire is≥1.5μm; a ferrite particle size is 15 to 60μm; the inclination of the approximate straight line whenβcosθand sinθ(θ:the Bragg angle of the diffraction line) is plotted relating to the half-value widthβof the X-ray diffraction peak at the (110) face, (211) face, and (220) face of the ferrite grains is≤0.00080. COPYRIGHT: (C)2006,JPO&NCIPI
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