non-heat treated mechanical parts for wire, non-heat treated mechanical parts for steel wire, and, and the non-heat treated mechanical parts methods for their preparation

摘要

The tensile strength is used in the manufacture of non-heat treated mechanical parts 900~1300MPa A wire, by mass% C: 0.20~0.50%, Si: 0.05~2.0%, Mn: it contains 0.20~1.0%, P: 0.030% Hereinafter, S: 0.030% or less, N: is limited to 0.005% or less, an F1 is less than 0.60 to be defined by the following equation (1), the balance being Fe and unavoidable impurities, metal structure , wherein the volume ratio at 64 (C%) + 52% or more pearlite structure, and the balance of one or two kinds of pro-eutectoid ferrite structure and bainite structure, when the diameter of the wire is set to D, 0 from the surface layer. the average block particle size of the pearlite structure of the region up to 1D is 15 m or less, and, (average particle size block of pearlite structure of the region from the surface up to 0.1D) / (pearlite structure in the range of from 0.25D to center The average particle size of the block) is less than 1.0. F1 = C (%) + Si (%) / 24 + Mn (%) / 6 (1)