Steel wire for non-thermal-refined machine component, and non-thermal-refined machine component

Abstract

A steel wire for a non-thermal-refined machine component, the steel wire including, in terms of mass%, 0.20-0.40% C, 0.05-0.50% Si, 0.50-2.00% Mn, and 0.005-0.050% Al, the remainder including Fe and impurities, the metallographic structure including (35 x [C%] + 50)% or more of bainite, and AR being 1.4 or greater, (AR) / (average aspect ratio of bainite particles at a position a depth of 0.25 D inthe L cross-section) being 1.1 or greater, GD being (15 / AR) [mu]m or less, and (GD) / (average particle diameter of bainite particles at a position a depth of 0.25 D in the C cross-section) being less than 1.0, where D is the diameter of the steel wire, AR is the average aspect ratio of bainite particles at a position a depth of 50 [mu]m in the L cross-section, and GD is the average particle diameter of bainite particles at a position a depth of 50 [mu]m in the C cross-section.

Description

technical field [0001] The application relates to a steel wire for a non-quenched and tempered mechanical part and a non-quenched and tempered mechanical part. Background technique [0002] In recent years, in the fields of various machines such as automobiles and construction, there has been an increasing demand for high-strength machine parts from the viewpoint of weight reduction and space saving. [0003] However, as the strength of the high-strength mechanical parts increases, especially when the tensile strength of the high-strength mechanical parts is 1100 MPa or more, fractures caused by hydrogen embrittlement (that is, the hydrogen embrittlement resistance characteristics become more likely to occur) fall easily). [0004] As a method of improving the hydrogen embrittlement resistance of high-strength mechanical parts, a method of making the structure into a pearlite structure and strengthening the structure by wire drawing is known, and a large number of methods h...

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Problems solved by technology

[0003] However, as the strength of the high-strength mechanical parts increases, especially when the tensile strength of the high-strength mechanical parts is 1100 MPa or more, fractures caused by hydrogen embrittlement (that is, the hydrogen embrittlement resistance characteristics become more likely to occur) fall easily)

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