Steel wire for mechanical structural parts

Abstract

An object of the present invention is to provide a steel wire for mechanical structural parts that is reduced in deformation resistance and improved in crack resistance during cold working, and thus exhibits excellent cold workability. The steel wire for mechanical structural parts of the present invention is a steel wire containing, in mass %, 0.3 to 0.6% of C, (105 to 0.5% of Si, 0.2 to 1.7% of Mn, more than 0% and 0.03% or less of P, 0.001 to 0.05% of S, 0.005 to 0.1% of Al, and 0 to 0.015% of N, the balance being iron and inevitable impurities, wherein steel of the steel wire has a metal structure formed of ferrite and cementite, and the number proportion of cementite particles present in ferrite grain boundaries is 40% or more based on the total number of cementite particles.

Description

TECHNICAL FIELD[0001]The present invention relates to a steel wire used as a material for mechanical structural parts. More specifically, the present invention relates to a steel wire for mechanical structural parts which, when being produced by spheroidizing annealing and subsequent cold working from a wire rod produced by temper rolling, is low in deformation resistance and good in crack resistance during cold working, and thus exhibits excellent cold workability. The term “wire rod” as used herein refers to a rolled wire rod, which is a wire-like steel material that has been hot-rolled and then cooled to room temperature. The term “steel wire” as used herein refers to a wire-like steel material which is obtained by subjecting a rolled wire rod to tempering treatment such as spheroidizing annealing.BACKGROUND ART[0002]In the production of various mechanical structural parts such as automobile parts and construction machinery parts, a hot-rolled wire rod made of carbon steel, alloy...

AI Technical Summary

Benefits of technology

[0016]The present invention can provide a steel wire for mechanical structural parts that realizes reduction in deformation resistance and improvement in crack resistance since the chemical component composition of the steel is appropriately adjusted, the metal structure of the steel is formed of ferrite and cementite, and the number proportion of cementite particles present in ferrite grain boundaries based on the total number of cementite particles satisfies a prescribed value. The steel wire for mechanical structural parts of the present invention exhibits excellent cold workability since it is reduced in deformation resistance and thus can suppress abrasion and destruction of a plastic working tool such as a die, and since it is also improved in crack resistance and thus can suppress the occurrence of cracks at the time of heading.

Problems solved by technology

In the cold working, lowering the deformation resistance of a steel wire may probably prolong the die life.