Low-carbon resulfurized free-cutting steel material

Abstract

A low-carbon resulfurized free-cutting steel material which contains less than 0.05% C, less than 0.05% Si, 0.7-2.2% Mn, 0.03-0.20% P, 0.40-0.70%, excluding 0.40% and 0.70%, S, less than 0.005% Al, 0.0050-0.0380% O, and 0.0020-0.0250% N, with the remainder being iron and impurities, wherein Ca, Mg, Ti, Zr, and REM among the impurities satisfy the following relationships: Ca<0.001%, Mg<0.001%, Ti<0.002%, Zr<0.002%, and REM<0.001%, provided that 0.010<O / S<0.080 and 2.5<Mn / (S+O)<4.0. When cut with a high-speed steel tool, the steel material has the same chip disposability as conventional Pb-freefree-cutting steel materials and has better finished-surface properties than those. It is excellent also in continuous castability and hence suitable for mass production. This material may contain atleast one of Te=0.05%, Bi=0.15%, and Se<0.30%.

Description

Low carbon sulfur free cutting steel technical field The present invention relates to a low-carbon sulfur free-cutting steel, and more specifically, to a lead free-cutting steel (hereinafter referred to as "Pb free-cutting steel") and a composite free-cutting steel added with S and Pb, namely "sulfur composite free-cutting steel". Low-carbon sulfur free-cutting steel that has better machinability than existing free-cutting steel without adding Pb, which is used as an alternative material to "Steel" (hereinafter referred to as "S composite free-cutting steel"). More specifically, it relates to a low-carbon sulfur free-cutting steel without adding Pb, which uses a high-speed steel tool (hereinafter referred to as "HSS" tool.) in a relatively low speed range of 100 m / min or less, And when cutting under wet conditions with the supply of cutting oil, it has the property that the chips can be divided into finer pieces (hereinafter referred to as "chip disposability"), and has the p...

AI Technical Summary

Problems solved by technology

As mentioned above, the free-machining steel without adding Pb that has been proposed so far has machinability necessary as a raw material for soft small parts such as brake parts for automobiles, personal computer peripheral parts, and electrical equipment parts. , in the relatively low speed area below 100m / min, the final machined surface properties after cutting a long distance with HSS tools, that is, the final machined surface roughness, cannot be said to be able to meet the requirements of the industry.

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