The steel for machine structural use is a free-cutting steel excellent in the friability of chips.

The sulfur-containing free-cutting steel, which does not need a heavy metal affecting adversely the environment, exhibits good machinability comparable to a free-cutting steel containing a heavy metal.

When cut with a high-speed steel tool, the steel material has the same chip disposability as conventional Pb-free free-cutting steel materials and has better finished-surface properties than those.

Free-cutting steel with an average carbon content; the addition of tellurium allows an even better machinability.

Free-cutting steel with sulfur only, with a high carbon content to obtain optimal hardness after tempering.

The structural steel contains no Pb and has properties which are same as or superior to those of a conventional free cutting steel containing Pb.

In addition, the method according to the present invention is also applicable to making all the High Sulphur Cast Steel including antifriction and wear-resistance steel and free cutting steel that contain some sulphur.

Provided is a lead-containing free-machining steel having excellent machinability.

Provided is a free machining steel with lead having excellent machinability.

The housing or a part of the housing is produced from machining steel by machining.

This lead-containing free-machining steel contains, in terms of mass%, 0.005-0.2% C, 0.3-2.0% Mn, 0.005-0.2% P, 0.01-0.7% S, 0.03-0.5% Pb, 0.004-0.02% N, and 0.003-0.03% O, with the remainder comprising Fe and impurities.