Exhibit 5.1

[Letterhead of Barrett & McNagny LLP]


_________________, 2002


Steel Dynamics, Inc.
6714 Pointe Inverness Way, Suite 200
Fort Wayne, Indiana  46804

Re: Steel Dynamics, Inc.
    Registration Statement on Form S-3

Gentlemen:

In connection with the registration on Form S-3 under the Securities Act of
1933, as amended (the "Act") by Steel Dynamics, Inc. (the "Company") of
approximately $_________________ of its Common Stock, in a proposed public
offering, we have examined such corporate records, certificates, agreements, and
other documents, and have reviewed such questions of law as we have considered
necessary or appropriate for purposes of this opinion.

This opinion is being furnished in accordance with the requirement of Item
601(b)(5) of Regulation S-K promulgated under the Act.

On the basis of such examination and review, we advise you that, in our opinion,
when the Registration Statement on Form S-3, filed by the Company herewith with
respect to such offering of its Common Stock shall have become effective under
the Act, when the shares shall have been sold in accordance with the terms set
forth in the applicable Underwriting Agreement between the Company and Morgan
Stanley & Co. Incorporated and JP Morgan Securities Inc., as the representative
of the underwriters identified therein, and when the certificates evidencing the
shares of Common Stock purchased in connection herewith shall have either been
physically issued, executed, authenticated and delivered by the Company and by
EquiServe Trust Company, N.A. as transfer agent and/or when the shares shall
have otherwise been duly issued and transferred in electronic form, the shares
of Common Stock will be validly and legally issued and outstanding, will be
fully paid and non-assessable, and will be entitled to the benefits described
for the Common Stock in the Company's Amended and Restated Articles of
Incorporation.

Our opinion is limited to the general corporation laws of the State of Indiana
and the federal laws of the United States of America. We express no opinions as
to any other laws, statutes, rules or regulations.