UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

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Rule 13d-1(b)

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Rule 13d-1(c)

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Rule 13d-1(d)

CUSIP No.  85811910-0

1.

Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only)
John C. Bates

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4.

Citizenship or Place of Organization
United States

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power
0 shares

6.

Shared Voting Power 
2,395,442 shares

7.

Sole Dispositive Power 
0 shares

8.

Shared Dispositive Power
2,395,442 shares

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
2,395,442 shares

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o
Not applicable.

11.

Percent of Class Represented by Amount in Row (9)
4.9%

12.

Type of Reporting Person (See Instructions)
IN

1.

Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only)
Heidtman Steel Products, Inc.  34-0930923

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4.

Citizenship or Place of Organization
Ohio

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power
0 shares

6.

Shared Voting Power 
2,395,442 shares

7.

Sole Dispositive Power 
0 shares

8.

Shared Dispositive Power
2,395,442 shares

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
2,395,442 shares

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o
Not applicable.

11.

Percent of Class Represented by Amount in Row (9)
4.9%

12.

Type of Reporting Person (See Instructions)
CO

1.

Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only)
Centaur, Inc.  38-2457896

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4.

Citizenship or Place of Organization
Delaware

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power
0 shares

6.

Shared Voting Power 
2,395,442 shares

7.

Sole Dispositive Power 
0 shares

8.

Shared Dispositive Power
2,395,442 shares

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
2,395,442 shares

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o
Not applicable.

11.

Percent of Class Represented by Amount in Row (9)
4.9%

12.

Type of Reporting Person (See Instructions)
CO

Item 1.

(a)

Name of Issuer
This statement relates to the securities of Steel Dynamics, Inc. (the “Company”).

(b)

Address of Issuer’s Principal Executive Offices
The address of the principal executive offices of the Company is:

6714 Pointe Inverness Way
Suite 200
Fort Wayne, IN 46804

Item 2.

(a)

Name of Person Filing (1)
This statement is being filed pursuant to a Joint Filing Agreement, which is attached hereto as Exhibit 1 and incorporated herein by reference, among John C. Bates, Heidtman Steel Products, Inc. (“Heidtman”) and Centaur, Inc.  (“Centaur”).  Mr. Bates is the beneficial owner of a controlling interest in Centaur, which is the sole shareholder of Heidtman.

(b)

Address of Principal Business Office or, if none, Residence

John C. Bates

640 Lavoy Road
Erie, Michigan 48133

Heidtman Steel Products, Inc.

2401 Front St.
Toledo, OH 43560

Centaur, Inc.

640 Lavoy Road
Erie, Michigan 48113

(c)

Citizenship
John C. Bates is a citizen of the United States.  Hiedtman is incorporated under the laws of the State of Ohio. Centaur is incorporated under the laws of the State of Michigan.

(d)

Title of Class of Securities
This statement relates to the Common Stock of the Company, par value $0.01 per share.

(e)

CUSIP Number
85811910-0

Item 3.

If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a)

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Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o).

(b)

o

Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c).

(c)

o

Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c).

(d)

o

Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C 80a-8).

(e)

o

An investment adviser in accordance with §240.13d-1(b)(1)(ii)(E);

(f)

o

An employee benefit plan or endowment fund in accordance with §240.13d-1(b)(1)(ii)(F);

(g)

o

A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);

(h)

o

A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)

o

A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

(j)

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Group, in accordance with §240.13d-1(b)(1)(ii)(J).

Not applicable.

Item 4.

Ownership

Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.

The following information is provided as of December 31, 2004 (2):

Heidtman owns of record 2,395,442 shares of Common Stock.  As Mr. Bates is the controlling shareholder of Centaur, which is the sole shareholder of Heidtman, Mr. Bates shares voting and dispositive power over these shares with Centaur and Heidtman.

(a)

Amount beneficially owned:   

Each of Heidtman, Centaur and Mr. Bates is the beneficial owner of 2,395,442  shares of Common Stock, all of which 2,395,442 shares are owned of record by Heidtman.

(b)

Percent of class:   

The 2,395,442 shares account for 4.9% of 48,485,671 shares of Common Stock, the total number of issued and outstanding shares of the Company as of December 31, 2004.

(c)

Number of shares as to which the person has:

(i)

Sole power to vote or to direct the vote  

Each of Heidtman, Centaur and Mr. Bates has the sole power to vote or to direct the vote of 0 shares of Common Stock.

(ii)

Shared power to vote or to direct the vote    

Each of Heidtman, Centaur and Mr. Bates has the shared power to vote or to direct the vote of 2,395,442 shares of Common Stock.

(iii)

Sole power to dispose or to direct the disposition of   

Each of Heidtman, Centaur and Mr. Bates has the sole power to dispose of or to direct the disposition of 0 shares of Common Stock.

(iv)

Shared power to dispose or to direct the disposition of   

Each of Heidtman, Centaur and Mr. Bates has the shared power to dispose of or to direct the disposition of 2,395,442  shares of Common Stock.

The following information is provided as of December 31, 2003:

Heidtman owns of record 2,795,442 shares of Common Stock.  As Mr. Bates is the controlling shareholder of Centaur, which is the sole shareholder of Heidtman, Mr. Bates shares voting and dispositive power over these shares with Centaur and Heidtman.

(a)

Amount beneficially owned:   

Each of Heidtman, Centaur and Mr. Bates is the beneficial owner of 2,795,442  shares, all of which 2,795,442 shares are owned of record by Heidtman.

(b)

Percent of class:   

The 2,795,442 shares account for 5.7% of 48,645,246 shares of Common Stock, the total number of issued and outstanding shares of the Company as of December 31, 2003, as reported in the Company’s Form 10-K filed March 12,  2004.

(c)

Number of shares as to which the person has:

(i)

Sole power to vote or to direct the vote   

Each of Heidtman, Centaur and Mr. Bates has the sole power to vote or to direct the vote of 0 shares of Common Stock.

(ii)

Shared power to vote or to direct the vote    

Each of Heidtman, Centaur and Mr. Bates has the shared power to vote or to direct the vote of 2,795,442 shares of Common Stock.

(iii)

Sole power to dispose or to direct the disposition of   

Each of Heidtman, Centaur and Mr. Bates has the sole power to dispose of or to direct the disposition of 0 shares of Common Stock.

(iv)

Shared power to dispose or to direct the disposition of   

Each of Heidtman, Centaur and Mr. Bates has the shared power to dispose of or to direct the disposition of 2,795,442  shares of Common Stock.

The following information is provided as of December 31, 2002:

Heidtman owns of record 2,995,442 shares of Common Stock.  As Mr. Bates is the controlling shareholder of Centaur, which is the sole shareholder of Heidtman, Mr. Bates shares voting and dispositive power over these shares with Centaur and Heidtman.

(a)

Amount beneficially owned:   

Each of Heidtman, Centaur and Mr. Bates is the beneficial owner of 2,995,442  shares, all of which 2,995,442 shares are owned of record by Heidtman.

(b)

Percent of class:   

The 2,995,442 shares account for 6.3% of 47,580,676 shares of Common Stock, the total number of issued and outstanding shares of the Company as of December 31, 2002, as reported in the Company’s Form 10-K filed March 28,  2003.

(c)

Number of shares as to which the person has:

(i)

Sole power to vote or to direct the vote   

Each of Heidtman, Centaur and Mr. Bates has the sole power to vote or to direct the vote of 0 shares of Common Stock.

(ii)

Shared power to vote or to direct the vote    

Each of Heidtman, Centaur and Mr. Bates has the shared power to vote or to direct the vote of 2,995,442 shares of Common Stock.

(iii)

Sole power to dispose or to direct the disposition of   

Each of Heidtman, Centaur and Mr. Bates has the sole power to dispose of or to direct the disposition of 0 shares of Common Stock.

(iv)

Shared power to dispose or to direct the disposition of   

Each of Heidtman Centaur and Mr. Bates has the shared power to dispose of or to direct the disposition of 2,995,442  shares of Common Stock.

The following information is provided as of December 31, 2001:

Heidtman owns of record 2,995,442 shares of Common Stock.  As Mr. Bates is the controlling shareholder of Centaur, which is the sole shareholder of Heidtman, Mr. Bates shares voting and dispositive power over these shares with Centaur and Heidtman.

(a)

Amount beneficially owned:   

Each of Heidtman, Centaur and Mr. Bates is the beneficial owner of 2,995,442  shares, all of which 2,995,442 shares are owned of record by Heidtman.

(b)

Percent of class:   

The 2,995,442 shares account for 6.5% of 45,743,473 shares of Common Stock, the total number of issued and outstanding shares of the Company as of December 31, 2001, as reported in the Company’s Form 10-K filed March 28,  2002.

(c)

Number of shares as to which the person has:

(i)

Sole power to vote or to direct the vote   

Each of Heidtman, Centaur and Mr. Bates has the sole power to vote or to direct the vote of 0 shares of Common Stock.

(ii)

Shared power to vote or to direct the vote    

Each of Heidtman, Centaur and Mr. Bates has the shared power to vote or to direct the vote of 2,995,442 shares of Common Stock.

(iii)

Sole power to dispose or to direct the disposition of   

Each of Heidtman, Centaur and Mr. Bates has the sole power to dispose of or to direct the disposition of 0 shares of Common Stock.

(iv)

Shared power to dispose or to direct the disposition of   

Each of Heidtman, Centaur and Mr. Bates has the shared power to dispose of or to direct the disposition of 2,995,442  shares of Common Stock.

The following information is provided as of December 31, 2000:

Heidtman owns of record 3,249,442 shares of Common Stock.  As Mr. Bates is the controlling shareholder of Centaur, which is the sole shareholder of Heidtman, Mr. Bates shares voting and dispositive power over these shares with Heidtman and Centaur.

(a)

Amount beneficially owned:   

Each of Heidtman, Centaur and Mr. Bates is the beneficial owner of 3,249,442  shares, all of which 3,249,442 shares are owned of record by Heidtman.

(b)

Percent of class:   

The 3,249,442 shares account for 7.1% of 45,504,626 shares of Common Stock, the total number of issued and outstanding shares of the Company as of December 31, 2000, as reported in the Company’s Form 10-K filed March 30,  2001.

(c)

Number of shares as to which the person has:

(i)

Sole power to vote or to direct the vote   

Each of Heidtman, Centaur and Mr. Bates has the sole power to vote or to direct the vote of 0 shares of Common Stock.

(ii)

Shared power to vote or to direct the vote    

Each of Heidtman, Centaur and Mr. Bates has the shared power to vote or to direct the vote of 3,249,442 shares of Common Stock.

(iii)

Sole power to dispose or to direct the disposition of   

Each of Heidtman, Centaur and Mr. Bates has the sole power to dispose of or to direct the disposition of 0 shares of Common Stock.

(iv)

Shared power to dispose or to direct the disposition of   

Each of Heidtman, Centaur and Mr. Bates has the shared power to dispose of or to direct the disposition of 3,249,442 shares of Common Stock.

The following information is provided as of December 31, 1998 (3):

Heidtman owns of record 3,030,492 shares of Common Stock.  As Mr. Bates is the controlling shareholder of Centaur, which is the sole shareholder of Heidtman, Mr. Bates shares voting and dispositive power over these shares with Heidtman and Centaur.

(a)

Amount beneficially owned:   

Each of Heidtman, Centaur and Mr. Bates is the beneficial owner of 3,030,492  shares, all of which 3,030,492 shares are owned of record by Heidtman.

(b)

Percent of class:   

The 3,030,492 shares account for 6.3% of 47,864,179 shares of Common Stock, the total number of issued and outstanding shares of the Company as of December 31, 1998, as reported in the Company’s Form 10-K filed March 31,  1999.

(c)

Number of shares as to which the person has:

(i)

Sole power to vote or to direct the vote   

Each of Heidtman, Centaur and Mr. Bates has the sole power to vote or to direct the vote of 0 shares of Common Stock.

(ii)

Shared power to vote or to direct the vote    

Each of Heidtman, Centaur and Mr. Bates has the shared power to vote or to direct the vote of 3,030,492 shares of Common Stock.

(iii)

Sole power to dispose or to direct the disposition of   

Each of Heidtman, Centaur and Mr. Bates has the sole power to dispose of or to direct the disposition of 0 shares of Common Stock.

(iv)

Shared power to dispose or to direct the disposition of   

Each of Heidtman, Centaur and Mr. Bates has the shared power to dispose of or to direct the disposition of 3,030,492 shares of Common Stock.

The following information is provided as of December 31, 1997 (4):

Centaur owns of record 643,426 shares of Common Stock.  Heidtman owns of record 2,237,066 shares of Common Stock.  Keylock owns of record 36,647 shares of Common Stock.  As Mr. Bates is the controlling shareholder of Centaur, which, in turn, is the controlling shareholder of Heidtman, which is the controlling shareholder of Keylock, Mr. Bates, Centaur and Heidtman share voting and dispositive power over the 36,647 shares of Common Stock owned of record by Keylock with Keylock.  Mr. Bates, as controlling shareholder of Centaur, and Centaur, as controlling shareholder of Heidtman, share voting and dispositive power over the 2,237,066 shares of Common Stock owned of record by Heidtman with Heidtman.  As Mr. Bates is the controlling shareholder of Centaur, Mr. Bates shares voting and dispositive power over the 643,426 shares of Common Stock owned of record by Centaur with Centaur. Keylock disclaims beneficial ownership of the Common Stock owned of record by Heidtman and Centaur.  Heidtman disclaims beneficial ownership of the Common Stock owned of record by Centaur.

(a)

Amount beneficially owned:   

Keylock is the beneficial owner of 36,647 shares of Common Stock.  Heidtman is the beneficial owner of 2,273,713 shares of Common Stock, 36,647 of which shares are owned of record by Keylock.  Mr. Bates and Centaur are each the beneficial owners of 2,917,139 shares of Common Stock, 2,237,066 of which shares are owned of record by Heidtman, 643,426 of which shares are owned of record by Centaur and 36,647 of which shares are owned of record by Keylock.

(b)

Percent of class:   

The 36,647 shares of Common Stock held of record by Keylock account for 0.1% of 49,056,273 shares of Common Stock, the total number of issued and outstanding shares of the Company as of December 31, 1997, as reported in the Company’s Form 10-K filed March 27, 1998.  The aggregate 2,273,713  shares of Common Stock held of record by Heidtman and Keylock account for 4.6% of the 49,056,273 shares outstanding as of December 31, 1987.  The aggregate 2,917,139 shares of Common Stock held of record by Keylock, Centaur and Heidtman account for 5.9% of the 49,056,273 shares of Common Stock outstanding as of December 31, 1997.

(c)

Number of shares as to which the person has:

(i)

Sole power to vote or to direct the vote   

Each of Heidtman, Centaur and Mr. Bates has the sole power to vote or to direct the vote of 0 shares of Common Stock.

(ii)

Shared power to vote or to direct the vote    

Each of Centaur and Mr. Bates has the shared power to vote or to direct the vote of 2,917,139 shares of Common Stock.  Heidtman has the shared power to vote or to direct the vote of 2,273,713 shares of Common Stock.  Keylock has the shared power to direct the vote of 36,647 shares of Common Stock.

(iii)

Sole power to dispose or to direct the disposition of   

Each of Heidtman, Centaur and Mr. Bates has the sole power to dispose of or to direct the disposition of 0 shares of Common Stock.

(iv)

Shared power to dispose or to direct the disposition of   

Each of Centaur and Mr. Bates has the shared power to dispose of or to direct the disposition of 2,917,139 shares of Common Stock.  Heidtman has the shared power to dispose of or to direct the disposition of 2,273,713 shares of Common Stock.  Keylock has the shared power to dispose of or direct the disposition of 36,647 shares of Common Stock.

Item 5.

Ownership of Five Percent or Less of a Class

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following   ý.

Each of Centaur, Mr. Bates and Heidtman is no longer the beneficial owner of more than 5% of the Common Stock of the Company.  Mr. Bates, however, remains a director of the Company.

Item 6.

Ownership of More than Five Percent on Behalf of Another Person

Not applicable.

Item 7.

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person

Not applicable.

Item 8.

Identification and Classification of Members of the Group

Not applicable.

Item 9.

Notice of Dissolution of Group

Not applicable.

Item 10.

Certification

The following certification shall be included if the statement is filed pursuant to Rule 13d-1(c):

Date:   March 16, 2005

 /s/ John C. Bates

John C. Bates

Heidtman Steel Products, Inc.

By:

 /s/ John C. Bates

Name: John C. Bates

Title:   Chief Executive Officer

Centaur, Inc.

By:

 /s/ John C. Bates

Name: John C. Bates

Title:   Chief Executive Officer

Exhibit 1

Joint Filing Agreement, dated as of March 16, 2005, between John C. Bates, Heidtman Steel Products, Inc. and Centaur, Inc.