<PAGE>   1


    As filed with the Securities and Exchange Commission on March 7, 1997
                                                     Registration No. 333-______


                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                                        
                        --------------------------------

                                    FORM S-8

            REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

                       -------------------------------

                               QUANEX CORPORATION
             (Exact name of registrant as specified in its charter)

      DELAWARE                                        38-1872178
(State or other jurisdiction of                      (I.R.S Employer
incorporation or organization)                       Identification No.)

1900 WEST LOOP SOUTH, SUITE 1500
     HOUSTON, TEXAS                                       77027
(Address of Principal Executive Offices)                (Zip Code)
                      


                           PIPER IMPACT 401(K) PLAN
                           (Full title of the plan)

                                 WAYNE M. ROSE
                               QUANEX CORPORATION
                        1900 WEST LOOP SOUTH, SUITE 1500
                              HOUSTON, TEXAS 77027
                    (Name and address of agent for service)

                                 (713) 961-4600
         (Telephone number, including area code, of agent for service)

                    -------------------------------------

                                 With Copy to:

                             Harva R. Dockery, Esq.
                          Fulbright & Jaworski L.L.P.
                           1301 McKinney, Suite 5100
                           Houston, Texas 77010-3095
                                 (713) 651-5151

                       ---------------------------------

                        CALCULATION OF REGISTRATION FEE
<TABLE>
<CAPTION>
====================================================================================================================================
                                                                   Proposed maximum        Proposed maximum        Amount of
                                              Amount to be        offering price per      aggregate offering      registration
  Title of securities to be registered        registered               share(2)                price(2)               fee
 <S>                                        <C>                          <C>                  <C>                    <C>
------------------------------------------------------------------------------------------------------------------------------------
 Common Stock, $.50 par value  . . . . . .  25,000 shares(1)             $26.69               $667,250               $203  
------------------------------------------------------------------------------------------------------------------------------------
 Rights to purchase shares of Series A
 Junior Participating Preferred Stock  . .     25,000(1) 
====================================================================================================================================
</TABLE>

(1)      Estimated number of shares of Common Stock and accompanying Rights
         that could be purchased with the participant contributions, based upon
         the price of the Common Stock set forth herein.

(2)      Estimated solely for the purpose of calculating the registration fee
         pursuant to Rule 457(c) under the Securities Act of 1933 and based
         upon the average of the high and low sales prices of a share of Common
         Stock as reported by the New York Stock Exchange, Inc. on March 3,
         1997.

In addition, pursuant to Rule 416(c) under the Securities Act of 1933, this
Registration Statement also covers an indeterminate amount of interests to be
offered or sold pursuant to the Piper Impact 401(k) Plan described herein.

================================================================================




<PAGE>   2
                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


ITEM 3.     INCORPORATION OF DOCUMENTS BY REFERENCE.

            Quanex Corporation, a Delaware corporation (the "Company" or
"Registrant"), and the Piper Impact 401(k) Plan (the "Plan") incorporate by
reference in this Registration Statement the following documents:

            1.      The Registrant's Annual Report on Form 10-K for the fiscal
year ended October 31, 1996, and the Plan's latest annual report filed pursuant
to Section 13(a) or 15(d) of the Securities Exchange Act of 1934;

            2.      All other reports filed by the Registrant and the Plan
pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934 since
October 31, 1996;

            3.      The description of the Registrant's common stock, $.50 par
value (the "Common Stock"), contained in the Prospectus dated January 12, 1981,
included in the Registrant's Registration Statement (Registration No. 2-70313)
and filed with the Securities and Exchange Commission pursuant to Rule 424(b)
of the Securities Act of 1933; and

            4.      The description of the rights to purchase Series A Junior
Participating Preferred Stock (the "Rights") set forth in the Amended and
Restated Certificate of Designation, Preferences and Rights, filed as Exhibit 1
to Amendment No. 1 to the Registrant's Form 8-A dated April 28, 1989.

            All documents filed by the Registrant or the Plan pursuant to
Sections 13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934
subsequent to the date of the filing hereof and prior to the filing of a
post-effective amendment which indicates that all securities offered have been
sold or which deregisters all securities then remaining unsold, shall be deemed
to be incorporated by reference in this Registration Statement and to be a part
hereof from the date of filing of such documents.


ITEM 4.     DESCRIPTION OF SECURITIES.

            Not applicable.

ITEM 5.     INTERESTS OF NAMED EXPERTS AND COUNSEL.

            Not applicable.

ITEM 6.     INDEMNIFICATION OF DIRECTORS AND OFFICERS.

            Section 145 of the General Corporation Law of the State of Delaware
provides that a corporation has the power to indemnify a director, officer,
employee or agent of the corporation and certain other persons serving at the
request of the corporation in related capacities against amounts paid and
expenses incurred in connection with an action or proceeding to which he is, or
is threatened to be made, a party by reason of




                                     II-1

<PAGE>   3
ITEM 8.     EXHIBITS.

            4.1     Restated Certificate of Incorporation of the Registrant, as
                    amended on February 27, 1997.

            4.2     Amended and Restated Bylaws of the Registrant, as amended
                    through December 12, 1996, filed as Exhibit 3.2 to the
                    Registrant's Annual Report on Form 10-K for the fiscal year
                    ended October 31, 1996, and incorporated herein by
                    reference.

            4.3     Form of Registrant's Common Stock certificate, filed as
                    Exhibit 4.1 to the Registrant's Quarterly Report on Form
                    10-Q for the quarter ended April 30, 1987, and incorporated
                    herein by reference.

            4.4     Amended and Restated Rights Agreement between the
                    Registrant and Manufacturers Hanover Trust Company, as
                    Rights Agent, filed as Exhibit 1 to Amendment No. 1 to the
                    Registrant's Form 8-A dated April 28, 1989, and
                    incorporated herein by reference.

            4.5     Amended and Restated Certificate of Designation,
                    Preferences and Rights of the Registrant's Series A Junior
                    Participating Preferred Stock, filed as Exhibit 1 to
                    Amendment No. 1 to the Registrant's Form 8-A dated April
                    28, 1989, and incorporated herein by reference.

            4.6     Form of Indenture relating to the Registrant's 6.88%
                    Cumulative Subordinated Debentures due 2007 between the
                    Registrant and Chemical Bank, as Trustee, filed as Exhibit
                    19.2 to the Registrant's Quarterly Report on Form 10-Q for
                    the quarter ended April 30, 1992, and incorporated herein
                    by reference.

            4.7     $250,000,000 Revolving Credit and Term Loan Agreement dated
                    as of July 23, 1996, among the Registrant, Comerica Bank,
                    as Agent, and Harris Trust and Savings Bank and Wells Fargo
                    Bank (Texas), N.A., as Co-Agents, filed as Exhibit 4.1 to
                    the Registrant's Report on Form 8-K, dated August 9, 1996,
                    and incorporated herein by reference.

            4.8     Piper Impact 401(k) Plan.

            4.9     Form of Trust Agreement between Piper Impact, Inc. and
                    Fidelity Management Trust Company dated as of March 5, 1997.

            23.1    Consent of Deloitte & Touche LLP.

            24.1    Powers of Attorney (contained on pages II-6 and II-7
                    hereof).





                                      II-3


<PAGE>   4


            The Registrant hereby undertakes to submit the Plan, and any
amendments thereto, to the Internal Revenue Service ("IRS") in a timely manner
and will make all changes required by the IRS in order to qualify the Plan.

            As permitted by Item 601(b)(4)(iii)(A) of Regulation S-K, the
Registrant has not filed with this Registration Statement certain instruments
defining the rights of holders of long-term debt of the Registrant and its
subsidiaries because the total amount of securities authorized under any of
such instruments does not exceed 10% of the total assets of the Registrant and
its subsidiaries on a consolidated basis. The Registrant agrees to furnish a
copy of any such agreements to the Securities and Exchange Commission upon
request.


ITEM 9.     UNDERTAKINGS.

            The undersigned Registrant hereby undertakes:

            (1)     To file, during any period in which offers or sales are
being made, a post-effective amendment to this Registration Statement:

            (i)     To include any prospectus required by Section 10(a)(3) of
the Securities Act of 1933;

            (ii)    To reflect in the prospectus any facts or events arising
after the effective date of this Registration Statement (or the most recent
post-effective amendment hereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in this
Registration Statement.  Notwithstanding the foregoing, any increase or
decrease in volume of securities offered (if the total dollar volume of
securities offered would not exceed that which was registered) and any
deviation from the low or high end of the estimated maximum offering range may
be reflected in the form of prospectus filed with the Securities and Exchange
Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume
and price represent no more than a 20% change in the maximum aggregate offering
price set forth in the "Calculation of Registration Fee" table in the effective
registration statement; and

            (iii)   To include any material information with respect to the
plan of distribution not previously disclosed in this Registration Statement or
any material change to such information in this Registration Statement;

            Provided, however, that paragraphs (1)(i) and (1)(ii) do not apply
if the information required to be included in a post-effective amendment by
those paragraphs is contained in periodic reports filed with or furnished to
the Securities and Exchange Commission by the Registrant pursuant to Section 13
or Section 15(d) of the Securities Exchange Act of 1934 that are incorporated
by reference in this Registration Statement.

            (2)     That, for the purpose of determining any liability under
the Securities Act of 1933, each such post-effective amendment shall be deemed
to be a new registration statement relating to the securities offered herein,
and the offering of such securities at that time shall be deemed to be the
initial bona fide offering thereof.





                                      II-4


<PAGE>   5

            (3)     To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

            The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Securities Exchange Act of 1934 and each filing of an employee benefit plan's
annual report pursuant to Section 15(d) of the Securities Exchange Act of 1934
that is incorporated by reference in this Registration Statement shall be
deemed to be a new registration statement relating to the securities offered
herein, and the offering of such securities at that time shall be deemed to be
the initial bona fide offering thereof.

            Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the Registrant pursuant to the foregoing provisions, or otherwise,
the Registrant has been advised that in the opinion of the Securities and
Exchange Commission such indemnification is against public policy as expressed
in the Securities Act of 1933 and is, therefore, unenforceable.  In the event
that a claim for indemnification against such liabilities (other than the
payment by the Registrant of expenses incurred or paid by a director, officer
or controlling person of the Registrant in the successful defense of any
action, suit or proceeding) is asserted by such director, officer or
controlling person in connection with the securities being registered, the
Registrant will, unless in the opinion of its counsel the matter has been
settled by controlling precedent, submit to a court of appropriate jurisdiction
the question whether such indemnification by it is against public policy as
expressed in the Securities Act of 1933 and will be governed by the final
adjudication of such issue.





                                      II-5




<PAGE>   6
                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has reasonable grounds to believe that it meets
all of the requirements for filing on Form S-8 and has duly caused this
Registration Statement to be signed on its behalf by the undersigned, thereunto
duly authorized, in the City of Houston, State of Texas, on February 27, 1997.



                                        QUANEX CORPORATION



                                        By:  /s/ VERNON E. OECHSLE            
                                           --------------------------------
                                                 Vernon E. Oechsle
                                              Director, President and
                                              Chief Executive Officer
                                            (Principal Executive Officer)



                               POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS, that each person whose signature
appears below constitutes and appoints Robert C. Snyder, Vernon E. Oechsle and
Wayne M. Rose, and each of them, either one of whom may act without joinder of
the other, his true and lawful attorneys-in-fact and agents, with full power of
substitution and resubstitution, for him and in his name, place and stead, in
any and all capacities, to sign any or all amendments (including post-effective
amendments) to this Registration Statement, and to file the same, with all
exhibits thereto and other documents in connection therewith, with the
Securities and Exchange Commission, granting unto said attorneys-in-fact and
agents, and each of them, full power and authority to do and perform each and
every act and thing requisite and necessary to be done, as fully to all intents
and purposes as he might or could do in person, hereby ratifying and confirming
all that said attorneys-in-fact and agents, and each of them, or the substitute
or substitutes of any or all of them, may lawfully do or cause to be done by
virtue hereof.

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the dates indicated.

<TABLE>
<CAPTION>
        Signature                                  Title                          Date
        ---------                                  -----                          ----
<S>                                         <C>                               <C>
/s/ ROBERT C. SNYDER                             Director and                 February 27, 1997
--------------------------------              Chairman of the Board                              
    Robert C. Snyder                                                    
                                                                        
/s/ VERNON E. OECHSLE                      Director, President and            February 27, 1997
--------------------------------             Chief Executive Officer                             
    Vernon E. Oechsle                     (Principal Executive Officer) 
                                                                        
/s/ JAMES H. DAVIS                      Executive Vice President and          February 27, 1997
--------------------------------            Chief Operating Officer                              
    James H. Davis                        (Principal Operating Officer)  
                                                                         
</TABLE>                                                                


<PAGE>   7
<TABLE>
<S>                                         <C>                                     <C>
/s/ CARL E. PFEIFFER                                  Director                      February 27, 1997 
--------------------------------                                                                      
    Carl E. Pfeiffer                                                                                  
                                                                                                      
                                                                                                      
/s/ GERALD B. HAECKEL                                 Director                      February 27, 1997 
--------------------------------                                                                      
    Gerald B. Haeckel                                                                                 
                                                                                                      
                                                                                                      
                                                                                                      
/s/ JOHN D. O'CONNELL                                 Director                      February 27, 1997 
--------------------------------                                                                      
    John D. O'Connell                                                                                 
                                                                                                      
                                                                                                      
/s/ DONALD G. BARGER, JR.                             Director                      February 27, 1997 
--------------------------------                                                                    
    Donald G. Barger, Jr.                                                                             
                                                                                                      
                                                                                                      
                                                                                                      
/s/ VINCENT R. SCORSONE                               Director                      February 27, 1997 
--------------------------------                                                                    
    Vincent R. Scorsone                                                                               
                                                                                                      
                                                                                                      
                                                                                                      
/s/ MICHAEL J. SEBASTIAN                              Director                      February 27, 1997 
--------------------------------                                                                    
    Michael J. Sebastian                                                                              
                                                                                                      
                                                                                                      
/s/ WAYNE M. ROSE                            Vice President-Finance and             February 27, 1997 
--------------------------------              Chief Financial Officer                                 
    Wayne M. Rose                           (Principal Financial Officer)                             
                                                                                                      
                                                                                                      
                                                                                                      
/s/ VIREN M. PARIKH                                   Controller                    February 27, 1997 
--------------------------------            (Principal Accounting Officer)                          
    Viren M. Parikh                                                       
</TABLE>





                                      II-7





<PAGE>   8

         The Plan.  Pursuant to the requirements of the Securities Act of 1933,
the Administrative Committee of the Plan has duly caused this Registration
Statement to be signed on its behalf by the undersigned members of such
committee, thereunto duly authorized, in the City of Houston, State of Texas,
on February 27, 1997.



                                      PIPER IMPACT 401(k) PLAN                 
                                                                               
                                                                               
                                                                               
                                      By: /s/ VERNON E. OECHSLE                
                                         --------------------------------------
                                              Vernon E. Oechsle                 
                                                                               
                                                                               
                                                                               
                                      By: /s/ JAMES H. DAVIS                   
                                         --------------------------------------
                                              James H. Davis                   
                                                                               
                                                                                
                                                                                
                                      By: /s/ WAYNE M. ROSE                    
                                         --------------------------------------
                                              Wayne M. Rose                    
                                                                               
                                                                               
                                                                                
                                      By: /s/ JOSEPH K. PEERY                  
                                         --------------------------------------
                                              Joseph K. Peery                  
                                                                               




                                      II-8

                                          
<PAGE>   9

                                 EXHIBIT INDEX


<TABLE>
<CAPTION>
      Exhibit Number                                   Description                                   
      --------------                     ----------------------------------------                 
<S>                        <C>                                                                     
           4.1             Restated Certificate of Incorporation of the Registrant, as amended
                           on February 27, 1997.

           4.2             Amended  and Restated Bylaws of the  Registrant, as amended through
                           December 12, 1996, filed as Exhibit 3.2 to the Registrant's  Annual
                           Report on Form 10-K for the fiscal year ended October 31, 1996, and
                           incorporated herein by reference.

           4.3             Form of Registrant's Common Stock certificate, filed as Exhibit 4.1
                           to the  Registrant's Quarterly Report on  Form 10-Q for the quarter
                           ended April 30, 1987, and incorporated herein by reference.

           4.4             Amended and  Restated Rights  Agreement between  the Registrant and
                           Manufacturers  Hanover Trust  Company,  as Rights  Agent,  filed as
                           Exhibit 1  to Amendment  No. 1 to  the Registrant's  Form 8-A dated
                           April 28, 1989, and incorporated herein by reference.

           4.5             Amended and  Restated Certificate  of Designation,  Preferences and
                           Rights of the Registrant's Series A Junior Participating  Preferred
                           Stock,  filed as Exhibit 1 to  Amendment No. 1  to the Registrant's
                           Form 8-A  dated   April 28,  1989,   and  incorporated  herein   by
                           reference.

           4.6             Form  of Indenture  relating to  the Registrant's  6.88% Cumulative
                           Subordinated  Debentures  due  2007  between  the  Registrant   and
                           Chemical   Bank,  as   Trustee,  filed   as  Exhibit 19.2   to  the
                           Registrant's Quarterly  Report on  Form 10-Q for  the quarter ended
                           April 30, 1992, and incorporated herein by reference.

           4.7             $250,000,000 Revolving Credit and  Term Loan Agreement dated as  of
                           July 23, 1996,  among the Registrant, Comerica Bank, as  Agent, and
                           Harris Trust and  Savings Bank and Wells Fargo Bank  (Texas), N.A.,
                           as  Co-Agents, filed as  Exhibit 4.1 to the  Registrant's Report on
                           Form 8-K,  dated  August   9,  1996,  and  incorporated  herein  by
                           reference.

           4.8             Piper Impact 401(k) Plan.

           4.9             Form  of  Trust  Agreement  between Piper Impact, Inc. and Fidelity 
                           Management   Trust   Company   dated  as   of    March   5,   1997.

           23.1            Consent of Deloitte & Touche LLP.

</TABLE>

<PAGE>   10
           24.1            Powers of Attorney (contained on pages II-6 and II-7
                           hereof).


           As permitted by Item 601(b)(4)(iii)(A) of Regulation S-K, the
Registrant has not filed with this Registration Statement certain instruments
defining the rights of holders of long-term debt of the Registrant and its
subsidiaries because the total amount of securities authorized under any of such
instruments does not exceed 10% of the total assets of the Registrant and its
subsidiaries on a consolidated basis. The Registrant agrees to furnish a copy of
any such agreements to the Securities and Exchange Commission upon request.
[{"type": "S-8", "sequence": "1", "description": "QUANEX CORPORATION", "secsgml_size_bytes": 29337}]
{"company-data": {"conformed-name": "QUANEX CORP", "cik": "0000276889", "assigned-sic": "3312", "irs-number": "381872178", "state-of-incorporation": "DE", "fiscal-year-end": "1031"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-22977", "film-number": "97552837"}, "business-address": {"street1": "1900 W LOOP SOUTH STE 1500", "street2": "ATTN THOMAS M BEWLEY", "city": "HOUSTON", "state": "TX", "zip": "77027", "phone": "7139614600"}, "mail-address": {"street1": "1900 WEST LOOP SOUTH", "street2": "SUITE 1500", "city": "HOUSTON", "state": "TX", "zip": "77027"}}
1

    As filed with the Securities and Exchange Commission on March 7, 1997
                                                     Registration No. 333-______

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                                        
                        --------------------------------

                                    FORM S-8

            REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

                       -------------------------------

                               QUANEX CORPORATION
             (Exact name of registrant as specified in its charter)

      DELAWARE                                        38-1872178
(State or other jurisdiction of                      (I.R.S Employer
incorporation or organization)                       Identification No.)

1900 WEST LOOP SOUTH, SUITE 1500
     HOUSTON, TEXAS                                       77027
(Address of Principal Executive Offices)                (Zip Code)
                      

                           PIPER IMPACT 401(K) PLAN
                           (Full title of the plan)

                                 WAYNE M. ROSE
                               QUANEX CORPORATION
                        1900 WEST LOOP SOUTH, SUITE 1500
                              HOUSTON, TEXAS 77027
                    (Name and address of agent for service)

                                 (713) 961-4600
         (Telephone number, including area code, of agent for service)

                    -------------------------------------

                                 With Copy to:

                             Harva R. Dockery, Esq.
                          Fulbright & Jaworski L.L.P.
                           1301 McKinney, Suite 5100
                           Houston, Texas 77010-3095
                                 (713) 651-5151

                       ---------------------------------

                        CALCULATION OF REGISTRATION FEE
====================================================================================================================================
                                                                   Proposed maximum        Proposed maximum        Amount of
                                              Amount to be        offering price per      aggregate offering      registration
  Title of securities to be registered        registered               share(2)                price(2)               fee
------------------------------------------------------------------------------------------------------------------------------------
 Common Stock, $.50 par value  . . . . . .  25,000 shares(1)             $26.69               $667,250               $203  
------------------------------------------------------------------------------------------------------------------------------------
 Rights to purchase shares of Series A
 Junior Participating Preferred Stock  . .     25,000(1) 
====================================================================================================================================
(1)      Estimated number of shares of Common Stock and accompanying Rights
         that could be purchased with the participant contributions, based upon
         the price of the Common Stock set forth herein.

(2)      Estimated solely for the purpose of calculating the registration fee
         pursuant to Rule 457(c) under the Securities Act of 1933 and based
         upon the average of the high and low sales prices of a share of Common
         Stock as reported by the New York Stock Exchange, Inc. on March 3,
         1997.

In addition, pursuant to Rule 416(c) under the Securities Act of 1933, this
Registration Statement also covers an indeterminate amount of interests to be
offered or sold pursuant to the Piper Impact 401(k) Plan described herein.

================================================================================
2
                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.     INCORPORATION OF DOCUMENTS BY REFERENCE.

            Quanex Corporation, a Delaware corporation (the "Company" or
"Registrant"), and the Piper Impact 401(k) Plan (the "Plan") incorporate by
reference in this Registration Statement the following documents:

            1.      The Registrant's Annual Report on Form 10-K for the fiscal
year ended October 31, 1996, and the Plan's latest annual report filed pursuant
to Section 13(a) or 15(d) of the Securities Exchange Act of 1934;

            2.      All other reports filed by the Registrant and the Plan
pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934 since
October 31, 1996;

            3.      The description of the Registrant's common stock, $.50 par
value (the "Common Stock"), contained in the Prospectus dated January 12, 1981,
included in the Registrant's Registration Statement (Registration No. 2-70313)
and filed with the Securities and Exchange Commission pursuant to Rule 424(b)
of the Securities Act of 1933; and

            4.      The description of the rights to purchase Series A Junior
Participating Preferred Stock (the "Rights") set forth in the Amended and
Restated Certificate of Designation, Preferences and Rights, filed as Exhibit 1
to Amendment No. 1 to the Registrant's Form 8-A dated April 28, 1989.

            All documents filed by the Registrant or the Plan pursuant to
Sections 13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934
subsequent to the date of the filing hereof and prior to the filing of a
post-effective amendment which indicates that all securities offered have been
sold or which deregisters all securities then remaining unsold, shall be deemed
to be incorporated by reference in this Registration Statement and to be a part
hereof from the date of filing of such documents.

ITEM 4.     DESCRIPTION OF SECURITIES.

            Not applicable.

ITEM 5.     INTERESTS OF NAMED EXPERTS AND COUNSEL.

            Not applicable.

ITEM 6.     INDEMNIFICATION OF DIRECTORS AND OFFICERS.

            Section 145 of the General Corporation Law of the State of Delaware
provides that a corporation has the power to indemnify a director, officer,
employee or agent of the corporation and certain other persons serving at the
request of the corporation in related capacities against amounts paid and
expenses incurred in connection with an action or proceeding to which he is, or
is threatened to be made, a party by reason of

                                     II-1
3
ITEM 8.     EXHIBITS.

            4.1     Restated Certificate of Incorporation of the Registrant, as
                    amended on February 27, 1997.

            4.2     Amended and Restated Bylaws of the Registrant, as amended
                    through December 12, 1996, filed as Exhibit 3.2 to the
                    Registrant's Annual Report on Form 10-K for the fiscal year
                    ended October 31, 1996, and incorporated herein by
                    reference.

            4.3     Form of Registrant's Common Stock certificate, filed as
                    Exhibit 4.1 to the Registrant's Quarterly Report on Form
                    10-Q for the quarter ended April 30, 1987, and incorporated
                    herein by reference.

            4.4     Amended and Restated Rights Agreement between the
                    Registrant and Manufacturers Hanover Trust Company, as
                    Rights Agent, filed as Exhibit 1 to Amendment No. 1 to the
                    Registrant's Form 8-A dated April 28, 1989, and
                    incorporated herein by reference.

            4.5     Amended and Restated Certificate of Designation,
                    Preferences and Rights of the Registrant's Series A Junior
                    Participating Preferred Stock, filed as Exhibit 1 to
                    Amendment No. 1 to the Registrant's Form 8-A dated April
                    28, 1989, and incorporated herein by reference.

            4.6     Form of Indenture relating to the Registrant's 6.88%
                    Cumulative Subordinated Debentures due 2007 between the
                    Registrant and Chemical Bank, as Trustee, filed as Exhibit
                    19.2 to the Registrant's Quarterly Report on Form 10-Q for
                    the quarter ended April 30, 1992, and incorporated herein
                    by reference.

            4.7     $250,000,000 Revolving Credit and Term Loan Agreement dated
                    as of July 23, 1996, among the Registrant, Comerica Bank,
                    as Agent, and Harris Trust and Savings Bank and Wells Fargo
                    Bank (Texas), N.A., as Co-Agents, filed as Exhibit 4.1 to
                    the Registrant's Report on Form 8-K, dated August 9, 1996,
                    and incorporated herein by reference.

            4.8     Piper Impact 401(k) Plan.

            4.9     Form of Trust Agreement between Piper Impact, Inc. and
                    Fidelity Management Trust Company dated as of March 5, 1997.

            23.1    Consent of Deloitte & Touche LLP.

            24.1    Powers of Attorney (contained on pages II-6 and II-7
                    hereof).

                                      II-3
4

            The Registrant hereby undertakes to submit the Plan, and any
amendments thereto, to the Internal Revenue Service ("IRS") in a timely manner
and will make all changes required by the IRS in order to qualify the Plan.

            As permitted by Item 601(b)(4)(iii)(A) of Regulation S-K, the
Registrant has not filed with this Registration Statement certain instruments
defining the rights of holders of long-term debt of the Registrant and its
subsidiaries because the total amount of securities authorized under any of
such instruments does not exceed 10% of the total assets of the Registrant and
its subsidiaries on a consolidated basis. The Registrant agrees to furnish a
copy of any such agreements to the Securities and Exchange Commission upon
request.

ITEM 9.     UNDERTAKINGS.

            The undersigned Registrant hereby undertakes:

            (1)     To file, during any period in which offers or sales are
being made, a post-effective amendment to this Registration Statement:

            (i)     To include any prospectus required by Section 10(a)(3) of
the Securities Act of 1933;

            (ii)    To reflect in the prospectus any facts or events arising
after the effective date of this Registration Statement (or the most recent
post-effective amendment hereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in this
Registration Statement.  Notwithstanding the foregoing, any increase or
decrease in volume of securities offered (if the total dollar volume of
securities offered would not exceed that which was registered) and any
deviation from the low or high end of the estimated maximum offering range may
be reflected in the form of prospectus filed with the Securities and Exchange
Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume
and price represent no more than a 20% change in the maximum aggregate offering
price set forth in the "Calculation of Registration Fee" table in the effective
registration statement; and

            (iii)   To include any material information with respect to the
plan of distribution not previously disclosed in this Registration Statement or
any material change to such information in this Registration Statement;

            Provided, however, that paragraphs (1)(i) and (1)(ii) do not apply
if the information required to be included in a post-effective amendment by
those paragraphs is contained in periodic reports filed with or furnished to
the Securities and Exchange Commission by the Registrant pursuant to Section 13
or Section 15(d) of the Securities Exchange Act of 1934 that are incorporated
by reference in this Registration Statement.

            (2)     That, for the purpose of determining any liability under
the Securities Act of 1933, each such post-effective amendment shall be deemed
to be a new registration statement relating to the securities offered herein,
and the offering of such securities at that time shall be deemed to be the
initial bona fide offering thereof.

                                      II-4
5

            (3)     To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

            The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Securities Exchange Act of 1934 and each filing of an employee benefit plan's
annual report pursuant to Section 15(d) of the Securities Exchange Act of 1934
that is incorporated by reference in this Registration Statement shall be
deemed to be a new registration statement relating to the securities offered
herein, and the offering of such securities at that time shall be deemed to be
the initial bona fide offering thereof.

            Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the Registrant pursuant to the foregoing provisions, or otherwise,
the Registrant has been advised that in the opinion of the Securities and
Exchange Commission such indemnification is against public policy as expressed
in the Securities Act of 1933 and is, therefore, unenforceable.  In the event
that a claim for indemnification against such liabilities (other than the
payment by the Registrant of expenses incurred or paid by a director, officer
or controlling person of the Registrant in the successful defense of any
action, suit or proceeding) is asserted by such director, officer or
controlling person in connection with the securities being registered, the
Registrant will, unless in the opinion of its counsel the matter has been
settled by controlling precedent, submit to a court of appropriate jurisdiction
the question whether such indemnification by it is against public policy as
expressed in the Securities Act of 1933 and will be governed by the final
adjudication of such issue.

                                      II-5
6
                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has reasonable grounds to believe that it meets
all of the requirements for filing on Form S-8 and has duly caused this
Registration Statement to be signed on its behalf by the undersigned, thereunto
duly authorized, in the City of Houston, State of Texas, on February 27, 1997.

                                        QUANEX CORPORATION

                                        By:  /s/ VERNON E. OECHSLE            
                                           --------------------------------
                                                 Vernon E. Oechsle
                                              Director, President and
                                              Chief Executive Officer
                                            (Principal Executive Officer)

                               POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS, that each person whose signature
appears below constitutes and appoints Robert C. Snyder, Vernon E. Oechsle and
Wayne M. Rose, and each of them, either one of whom may act without joinder of
the other, his true and lawful attorneys-in-fact and agents, with full power of
substitution and resubstitution, for him and in his name, place and stead, in
any and all capacities, to sign any or all amendments (including post-effective
amendments) to this Registration Statement, and to file the same, with all
exhibits thereto and other documents in connection therewith, with the
Securities and Exchange Commission, granting unto said attorneys-in-fact and
agents, and each of them, full power and authority to do and perform each and
every act and thing requisite and necessary to be done, as fully to all intents
and purposes as he might or could do in person, hereby ratifying and confirming
all that said attorneys-in-fact and agents, and each of them, or the substitute
or substitutes of any or all of them, may lawfully do or cause to be done by
virtue hereof.

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the dates indicated.
Signature                                  Title                          Date
        ---------                                  -----                          ----
/s/ ROBERT C. SNYDER                             Director and                 February 27, 1997
--------------------------------              Chairman of the Board                              
    Robert C. Snyder                                                    
                                                                        
/s/ VERNON E. OECHSLE                      Director, President and            February 27, 1997
--------------------------------             Chief Executive Officer                             
    Vernon E. Oechsle                     (Principal Executive Officer) 
                                                                        
/s/ JAMES H. DAVIS                      Executive Vice President and          February 27, 1997
--------------------------------            Chief Operating Officer                              
    James H. Davis                        (Principal Operating Officer)
7
/s/ CARL E. PFEIFFER                                  Director                      February 27, 1997 
--------------------------------                                                                      
    Carl E. Pfeiffer                                                                                  
                                                                                                      
                                                                                                      
/s/ GERALD B. HAECKEL                                 Director                      February 27, 1997 
--------------------------------                                                                      
    Gerald B. Haeckel                                                                                 
                                                                                                      
                                                                                                      
                                                                                                      
/s/ JOHN D. O'CONNELL                                 Director                      February 27, 1997 
--------------------------------                                                                      
    John D. O'Connell                                                                                 
                                                                                                      
                                                                                                      
/s/ DONALD G. BARGER, JR.                             Director                      February 27, 1997 
--------------------------------                                                                    
    Donald G. Barger, Jr.                                                                             
                                                                                                      
                                                                                                      
                                                                                                      
/s/ VINCENT R. SCORSONE                               Director                      February 27, 1997 
--------------------------------                                                                    
    Vincent R. Scorsone                                                                               
                                                                                                      
                                                                                                      
                                                                                                      
/s/ MICHAEL J. SEBASTIAN                              Director                      February 27, 1997 
--------------------------------                                                                    
    Michael J. Sebastian                                                                              
                                                                                                      
                                                                                                      
/s/ WAYNE M. ROSE                            Vice President-Finance and             February 27, 1997 
--------------------------------              Chief Financial Officer                                 
    Wayne M. Rose                           (Principal Financial Officer)                             
                                                                                                      
                                                                                                      
                                                                                                      
/s/ VIREN M. PARIKH                                   Controller                    February 27, 1997 
--------------------------------            (Principal Accounting Officer)                          
    Viren M. Parikh
II-7
8

         The Plan.  Pursuant to the requirements of the Securities Act of 1933,
the Administrative Committee of the Plan has duly caused this Registration
Statement to be signed on its behalf by the undersigned members of such
committee, thereunto duly authorized, in the City of Houston, State of Texas,
on February 27, 1997.

                                      PIPER IMPACT 401(k) PLAN                 
                                                                               
                                                                               
                                                                               
                                      By: /s/ VERNON E. OECHSLE                
                                         --------------------------------------
                                              Vernon E. Oechsle                 
                                                                               
                                                                               
                                                                               
                                      By: /s/ JAMES H. DAVIS                   
                                         --------------------------------------
                                              James H. Davis                   
                                                                               
                                                                                
                                                                                
                                      By: /s/ WAYNE M. ROSE                    
                                         --------------------------------------
                                              Wayne M. Rose                    
                                                                               
                                                                               
                                                                                
                                      By: /s/ JOSEPH K. PEERY                  
                                         --------------------------------------
                                              Joseph K. Peery                  
                                                                               

                                      II-8
9

                                 EXHIBIT INDEX
Exhibit Number                                   Description                                   
      --------------                     ----------------------------------------
4.1             Restated Certificate of Incorporation of the Registrant, as amended
                           on February 27, 1997.

           4.2             Amended  and Restated Bylaws of the  Registrant, as amended through
                           December 12, 1996, filed as Exhibit 3.2 to the Registrant's  Annual
                           Report on Form 10-K for the fiscal year ended October 31, 1996, and
                           incorporated herein by reference.

           4.3             Form of Registrant's Common Stock certificate, filed as Exhibit 4.1
                           to the  Registrant's Quarterly Report on  Form 10-Q for the quarter
                           ended April 30, 1987, and incorporated herein by reference.

           4.4             Amended and  Restated Rights  Agreement between  the Registrant and
                           Manufacturers  Hanover Trust  Company,  as Rights  Agent,  filed as
                           Exhibit 1  to Amendment  No. 1 to  the Registrant's  Form 8-A dated
                           April 28, 1989, and incorporated herein by reference.

           4.5             Amended and  Restated Certificate  of Designation,  Preferences and
                           Rights of the Registrant's Series A Junior Participating  Preferred
                           Stock,  filed as Exhibit 1 to  Amendment No. 1  to the Registrant's
                           Form 8-A  dated   April 28,  1989,   and  incorporated  herein   by
                           reference.

           4.6             Form  of Indenture  relating to  the Registrant's  6.88% Cumulative
                           Subordinated  Debentures  due  2007  between  the  Registrant   and
                           Chemical   Bank,  as   Trustee,  filed   as  Exhibit 19.2   to  the
                           Registrant's Quarterly  Report on  Form 10-Q for  the quarter ended
                           April 30, 1992, and incorporated herein by reference.

           4.7             $250,000,000 Revolving Credit and  Term Loan Agreement dated as  of
                           July 23, 1996,  among the Registrant, Comerica Bank, as  Agent, and
                           Harris Trust and  Savings Bank and Wells Fargo Bank  (Texas), N.A.,
                           as  Co-Agents, filed as  Exhibit 4.1 to the  Registrant's Report on
                           Form 8-K,  dated  August   9,  1996,  and  incorporated  herein  by
                           reference.

           4.8             Piper Impact 401(k) Plan.

           4.9             Form  of  Trust  Agreement  between Piper Impact, Inc. and Fidelity 
                           Management   Trust   Company   dated  as   of    March   5,   1997.

           23.1            Consent of Deloitte & Touche LLP.
10
           24.1            Powers of Attorney (contained on pages II-6 and II-7
                           hereof).

           As permitted by Item 601(b)(4)(iii)(A) of Regulation S-K, the
Registrant has not filed with this Registration Statement certain instruments
defining the rights of holders of long-term debt of the Registrant and its
subsidiaries because the total amount of securities authorized under any of such
instruments does not exceed 10% of the total assets of the Registrant and its
subsidiaries on a consolidated basis. The Registrant agrees to furnish a copy of
any such agreements to the Securities and Exchange Commission upon request.