UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d)

OF THE SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported): June 12, 2015

Graham Corporation

(Exact name of Registrant as specified in its charter)

Registrant’s telephone number, including area code: (585) 343-2216

N/A

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the Registrant under any of the following provisions:

Item 1.01 Entry into a Material Definitive Agreement

On June 12, 2015, Graham Corporation (the “Company”) and its wholly-owned subsidiary Energy Steel & Supply Co. (“Energy Steel”) entered into a Restated Security Agreement (the “Security Agreement”) with Bank of America, N.A. (the “Bank”). The Security Agreement was executed to include the assets of Energy Steel as collateral under that certain Loan Agreement with the Bank dated December 3, 2010 (the “Loan Agreement”). Also on June 12, 2015, Energy Steel executed a Continuing and Unconditional Guarantee of the Company’s obligations under the Loan Agreement.

A copy of the Security Agreement and the Guarantee are attached to this Current Report on Form 8-K as Exhibits 99.1 and 99.2, respectively, and the above summary of the terms of such instruments are qualified in their entirety by reference to their actual text, which is incorporated herein by reference.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this Report to be signed on its behalf by the undersigned hereunto duly authorized.