Exhibit 23.1
Consent of Independent Registered Public Accounting Firm
We consent to the incorporation by reference in the Registration Statement (Form S-8 No.
333-145651) pertaining to the Rome Metals, LLC Employees 401(k) and Profit Sharing Plan of our
report dated June 25, 2009, with respect to the financial statements and schedule of the Rome
Metals, LLC Employees 401(k) and Profit Sharing Plan included in this Annual Report (Form 11-K)
for the year ended December 31, 2008.
/s/ Ernst & Young LLP
Pittsburgh, Pennsylvania
June 25, 2009