ATI (ATI) 10-K 2021 FY Annual report

Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the incorporation by reference in the following Registration Statements:

(1) Registration Statements (Form S-3 No. 333-254906) of Allegheny Technologies Incorporated, and

(2) Registration Statements (Form S-8 Nos. 333-238169, 333-203784, 333-217942, 333-188641, 333-145651, 333-59161, 333-10229, and 333-45965) pertaining to the employee benefit plans of Allegheny Technologies Incorporated;

of our reports dated February 25, 2022, with respect to the consolidated financial statements of Allegheny Technologies Incorporated and Subsidiaries and the effectiveness of internal control over financial reporting of Allegheny Technologies Incorporated and Subsidiaries included in this Annual Report (Form 10-K) of Allegheny Technologies Incorporated and Subsidiaries for the year ended December 31, 2021.

/s/ Ernst & Young LLP

Pittsburgh, Pennsylvania

February 25, 2022