Joint Ventures	6 Months Ended
Jun. 28, 2026
Equity Method Investments and Joint Ventures [Abstract]
Joint Ventures	Joint Ventures The financial results of majority-owned joint ventures are consolidated into the Company’s operating results and financial position, with the minority ownership interest recognized in the consolidated statements of operations as net income attributable to noncontrolling interests, and as equity attributable to the noncontrolling interests within total stockholders’ equity. Majority-Owned Joint Venture STAL: The Company has a 60% interest in the Chinese joint venture known as STAL. The remaining 40% interest in STAL is owned by China Baowu Steel Group Corporation Limited, a state authorized investment company whose equity securities are publicly traded in the People’s Republic of China. STAL is part of ATI’s AA&S segment and manufactures Precision Rolled Strip (PRS) stainless products mainly for the electronics and automotive markets located in Asia. Cash and cash equivalents held by STAL as of June 28, 2026 and December 28, 2025 were $102.3 million and $97.6 million, respectively.

Joint Ventures

6 Months Ended

Jun. 28, 2026

Equity Method Investments and Joint Ventures [Abstract]

The financial results of majority-owned joint ventures are consolidated into the Company’s operating results and financial position, with the minority ownership interest recognized in the consolidated statements of operations as net income attributable to noncontrolling interests, and as equity attributable to the noncontrolling interests within total stockholders’ equity.

Majority-Owned Joint Venture

STAL:

The Company has a 60% interest in the Chinese joint venture known as STAL. The remaining 40% interest in STAL is owned by China Baowu Steel Group Corporation Limited, a state authorized investment company whose equity securities are publicly traded in the People’s Republic of China. STAL is part of ATI’s AA&S segment and manufactures Precision Rolled Strip

(PRS) stainless products mainly for the electronics and automotive markets located in Asia. Cash and cash equivalents held by STAL as of June 28, 2026 and December 28, 2025 were $102.3 million and $97.6 million, respectively.