Thyssenkrupp Steel has resumed trial operations at Hot Strip Mill 4 (HSM 4) in Duisburg, Germany, marking a major recovery milestone after a fire damaged the facility in October 2025. The incident affected furnace systems and parts of the roof structure, prompting extensive repair and modernization work over the past several months.

Beyond restoring the damaged sections, the company implemented targeted technical upgrades to improve operational reliability, process stability, and production efficiency. The associated continuous casting line had already returned to service in December 2025, paving the way for the restart of the hot strip mill. Hot Strip Mill 4 is a key component of Thyssenkrupp Steel's modernization strategy and is designed to manufacture a broad range of hot-rolled flat steel products, including advanced high-strength and premium steel grades used in the automotive, engineering, construction, and energy sectors. The upgraded facility now features enhanced rolling precision, improved surface quality, and greater production flexibility.

The restart strengthens the company's production network in Duisburg and supports its long-term strategy of expanding high-value steel output. Industry observers view the successful recommissioning as an important step in restoring full capacity while enhancing the competitiveness of one of Europe's most advanced steel production hubs.