Thyssenkrupp Turns Up the Heat: Hot Strip Mill Resumes as Green Steel Project Nears

Thyssenkrupp resumes hot strip mill output after seven-month outage, while advancing a €2B hydrogen-powered decarbonisation plan. Stock climbs 65% from March low.

Thyssenkrupp is navigating a dual narrative: restoring a key production asset after an industrial accident while plotting the most ambitious decarbonisation programme in German steelmaking. The stock, which has already clawed back 65% from its March lows, is betting that both tracks deliver.

Mill restart ends seven-month outage

Trial operations have resumed at the Hot Strip Mill 4 in Duisburg, roughly seven months after a flash fire on 24 October 2025 damaged furnaces and parts of the roof structure. Repairs are now complete, and Thyssenkrupp Steel used the downtime to introduce technical upgrades aimed at improving plant availability and process stability. The associated continuous caster had already returned to service in mid-December.

The hot strip mill is a linchpin of the company's flat-steel production, with a nameplate capacity of 3.1 million tonnes a year. Its walking-beam furnaces can reach 1,300 degrees Celsius and produce hot-rolled flat steel ranging from standard grades to advanced high-strength products for automotive, e-mobility, machinery and energy clients.

The restart is part of a broader €800 million modernisation programme in Duisburg that includes a new continuous caster, the revamped mill with two walking-beam furnaces, and fully automated slab logistics. Full commercial production will follow once the trial phase demonstrates stable operation.

Stock has run ahead of operational milestones

Thyssenkrupp shares traded at €11.71 on Thursday, up more than 21% since the start of the year and roughly 65% above the 52-week low of €7.10 reached at the end of March. The 30-day gain stands at just over 5%. Yet the stock still sits more than 11% below the 52-week high of €13.24 posted in October 2025, suggesting the market has already priced in much of the operational recovery.

Investors are now watching whether the hot strip mill can ramp up smoothly. A stable output from the Duisburg plant would provide tangible evidence that the industrial engine is firing on all cylinders again.

Green steel: the bigger bet

While the mill restart addresses the near term, Thyssenkrupp's longer-term narrative revolves around its "tkH2Steel" programme. The company is building a direct reduction plant in Duisburg that will eventually replace a coal-fired blast furnace. The facility is due to start up in 2026 using natural gas, with a phased switch to hydrogen beginning in 2028.

Once fully hydrogen-powered, the plant could eliminate up to 3.5 million tonnes of CO? annually — equivalent to more than 6% of total emissions from the German steel industry. The federal government and the state of North Rhine-Westphalia have committed roughly €2 billion in subsidies, approved by the European Commission. The ultimate target is climate-neutral steel production by 2045, with a substantial portion achieved as early as 2035.

Alongside the green steel push, Thyssenkrupp is restructuring itself into a financial holding with independent business units. The Decarbon Technologies segment bundles hydrogen, green chemistry and renewables, and the group retains a majority stake in Thyssenkrupp Nucera, an electrolyser specialist for green hydrogen.

Volatility reflects unresolved risks

The transformation is not without hurdles. High energy costs and a still-incomplete hydrogen infrastructure pose real challenges. Whether green steel can compete economically in Germany over the long haul remains a subject of debate. That uncertainty shows up in the share price: annualised volatility stands at around 55%, a figure that will spook risk-averse investors.

The direct reduction plant is set to begin operations this year. If the ramp-up proceeds on schedule, the first hydrogen-produced steel from Duisburg could provide the next major proof point that Thyssenkrupp’s transformation is more than just a roadmap. For now, the market is watching two clocks: the hot strip mill’s return to full output and the countdown to green steel. Both will determine whether the stock can push decisively above the €13 mark.