Our customer Salzgitter Flachstahl is a significant player in the steel industry. Committed to sustainability and innovation, they are a high-quality steel producer in Europe. But they’re still aiming high, with ambitious goals in key strategic markets. To get there, they looked to SMS group and our technology to build a state-of-the-art hot dip galvanizing line in Salzgitter. This was no ordinary project for the company. They were looking for a leading-edge line that would keep pace with the ever-evolving demands on materials from products and markets for the coming decades while meeting Salzgitter’s high standards for environmental performance – the new line incorporates several sustainability features, such as a waste heat recovery system, which captures and reuses energy generated during the annealing and galvanizing process. Salzgitter’s financial commitment to this project reflects its ambitious goals. The hot dip galvanizing line no. 3 project (FV3) is the single largest investment Salzgitter Group has made in the last ten years.
The opportunity
So where are these new and sophisticated grades of steel primarily needed? A major chunk of the opportunity for these materials comes from the automotive sector. The industry continues to grow and has an increased demand for galvanized steel because of a focus on lighter weight, improved fuel efficiency, and the increasing focus on battery-electric-vehicles, as well as the need for greater safety and durability. Its latest body-in-white components require high-strength and ultra-high-strength steel grades such as micro-alloyed steels, dual-phase steels, and multiphase steels with stringent requirements for reliable surface quality. In addition to the automotive industry, Salzgitter identified other growth opportunities in the household appliance and construction industries.
Galvanized steel is base material for the manufacturing of a wide range of products like refrigerators, washing machines, and ovens. The new line’s ability to produce high-quality, durable galvanized
steel will meet and exceed the needs of this industry and help grow Salzgitter’s customer base in this sector.
Evolution built-in: the technology
The new hot dip line is perfect for higher-strength steels. It supports enhanced formability and, therefore, more complex component geometries – all vital criteria for the materials that will be in demand as Salzgitter’s customers continue to innovate. To achieve the required product properties, Salzgitter relies entirely on SMS group technology. In addition to the design and production of the mechanical equipment and the complete electrics and automation package, the furnace and process technology were a decisive part of the SMS group scope. Several key technologies stand out in that respect:
- Drever annealing technology: To manufacture advanced high-strength, multiphase, and complex phase steel grades with tensile strengths of up to and greater than 1,000 MPa exceptional cooling performance is required. The Drever ultra-fast cooling system for ultra high-strength steel grades delivers unmatched cooling rates of more than 200 K/s per 1 mm strip thickness. It does so by taking advantage of hydrogen’s low density, high thermal conductivity properties. The unique feature of the patented ultra-fast cooling system is the addition of pure hydrogen (instead of a state-of-the-art nitrogen-hydrogen-mixture) directly into the cooling chamber, pushing the hydrogen content up to 50 %to achieve enhanced cooling performance without extra hydrogen demand in the other furnace areas.
- PrOBOX® technology: Depending on the alloying concept used, surface oxides can diminish the adhesion of the metal coating. Full wettability by molten zinc is challenging, especially for the steel compositions required for ultra high-strength steel grades. To ensure the highest possible surface quality, the annealing furnace is equipped with our PrOBOX® technology for pre-oxidation. The controlled infusion of air into the PrOBOX® chamber creates a closed iron-oxide layer on the surface. This barrier suppresses the silicon and manganese migration to the surface, which otherwise would lead to the production of their oxides at the surface preventing wettability by molten zinc. The thickness of the oxide layer produced is mainly influenced by temperature. The tight control of the PrOBOX® technology for pre-oxidation facilitates galvanizing high-alloyed high-strength steel grades eliminating zinc wettability issues.
- Air-knife: The Duma-Bandzink air-knife system achieves optimal setting of the coating uniformity and a high surface quality. To that end, the air-knife system is equipped with opti-mized components and new constituents that enhance product quality and productivity and reduce the consumption of zinc and energy.
Partnership: the critical success factor
On paper, SMS group and Salzgitter Flachstahl were already ideal partners. SMS group brought the ability to create and realize complex technological solutions to the table. Salzgitter adds the experience of successfully operating complex strip processing lines and succeeding in a competitive market environment with sophisticated products. But the project leadership from both companies recognized that more than expertise, know-how, and talent was needed to drive a pioneering and ambitious project like this over the finish line.
The goal was to be solution driven as a team.
Michael Brühl, Director of Cold Rolled Flat Products at Salzgitter Flachstahl, and Holger Behrens, Executive Vice President of Flat Products at SMS group, talk openly about what counts. Mr. Brühl points out the importance of total transparency: ”It’s especially important when there are disagreements and things are not going perfectly. We made sure that everybody on the team knew it was not just ok to say when they didn’t have a solution to a problem – it was expected. We would then take the problem to the next level of management of expertise, work on it, find a solution, and feed it back to the teams, all the while keeping them moving and productive.“ Holger Behrens adds: ”For that to happen, you need an atmosphere of trust. We did that by creating open communication channels on all team levels, where everybody could bring up critical issues or challenges at any time. The goal was to be solution driven as a team – you can only do that when everyone is aware of the obstacles and discusses them openly. Trust is a crucial success factor.”