The measurements on the caster were performed using HD moldFO and FEM calculations. The HD moldFO, which is equipped with optical fibers, was used to evaluate the local temperatures and the heat flux density in the copper mold. Likewise, the overall geometry and roughness of the mold plate were measured during the trials in order to evaluate the influence on the wear of the mold plate.
In order to counteract the loads on the copper plate in a targeted manner, Tata Steel in IJmuiden, together with SMS group, tested a mold plate completely nickel-coated. The aim is to reduce the thermal and mechanical loads on the mold. A promising solution is the use of nickel coatings with a structured surface that has been specially designed for use in thin-slab casters.
Advantages of mold coating
Nickel coating with a structured surface offers several advantages for the casting process:
- Mitigation of peak heat transfer
A structured surface in the meniscus area helps to reduce the local thermal load. This reduces thermal stresses and minimizes the risk of thermal cracks in the copper surface. - Longer service life
The nickel coating forms a protective layer which prevents mechanical wear and the formation of brass on the surface of the mold. This extends the service life of the mold and reduces maintenance costs. - Preservation of the surface structure
Examinations have shown that the structured surface of the nickel coating does not show any signs of wear, even after prolonged casting campaigns. This results in consistent performance and reliable heat transfer.
Practical application and results
Plant tests at Tata Steel in IJmuiden have confirmed the effectiveness of the nickel coating. The mold plates were coated with a variable layer thickness, with the top section of the mold having a structured surface in order to reduce the thermal load. A thicker, smooth coating was applied in the lower area to minimize mechanical wear.
The measurements showed that the structured coating effectively reduces heat transfer in the meniscus area. This significantly reduces the thermal load and extends the service life of the mold. In addition, it was found that the mechanical damage on the coated surface is significantly lower than on uncoated copper plates.
Tailor-made coating solutions
SMS group is continuously advancing the further development of coating technologies and is transferring these innovations specifically to new applications, such as the thin-slab casting process. A wide range of processes, including thermal spraying, nickel plating and welding, are available in China, India, Brazil, the USA and Europe, always close to the customer and flexible for solving specific problems on site.
For our customers, this means measurable added value: Investments are used more effectively (CAPEX to OPEX), plant availability and output are increased, the quality of the final product is improved and the overall plant efficiency (OEE) is sustainably increased.
Conclusion
The introduction of nickel coatings with structured surfaces represents a significant advance in the technology of thin slab casting. These coatings provide an effective solution to reduce thermal and mechanical loads, thus extending the service life of the mold and reducing operating costs. By combining nickel coating and a defined surface structure, SMS group is thus able to offer a promising approach to extending the mold service life during thin slab casting under real production conditions.
Future research and optimization of coating materials and technologies will contribute to further improving the efficiency and sustainability of the casting process.