Transforming Heavy Plate Production: Ultra-Thick Slab Casting

As the demand for heavy plates—especially those exceeding 120 millimeters in thickness—continues to rise, industries such as offshore wind, ­energy, and infrastructure are seeking products that ­offer strength and impeccable internal quality. ­Primetals Technologies has pioneered slab casters capable of producing slabs up to 460 millimeters thick. Combining these slab casters with hard reduction leads to advanced, high-quality heavy plate production.

The demand for high-quality heavy plate is on the rise among offshore windmills, new pipelines, and the energy sector overall. Moreover, meeting these demands is anything but straightforward. The application requirements for these sectors require stringent tests to assess the internal integrity of the produced heavy plates, meaning mechanical properties must be precise, reliable, and ideal.

From the liquid to the solid phase, casting heavy plate grades is a crucial step in achieving internal soundness, eliminating even minor imperfections. Steel producers are compelled to find effective ways to meet increased demands while maintaining high quality as these key sectors expand. Primetals Technologies has developed a bow-type continuous caster for ultra-thick slabs to support steel producers worldwide.

Conventional heavy plate production involves the production of ingots, i.e., pouring molten steel into a mold, followed by roughing and rolling. The solidification process during ingot casting is slow, along with slow directional heat transfer. This results in segregation zones and porosities, especially in the center of the ingot. Thus, an extensive reduction ratio of approximately five is applied to the ingot. This extensive reduction process helps eliminate defects and improve the overall integrity of the plate. However, ingot casting is more labor-intensive, time-consuming, and costly.

For modern steel producers, bow-type continuous casting is a clear fit for production capacity, efficiency, and overall yield. Until now, bow-type continuous casting has been limited in producing heavy plates. This is primarily because the maximum casting thickness of typical casters cannot exceed 400 millimeters. Due to soft-reduction techniques, the required rolling reduction ratios (2.5–3) are lower than in ingot casting. Still, they limit the final heavy plate thickness based on the as-cast thickness. Hard reduction applies five times more deformation in the caster than soft reduction, significantly decreasing porosity and improving the internal structure. This leads to greater achievable plate thicknesses because the rolling reduction ratio can be further reduced.

The application of hard reduction for ultra-thick slab casting is essential to achieving the highest-quality heavy plate. In this case, continuous casting requires segments that provide single roll motion while applying a high reduction force. Advanced automation solutions are needed to predict steel properties and the solidification point, as well as to adjust the casting gap. A secondary spray cooling system is designed to ensure uniform solidification. The application of dry casting also helps reduce reduction forces.

Hard reduction highly benefits from applying only one or two rolls with high roll forces for deformation. Thus, individual roll positioning as enabled by the Single Roll DynaGap segment is essential. In comparison, conventional Smart Segments, where the inner bow rolls are mounted on a single frame and can only move as a unit, would spread the deformation to at least five rolls. They are not able to maintain the target gap. Maintaining the ideal gap for hard reduction ensures the slabs emerge with the right properties for heavy plate production. (Pictured above.)

In addition to the mechanical features of the Single Roll DynaGap segment, integrated solutions from Primetals Technologies, including DynaPhase, Dynacs 3D, and DynaGap improve the functionalities of the segment.

DynaPhase determines the temperature-dependent material properties, such as liquid and solid temperatures, enthalpy, solid fraction, density, and conductivity. This is all used for thermal calculations based on the actual steel composition. Dynacs 3D secondary cooling provides real-time, three-dimensional temperature calculations for precise cooling control. It accurately assesses heat transfer from the slab surface via radiation, roll contact, convection, and spray cooling. This results in an exact determination of the strand surface temperature profile and solidification point. The system enhances heat transfer predictions to ensure accurate strand surface temperatures. This information is then directly fed into DynaGap.

DynaGap enables the remote control of roll gaps. Enabling rapid thickness changes and optimized slab quality, the system automatically adjusts the segment to achieve the optimum roll gap based on the thermal profile calculated by Dynacs 3D. It enforces thickness reduction in the final solidification zone, resulting in improved internal quality, especially for tube and plate grades, as well as minimizing centerline segregation and porosity.

Ultra-thick slab casting with SRD segments has proven its viability for heavy plate production. Recently commissioned casters equipped with SRD segments demonstrated the benefits of hard reduction. Slabs with high hard reduction showed a marked improvement in internal quality compared to low soft reduction. The dynamic application of hard reduction ensured precise deformation control, resulting in improved mechanical properties and a greater likelihood of passing ultrasonic tests.

By enabling the production of ultra-thick plates via continuous casting, steelmakers can now serve markets previously accessible only through ingot casting. This shift increases yield, reduces costs, and enhances energy efficiency and sustainability. Eliminating the need for feeder removal and ingot roughing saves time and resources, thereby reducing the carbon footprint of each ton of steel produced.

As the offshore and energy sectors continue to expand, the demand for ultra-thick, high-quality plates will only increase. The adoption of advanced casting technologies, like those pioneered by Primetals Technologies, will be essential to meet those demands. The integration of hard reduction, advanced automation, and innovative cooling solutions is setting a new standard for heavy plate production. With ultrathick slab bow-type continuous casting, producers can expect higher yields, improved quality, and greater efficiency. As global infrastructure demands grow, these innovations will play a pivotal role in supporting the growth and success of the offshore and energy sector while shaping a more sustainable future.