Continuous caster for long products

SMS Concast designs highly versatile billet casters, providing greater flexibility in production so that plant operators can react to changing market demands extremely quickly. Together with the development of secondary metallurgy, SMS Concast has sparked a revolution in its advancement of near-net-shape casting technology and paved the way for the further development of many plants in terms of the quality and quantity of their products.

Continuous casting for billets covers both small and medium round sections as well as same-sized rectangular and square sections, the typical size range of billets is 85–200 mm.

Bloom sections are required in cases where final steel products of the highest purity and flawless internal quality are to be produced for high-end applications. The same applies to particularly large end products.

In order to achieve the required purity and internal quality, SMS Concast continuous bloom casters have some striking features, such as the tundish heating systems, integrated molds (including INVEX^® mold technology), an electromagnetic stirrer system (CONSTIR), innovative strand support design, including dynamic mechanical soft reduction (DMSR), and controlled surface quenching. DMSR is necessity in order to achieve a sound bloom center and minimized center segregation. In addition to the mechanical components, SMS Concast also supplies the metallurgical models, such as the COOL solidification model.

Blooms can be as well cast on vertical casting machines and may very well replace ingot casting machines.

Beam blanks are near-net-shape products used to feed medium and heavy section mills. This state-of-the-art casting technology was invented by SMS Concast, which is the market leader in this specialist field.

Where beneficial, SMS Concast can equip the casters with special strand-reheating systems to control the beam-blank tip temperature before entry to the straightening zone. This is particularly important when micro-alloy steel grades are cast in large beam blanks, both to optimize the metallurgical properties and avoid transverse cracks. Also the SMS Concast ExpertShape mold tubes have a very positive impact to reduce web crack formation.

An important aspect is that SMS group can offer the complete processing chain for the production of beam blanks from one source: SMS Concast provides the caster, whereas the remaining parts of the process come from the global market leader SMS group, such as the EAF melt shop and secondary metallurgy upstream and downstream the required medium or heavy section rolling mill.

Vertical casting is an excellent alternative to a curved bloom caster of ingot casting for higher production, which ranges up to 1 million t/year. It also aims to achieve high product quality. Continuous vertical casting offers various advantages, such as avoiding any bending and straightening of the strand and creating excellent conditions for the better separation of non-metallic inclusions in the mold.

All curved continuous casters require the unbending of the curved strand in a straight horizontal direction. Depending on the section size, caster radius, casting speed, and steel grade, this unbending process leads to stresses and high levels of rates of strain within the just-solidified strand shell. In case of critical steel grades, this unbending and straightening process results in cracks either on the surface of the strand or at the solidification interface.

These problems can be overcome by pure vertical casting, since in the casting process any stresses and strains due to unbending is avoided, or by using a semi-continuous vertical caster to implement ingot casting.

The semi-continuous casting process is already a standard application for non-ferrous metals such as aluminum and copper. Still, the adaption to steel casting adds increased complexity due to its slower solidification rate.

The driving idea behind the VERSCON semi-continuous casting process developed by SMS group, is the requirement to cast one or two ladles on one or more strands into long blooms. The huge bloom length ensures a higher yield, whilst the semi-continuous casting process using a conventional mold and oscillation table guarantees a bloom surface comparable to that achieved by continuous casting. Once the strand has reached its final length, casting is stopped, and the strand is held in position until final solidification is achieved.

The VERSCON semi-continuous casting process combines the following advantages: utilization of small-scale production units (low CAPEX), improved yield compared to ingot casting, better surface quality than ingots, and an internal homogeneity and quality comparable to that of continuous casting.