How to Select A Steel Billet Continuous Casting Machine?

When designing a steelmaking plant, the first priority is the selection of the steel billet continuous casting machine (CCM). A suitable CCM should be determined according to the product plan, product quality, and reduction of construction investment. Proper selection of CCM will create conditions for future management and high efficiency and high quality production of continuous casting machine.

Types of Steel Billet Continuous Casting Machine

There are many kinds of continuous casting machines, such as vertical continuous casting machine, arc continuous casting machine and so on. They all have their own advantages and disadvantages.

Vertical Steel Billet Continuous Casting Machine

The main parts of the vertical continuous casting machine from the tundish to the cutting station are arranged in a vertical line. The entire fuselage stands on the ground level of the workshop or is arranged in a deep pit underground.

Advantage

• This continuous casting machine occupies a small area and is compact in equipment;

• There is no bending deformation of the high-temperature billet, and there are few cracks on the surface and inside of the billet;

• The inclusions in the unsolidified liquid in the slab are easy to float up, and the molten steel is relatively "clean";

• The structure of secondary cooling device and nip roller is simple and easy to maintain.

Shortcoming

• The height of the casting machine is too high, it is necessary to increase the height of the plant or dig a deep pit, and the infrastructure cost is expensive;
• It can only cast at low speed, low productivity;
• The high hydrostatic pressure of the molten steel can easily cause the shell of the solidified slab to bulge, resulting in poor quality of the slab.

Arc Continuous Casting Machine

The curved continuous casting machine uses a curved crystallizer with a certain radius of curvature. Its crystallizer, secondary cooling device and tension straightening device are all arranged on a quarter arc of a circle with a certain radius. The slab is bent when it is solidified in the mold, and the slab with the liquid core is pulled out from the mold, runs along the arc track, continues to spray water for cooling, completes solidification at a quarter of the arc, and then straightens and pull out.

Advantage

• The height of the curved continuous casting machine is only one-third of the vertical type;
• The construction cost is low;
• The hydrostatic pressure of the steel is small;
• The quality of the billet is good;
• It is easier to lengthen the fuselage, so it can be cast at high speed and has high productivity.

Shortcoming

• Due to the bending and straightening of the billet, it is easy to cause internal cracks;
• The distribution of inclusions in the slab is uneven, and there is agglomeration of inclusions on the inner arc side;
• The equipment is complex and difficult to maintain;
• Although the arc continuous casting machine has disadvantages, due to the technological progress in equipment and technology, it is still the most widely used model in steel mills all over the world.

Selection Principle

1. The production capacity of the continuous casting machine should match the production capacity of the steel melting furnace. In order to develop the production potential of steelmaking, the production capacity of the continuous casting machine should be 10-20% rich.

2. Meet the requirements of steel grade and rolling section specification. According to the statistical data of production practice, the current application of vertical, vertical bending and arc continuous casting machines can meet the requirements of pouring ordinary carbon steel, low alloy steel, alloy steel and different specifications of sections, but the arc continuous casting machine It is the most widely used (accounting for more than 60% of construction continuous casting machines).

3. Meet product quality requirements. The quality of the slab mainly includes two aspects, one is the internal cracks and segregation of the slab, and the other is the purity of the slab. Taking the above two factors into consideration, the arc continuous casting machine is still an ideal model. If auxiliary measures such as refining outside the furnace and non-oxidizing pouring are adopted, the curved continuous casting machine can fully meet the requirements of product purity. In order to completely solve the shortcoming of inclusion accumulation in the inner arc of the arc continuous casting machine, there is a new development trend to build a vertical curved continuous casting machine with a straight mold and a vertical section (2-3m).

4. Reduce construction investment and equipment manufacturing costs.

At last

Regarding the choice of models, there is no uniform standard. Combined with the factory's product plan, comprehensive consideration should be given to productivity, product quality, casting machine height, and investment. The construction of steel billet continuous casting machines should be regarded as a systematic project. In the upstream of the continuous casting machine, it should be considered that steelmaking should have a guarantee system for continuous casting to provide qualified molten steel (such as refining outside the furnace), and in the downstream of the continuous casting machine, the possibility of hot delivery, hot charging and direct rolling of the casting billet should be considered and rolling product quality assurance system.