What is slab casting?
It is an intermediate and semi-finished steel product that is obtained from the ingot rolling process or the continuous casting process. The cross-section of the slabs is not square, but rectangular, and is used as a raw material for making flat-rolled products, including coils and hot-rolled sheets.
Most slabs are made of carbon steel, but stainless steel slabs are also found. This product consists of alloys such as iron, chromium, copper, manganese, nickel, silicon and molybdenum.
Slab applications
Casting slabs It is used to produce all kinds of flat steel products such as sheets, plates and coils, as well as in the heavy machinery industry. According to the declared standard dimensions, the thickness of this steel sheet is very low, so that it may cause problems when cutting and it is necessary to use devices with high facilities for cutting.
Important features of Takthal or Slab
Having a completely smooth surface without crust
Free from any external and surface as well as internal defects
without any cracks
without any shrinkage cavity on its surface
There should be no traces of boils on them.
There should be an anti-rust layer on them and it is better if this layer is stretched on both sides of the slabs.
without any shrinkage cavity on its surface
Among the surface defects in slabs or slabs, there can be longitudinal depressions and sometimes transverse depressions. Among its other disadvantages, we can refer to two skins, surface flaking, as well as corner bending or corrugation of its surface. Also, among other surface defects of Takthal, we can refer to metal drops, surface stains, surface scratches, gas or needle holes, and surface perforations.
Also, among the geometric defects in the slabs, we can mention the rhombus, bulges and depressions.
Advantages of beds
One of the great advantages of slabs is that they have many uses, and this has made it possible to export them and gain currency for the country if the necessary standards are met in their production and the quality is high. Slabs are used in the production of various iron parts. Perhaps its most important application can be considered in steel sheets. It is also used in the production of beams, pipes, rods and coils. These sheets are widely used in the machine building industry.
Types of slab production methods
Long furnace method, Kanwar Tor (traditional method)
The blast furnace method is a traditional method that uses indirect regeneration to produce slabs. Considering that Iran has high-quality coal resources, this method is a practical method. At first, iron ore with lime and coke is put into the blast furnace and raw iron (molten iron) is extracted. To remove the impurities of molten steel obtained from raw iron, raw steel is obtained by removing carbon and adding oxygen. Further in the unit Slab casting Continuously, the melt is poured into the mold, it is cooled by separating the product from the mold and spraying cold water, and turns into a frozen ingot. At the end, the desired length of the slab can be achieved with different cuts.
Electric furnaces
Using electric furnaces and remelting scrap iron and steel, in this method, iron baskets are poured inside the furnace. Due to the lack of scrap sources in the world and the increasing growth of its price over the past years, in this method sponge iron is also used for melting in the furnace along with scrap. Therefore, simultaneously with the melting of scrap iron, a combination of sponge iron and slag-forming materials such as coke, bentonite, lime and other additives are added to the melting from the upper part of the furnace, and after sampling, by adding oxygen, impurities, especially carbon, are oxidized in the melt. Finally, it is produced by homogenizing molten steel. in the unit Slab casting, molten steel is poured into a water-cooled copper mold and then turned into a frozen steel ingot by spraying with cool water.
Induction Furnace
The induction furnace method has a high cost due to the use of electricity, electrodes and additives, on the other hand, there are two problems in these furnaces that have caused them not to be used.
The first problem is that the induction furnace cannot control the oxygen well, and this causes defects in the product, because the oxidation of the ferroalloy occurs due to the dissolved oxygen hookah in the melt. The second problem of this method is dephosphorization and desulfurization of the induction furnace.
