Striking while it’s hot using High-Pressure Air.
Steel comes in many grades, specifications, shapes, and finishes. There are over 3,500 different grades of steel, each with unique properties. Different types of steel are used for various applications, such as infrastructure, appliances, vehicles, wind turbines, and many more.
However, optimizing steel's properties for each application goes beyond changing the chemical composition. The manufacturing processing of steel can also significantly impact steel products even when the grades and specifications are the same. One key distinction among prefabricated steel products is the difference between hot rolled and cold rolled steel.
Hot rolled steel is roll-pressed at very high temperatures. Over 1,700˚F, above the recrystallization temperature for most steels, makes the steel easier to form, resulting in more accessible work products.
To process hot rolled steel, manufacturers first start with a considerable, rectangular length of metal, called a billet. The billet is heated and then pre-processed and flattened into a large roll. It is kept at a high temperature and run through a series of rollers to achieve its finished dimensions. The white-hot strands of steel are then pushed through the rollers at high speeds. Rolled steel is spun into coils and left to cool for sheet metal. Materials are sectioned and packaged for other forms, such as bars or plates.
What are the benefits of hot rolled steel?
Hot rolled steel typically requires much less processing than cold rolled steel, making it cheaper. Hot rolled steel is allowed to cool at room temperature, and it's essentially normalized—meaning it's free from internal stresses that can arise from quenching or work-hardening processes.
However, the hot rolling of steel leaves a scale layer on the surface. The scale forms as the steel react with the atmosphere on cooling from its high temperature. Scale on the surface can cause significant problems for subsequent use and coating of the steel.
Further, cooling of steel is done via annealing. Oxygen reacts with iron on the hot metal surface. Iron oxides, the so-called scale, arise, which are then removed. If the scale remains on the metal surface, it rolls into the steel in the subsequent rolling process, which has a negative influence on the steel quality. Specific parameters cannot be achieved, such as a predetermined strength with the finished product. The cost a steelwork can achieve for its products on the international market is in line with the steel's quality and purity, so scale removal is imperative.
Hydromechanical descaling through high-pressure water offers the possibility of adjusting the pressure matched to the respective material to guarantee optimal descaling.
Generally, there is a trend towards descaling with higher pressures up to 400 bar. This increased pressure allows a simultaneous reduction in the quantity of water used. Reduction in the amount of water used reduces the cooling effect on the steel and reduces the energy used to supply and filter the water.
In hydro mechanical descaling processes, the jets are formed by special descaling nozzles arranged on spray headers in a mill descale through which the product (slab, strip, billet, bloom, beam blanket, etc.) travels—working pressure range from 80 to 450 bar.
High pressure is generated by using High-Pressure Plunger Pumps or a combination of High-Pressure Air generated by compressors and water. The latter is much more power-efficient and requires less maintenance; however, the overall footfall of the solution increases as there are a lot of accessories needed.
Elgi Sauer Compressors
Elgi Sauer Compressors are used in a wide variety of metallurgical applications, encompassing the entire range of processes for producing and using metals, metalloids, and nonmetals. Even under extreme environmental conditions, their particularly long operating lives make them more or less indispensable within the field of metallurgy.
Our customers benefit from the following advantages:
- Robust designs to withstand even the most extreme conditions (55°C ambient temperature)
- Compressors designed for permanent operation 24 /7
- The latest compressors, control systems, compressed-air treatment systems, and accessories
- Optimum customer services extend over the entire life of the product
- Long operating life with guaranteed availability of replacement parts (minimum 25 years)
- Turn-key solutions produced per customers' specifications
Minimal downtimes ensure high product availability.