Metal sections are manufactured using a variety of production methods. Even just the stainless steel non-rusting flat sections offered in the materials4me Webshop are available in three different variants. Here we show you which manufacturing methods exist and what the differences are.
Not every material can be produced using every method. For the sake of simplicity, we will limit ourselves to the material of stainless steel, also known as V2A.
The product is rolled at temperatures above the recrystallization temperature. This temperature is material-specific and is generally about 60% of the melting temperature of a given material. Hot rolling requires low shaping forces, and no hardening of the material takes place due to the continuously occurring recrystallization.
The dimensional accuracy is limited due to thermal deformation, thermal shrinkage and scaling. The dimensional tolerances are larger in comparison with other production methods and the surface of the product is rougher.
Hot rolling is an extremely efficient manufacturing method for bars since few production steps are required. This process is ideally suited for mass production and relatively inexpensive.
The stainless steel is cold-rolled at temperatures below the recrystallization temperature. However, the cold-forming capacity of a material is limited, and the required shaping forces are high.
The number of required production steps is significantly greater than for products produced at higher temperatures. For example, subsequent heat treatment at temperatures above 1000°C is absolutely necessary. The additional steps make the metal section significantly more expensive than the hot-rolled variant.
The achievable precision of the geometric dimensions of the product is significantly higher than with the hot-rolled method. Undesired dimensional tolerances are therefore smaller. Due to the additional rolling steps, the surface is smoother and therefore also glossier.
Cold drawing is a method of cold shaping by means of drawing that shapes primarily the areas near to the surface. In this process, a die is drawn over a round or flat bar. In the areas near the edges, the material experiences significant cold hardening. The primary goal is to improve the product with regard to its surface properties, dimensional tolerances, straightness and levelness.
Cold-hardened areas can tend toward uneven tension distributions in the areas near the surface of the material. This can result in distortions during subsequent processing. Due to the additional processing steps, drawn metal sections are more expensive than the hot-rolled variant.
The material has good dimensional tolerances, straightness and levelness. The drawing lends the metal a smooth, bare surface.
In the context of flat bars, cut means that the flat bar was separated from a sheet or strip at its desired width. For production reasons, this results in a sharp cut edge.
The sharp cut edges can be a disadvantage in some applications. A certain degree of cold hardening occurs in the edge area.
Cut flat steel is inexpensive. Thanks to cutting from a sheet or strip, diverse bar widths can be produced quickly.
Grinding is a mechanical process in which a small amount of material is removed from an area of the surface. The material removal is accomplished using a type of sandpaper belt with hard particles. Sandpaper of varying grits are available with different types, sizes and distribution of embedded particles. The most common grit levels are 180, 240 and 320. Grinding after production is intended primarily to improve the appearance of the product.
The surface of the products is more sensitive to soiling and possibly corrosion. The visual appearance of the surfaces can vary between production batches.
The surface has a specifically adjustable and homogeneous appearance. Grinding permits a large variety of surface properties.
Brushing is a process similar to grinding. This also involves removal of a small amount of material from the surface. In contrast to grinding, a fabric belt of nylon with embedded abrasive particles is used for brushing.
Due to the similarity with grinding, the brushed material has the same disadvantages. The surface is more sensitive to soiling and possibly corrosion. The visual appearance of the surfaces upon delivery can vary between different batches.
The material has a visually homogeneous surface appearance. Brushing typically results in a more finely textured product surface than classic grinding. The roughness values are lower.
Seamless circular tubes
Seamless steel tubes are produced by punching holes in solid material followed by additional processing steps. Seamless tubes offer the security of a fully uniform structure and are therefore also suitable for high-pressure applications. The largest outer diameter is 711 mm. Wall thicknesses of up to 125 mm can be produced.
Due to the production process, seamless stainless steel tubes are more expensive than welded tube sections. The manufacturing tolerances for seamless stainless steel tubes are greater than for welded tubes. As a result of the production process described above, seamless stainless steel tubes have a rougher surface than welded stainless steel tubes.
Thanks to the uniform structure, the products are suitable for high-pressure applications. No seam can be seen either on the outside or the inside. Another advantage of seamless stainless steel tubes is that they can offer superior corrosion resistance because there is little potential for contamination.
In contrast to welded tubes, seamless tubes have no disadvantages in terms of shapability. Seamless stainless steel tubes are therefore often suited for critical applications, such as 3D bending.
Welded circular tubes
Welded tubes can be manufactured in large quantities and offer the advantage of being high-quality while remaining inexpensive. Longitudinally welded steel tubes are produced from steel strips, wide bands or steel sheets, among others. Here, the material is shaped into a tube by bending, and the band edges are then welded in the lengthwise direction into a closed steel tube. Outer tube diameters of up to 2500 mm with wall thicknesses up to 40 mm can be produced.
Welded stainless steel tubes do not have the same metallurgical properties in the weld seam zone as in the rest of the tube material. Most welded tubes require heat treatment after production. Due to the weld seam factor, welded tubes suffer a disadvantage in the applicable calculations for internal tube pressure or for structural applications.
As a result of the simpler production method, welded stainless steel tubes are less expensive to manufacture. Welded stainless steel tubes have better wall thickness tolerances. For this reason, they also feature somewhat better concentricity. Ground or drawn tube profiles exhibit no externally apparent difference from seamless tubes. Hollow sections are also suitable for telescoping after additional scraping of the inner seam.
Buy non-rusting stainless steel sections online from materials4me
At the materials4me Webshop from thyssenkrupp, you can purchase stainless steel non-rusting sections online. Fast, easy and with no minimum order quantity. If you have any questions about our selection, please use our contact form. We will be happy to assist you.