What's the difference between carbon steel profiles and stainless steel profiles?

Electro galvanized steels (EN 10152:2017 - EN 10268:2006), cold-coated via a static electrolysis process, are generally used in lower gauge applications and/or in favorable climatic conditions for a more refined aesthetic appearance for subsequent protective surface treatments, such as painting or enameling.  This is why they're often used in the automotive industry and in the manufacturing of household appliances and interior furnishings.

Hot-dipped galvanized steels (EN 10346:2015 - EN 10346:2015), formed via a process called "galvanization" (also referred to as hot dipping), provide greater corrosive resistance, thanks to their increased thickness and the various types of coatings that can be used. 

The galvanization process is characterized by the continuous entrainment of the strip in a bath of molten zinc. The entrainment speed determines the thickness of the zinc layer that's formed. 

Some examples of coatings: 

• Sendzimir Galvanized (Zn >99%)                                                                   
• Galfan Zinc-Aluminum Alloy (Zn 95%-Al 5%)                                               
• Aluzinc Aluminum-Zinc-Silicon Alloy (Al 55%-Zn 43.4%- Si 1.6%)              
• Aluminized Aluminum-Silicon Alloy (Al 90%-Si10%)                                             
• Zinc-Magnesium Alloy (Mg+Al 1.5-8% - Mg>0.2%).

Stainless steel (UNI EN 10029:2011) is characterized by the almost total absence of Carbon (C <0.07%) Chromium content (Cr > 10.5%). The latter promotes a natural passivation layer, giving this type of steel a high resistance to atmospheric corrosion (higher than galvanized steel) as well as greater resistance to heat and corrosion caused by the use of acids or corrosive products. Due to its shiny appearance and the chemical and physical, molecularly compact composition, it's widely used in the agro-food and pharmaceutical industries. 

Unlike coated steels, stainless steel, although more expensive due to high production costs, guarantees an almost endless service life, is more hygienic and cleaner and does not experience wear and tear over time even if scratched or etched, thanks to the action of chromium reacting chemically within. The durability of coated steels, on the other hand, depends on both atmospheric conditions and mechanical wear and tear.  

The main differences between galvanized steel profiles and stainless steel profiles can basically be identified through two elements:

• cost: Stainless steel is significantly more expensive because the manufacturing process is more complex. Galvanized steel, on the other hand, is more economical because galvanizing is a quick and easy process.
• durability: stainless steel holds up longer over time because, if scratched, it continues to be protected due to the zinc within. Conversely, galvanized steel will only be protected as long as zinc is present on the surface.

The differences between these two materials obviously also depend on the type of use and various situations. To give an example, let's consider solar panels. They're not likely to be scratched, but are subjected to atmospheric forces. In this case, galvanized steel is preferred, as it is more economical.

To understand how long the galvanizing will last on these installations, you can refer to technical data regarding annual zinc loss based on the environment in which the product will be exposed. This will allow you to determine the type of galvanization required. 

Considering a normal environment (non-maritime, urban outdoor or low-salinity maritime) with a loss of about 1 micron per year, we would identify a Z275 coating as the optimal solution.

To receive more information regarding carbon steel profiles, stainless steel profiles or other types of profiles and services offered by Profilsystem, feel free to contact us!