Galvanisation is a process often used on ERW tubes. Its purpose is to aid steel in resisting corrosion, offering it protection and keeping it looking good. Stainless steel has these key traits too. As such, you are probably wondering which one is better for your next project. We are going to compare the two to help you answer this question.
How do you make galvanised steel?
Before making comparisons, we need to understand how you make galvanised steel. Basically, it is zinc-plated. There are a few ways to do it. As long as you perform them correctly though, they all offer similar results.
Hot-dipping is the most common steel galvanising method. Here, you dip standard steel in molten zinc. This creates a layer of zinc that bonds with the steel’s surface. It offers an appealing appearance and protective benefits.
Thermal diffusion and electro-dipping are other galvanisation methods. The first uses zinc powder, heating it in rotating drums so it vaporises and diffuses onto the steel’s surface. The latter uses electricity to bond zinc to the steel.
The zinc layer with galvanisation has the same purpose as the passive chromium oxide layer on the exterior of stainless steel. This aids the metal in resisting corrosion. Moreover, it repels dings, scuffs, and similar minor physical problems.
Now, we’ll move onto the comparisons. Afterwards, if you want to order ERW tubes, you can speak to us.
Corrosion resistance
Firstly is whether galvanised steel is as corrosion resistant as stainless. Generally, it’s not. Although, this will depend on the particular situations in which you intend to use your tubes. Galvanised products have a great resistance to chlorine and water. Yet, it pales in comparison to the performance of stainless steel in marine settings.
The protective layer present on galvanised steel isn’t self-healing like stainless steel’s passive layer either. So, over prolonged periods, parts tend to be less durable. Saying this, even if you damage the zinc layer, it will still be a sacrificial cell in the galvanic corrosion procedure. It will ensure rust formation on the zinc areas rather than the underlying steel.
Overall, stainless steel will provide better corrosion resistance and for longer. However, it is more costly. Choosing ERW tubes and galvanisation is generally the cheaper option.
The stronger material
As for which is stronger, when you compare at similar forms and thicknesses, stainless steel wins. An efficient way of comparing this is by examining each material’s tensile strength. This is the resistance a material has to breaking under tension. Stainless steel’s tensile strength normally begins at around 515 megapascals (MPa). It can go as high as 1300 MPa. Structural steel has a tensile strength of 400 MPa. Carbon steel has 841 MPa. Both are options for galvanisation. Adding zinc doesn’t influence the underlying metal’s tensile strength.
Heaviness
In most instances, galvanised and stainless steel will have very similar weights. The specific differences will change depending on the precise alloys. There is also the zinc coating thickness on the galvanised item. A thicker coating or more alloyed metals will result in higher weight.
Malleability
Galvanised steel provides the same malleability as the underlying steel. As such, in most scenarios, it will be more malleable than comparable stainless steel forms. However, you can choose austenitic grades. They have higher levels of nickel so it makes them more formable.
Heat conduction
Both galvanised and stainless steel should conduct heat in a relatively simple way. In the case of galvanisation though, you need to keep zinc’s melting temperature in mind. Even though molten zinc is non-toxic, heating beyond its melting point might create fire or burn hazards. This will happen as the zinc coating liquifies and separates from the underlying steel. On a structural level, both options should offer wonderful heat tolerances to use in high heat areas.
You’ll get the best ERW tubes from us
At Union Steel Tubes, we’re committed to providing every client with top tier steel tube. At the same time, we work hard to deliver all orders quickly or make them ready to collect. As a result, we can ensure a quick lead time for clients.
So, please speak to us if you ever need ERW tubes. We can offer galvanisation if you want to enhance the corrosion resistance and aesthetics.
