In construction industries, there are different methods and processes in which stainless steel is welded with low alloy steels. Stainless steel and galvanized steel are also used together in the industry with many applications. For example, stainless steel pressure vessels galvanized fasteners, etc.
Sometimes stainless steel is galvanized when we are looking for a precise level of corrosion protection. The presence of two unlike metals in a system is not always a sign of a problem but it can become an inconvenience. Here we are going to answer the question “Can we weld stainless steel to galvanized steel?”. So if you are interested to seek more information about it, you are on the right page.
Stainless and galvanized steel
To be familiar with this concept, first, we need to understand the type or nature of stainless and galvanized steel and their mechanical properties.
Welding process and problems
Welding stainless steel to galvanized steel provides excellent corrosion protection. But during welding this type of corrosion protection system, you might encounter some problems.
Anodic nature of zinc layer
As we know that the galvanized steel is coated with a zinc layer. So when this zinc layer comes in contact with other metals, the risk of bi-metallic corrosion increases.
The formation of the bi-metallic couple will cause accelerated corrosion to the anodic metal. The extent of this corrosion depends on the relative size of the surface area of the two metals. And it also on the positions of the metals.Galvanized steel is anodic to most metals. So when it is connected with other metals, the zinc layer not only shields the base steel beneath it but also tries to protect the other connected metal.
In this case, stainless steel becomes a negatively charged cathode. And galvanized steel becomes a positively charged anode. This results in fast consumption of the zinc layer which can decrease the overall lifetime of the metal.
Some atmospheric conditions should also be taken under consideration while welding galvanized steel to stainless steel. There is a possibility of substantial corrosion under moderate humidity in the environment. However, electrically isolating the two metals would be best if the two surfaces are present in salt water air.
Removal of zinc layer
When welding stainless steel to galvanized steel, it is necessary to remove the zinc layer from the heated zone. Because there is a possibility of zinc getting into the weld. This can result in liquid embrittlement and reduced corrosion resistance after the finishing of the weld.
There is also a possibility that the fumes coming from the zinc coating can result in health and safety problems. The areas of stainless steel which are to be welded should also be clean properly. All the dust, oil, or grease should be removed. Otherwise, it might lead to intergranular corrosion.
Materials used for welding
The material used for welding stainless steel to galvanized steel such as filler material, settings, shielding gas, etc must be rightly selected. The melting points of both metals are clearly different from each other. That is the reason why choosing the right filler material is very important.
Welding machines can be used depending upon the material’s thickness and task frequency. You can use MIG, ARC, and TIG welding to do this task. Each process yields a different result and requires a certain skill and knowledge to accomplish.
So if we sum up the whole thing, to weld stainless steel to galvanized steel, we have to be careful about the corrosion which might result when two metals react with each other. That’s why it should be done accordingly under suitable environmental conditions to prolong the lifetime of metal.