In the diverse world of steel, stainless steel and galvanized steel are both highly regarded star performers. With their unique properties, they have made their mark in a wide range of applications. But what happens when you put them together? Today, we’re going to find out whether stainless steel and galvanized steel can live together in harmony.
What is Stainless Steel
Stainless steel is known as the steel industry, “anti-corrosion master”. The reason why it can have such a powerful antirust ability, mainly because in the steelmaking time to add chromium, nickel and other alloying elements. These elements are like a layer of invisible protective clothing to the steel, can form a layer of very stable oxidized film on the surface of the steel. This layer of oxidized film can not only block the oxygen in the air, moisture and other corrosive substances in contact with steel, but also self-repair, once the slightest damage, will soon be able to regenerate, continue to protect the steel.
Because of this layer of “protective clothing”, stainless steel composite plate in many places can come in handy. In the industrial field, chemical equipment, food processing machinery and other corrosion resistance requirements are very high places, are inseparable from the stainless steel composite plate. It can maintain stability in a variety of complex chemical environments to ensure the normal operation of equipment.
What is Galvanized Steel
Galvanized steel’s “claim to fame” is a layer of zinc on the surface of ordinary steel. There are two main methods of galvanizing: hot-dip galvanizing and electro-galvanizing, of which hot-dip galvanizing is more widely used. Hot-dip galvanizing is the steel is immersed in molten zinc liquid, so that the zinc and the steel surface of a series of chemical reactions, the formation of a layer of tightly bound zinc layer. This layer of zinc layer can not only isolate the external corrosive substances, but also in the zinc layer is corroded, but also through its own sacrificial anode protection, priority is corrosion, thus protecting the steel substrate from erosion.
Galvanized steel in the construction industry is a “regular visitor”, such as building structures, roofs, fences, etc., everywhere it figures. Galvanized steel also plays an important role in outdoor facilities such as power towers and traffic guardrails. It can maintain good performance for a long time under the harsh environment of wind, sun and rain, providing reliable protection for people’s life and production.
Should You Mix Stainless Steel and Galvanized Steel
From a practical point of view, stainless steel and galvanized steel can not be mixed, really need to think carefully. Although both steels have good protective properties, their “temperaments” are not the same and using them together may cause problems.
Theoretically, mixing them is not completely unfeasible. In some specific environments and conditions, a reasonable combination of stainless steel and galvanized steel, to give play to their respective advantages, to meet the special needs of the project.
However, in practice, there are some factors that need to be emphasized. If it is not well considered, it is likely to bring some unexpected trouble. Therefore, before deciding whether or not to use a mixture of these two types of steel, it is important to consider a number of factors carefully.
Corrosion Risks When Mixing Stainless and Galvanized Steel
When stainless steel and galvanized steel come into contact with each other, a potentially big problem is corrosion. The “culprit” behind this is the bimetallic coupling effect. When two dissimilar metals are joined together in the presence of an electrolyte such as water or salt water, a miniature circuit is formed. In this circuit, zinc in galvanized steel because of its more active chemical nature, will act as anode, constantly losing electrons; and stainless steel is relatively stable, become cathode, receive electrons.
In this process, galvanized steel will accelerate corrosion. In some places with high humidity, such as seaside buildings, ships at sea, or industrial equipment often in contact with salt water, this corrosion phenomenon will be more obvious. If this is allowed to develop, the zinc layer of galvanized steel will soon corrode away, losing its protective effect on the steel, which in turn affects the stability and service life of the entire structure. Therefore, this corrosion risk should never be taken lightly.
How to Mitigate Corrosion Risks
In the face of the risk of corrosion when mixing stainless steel and galvanized steel, it is not hopeless, there are a number of effective countermeasures to choose from. There are a number of effective countermeasures that can be taken. A good idea is to put a ‘plastic jacket’ over the joints. You can use plastic film, plastic sleeve, etc. on the connection part of the package, so that in the two metals between the formation of a physical barrier to prevent them from direct contact, thus avoiding the occurrence of bimetallic coupling effect.
Coating metal surfaces with a thick layer of protective paint is also commonly used. Choose a paint with good durability and corrosion resistance, evenly applied to the contact surface of stainless steel and galvanized steel, can be isolated from air, moisture and electrolytes, reducing the possibility of corrosion. However, it is important to note that before applying paint, the metal surface must be cleaned to ensure that the paint adheres firmly.
Another method is to perform electrical isolation. Insulating materials such as insulating gaskets and insulating sleeves can be used to separate stainless steel and galvanized steel, preventing electrons from flowing between them and fundamentally eliminating the conditions for bimetallic coupling. This method is particularly suitable for applications with high electrical performance requirements.
Industry Applications and Examples
In the field of bridge construction, a mixture of stainless steel and galvanized steel is common, but special attention needs to be paid to corrosion. For example, in the construction of some cross-sea bridges, galvanized steel will be used in some of the structures to reduce costs, while stainless steel composite panels will be used in some critical parts to ensure long-term corrosion resistance. To avoid corrosion, engineers use painting, electrical isolation and other measures.
Both types of steel are also used in the automobile manufacturing industry. Some exterior parts of the car may use stainless steel composite plate to enhance the aesthetics and corrosion resistance, while parts such as the body frame will use galvanized steel to ensure strength and rust resistance. During the assembly process, the risk of corrosion due to contact between the two steels is minimized through proper design and protective measures.
Conclusion
Stainless steel and galvanized steel mixed use of this matter, like a double-edged sword. On the one hand, their respective performance advantages, if properly matched, can bring better results for the project; on the other hand, the corrosion risk of mixed use should not be ignored.
In practice, if you can fully understand their characteristics, according to the specific use of the environment and requirements, to take appropriate protective measures, or they can let them “peaceful coexistence”. But if these factors are ignored, it is likely to cause corrosion problems, affecting the safety and service life of the structure.
Therefore, in deciding whether to use a mixture of stainless steel and galvanized steel, we must be careful again and again, taking into account various factors, to make the most appropriate choice.
