Steel is an alloy that is made up of iron. It also consists of carbon and manganese; sometimes it is coated with zinc as well. The processing of the steel is done according to the requirements which improves its usability. Iron is very likely to get rust and also offers very less tensile strength which makes it a weaker choice in different fields. This is where these two, galvanized and stainless steel was introduced.
Steel is one of the most important kinds of material that is being used in the manufacturing of so many things. It is steadily used in construction as well. It continuously gained popularity because it offers high tensile strength and is inexpensive.
Throughout the years, steel kept changing its composition according to the demands. Iron was processed into steel because it was lacking some of the abilities. There were so many changes in the processes of how steel is produced. Galvanized and stainless steels are two of them.
The choice between the two of them is completely dependent on the usage. We can use both of them in most cases but we have to consider one of them because of the processes involved in manufacturing as well as the difference in pricing.
What is Galvanized Steel?
“Galvanized Steel is the steel coated with a protective layer of zinc, offering rust prevention through the process of galvanization.”
Zinc is a very reactive metal. It is chosen over the other metals for the process of galvanization because it is more reactive than iron and other metals as well. When galvanized steel reacts with oxygen, zinc coated layer reacts and forms a zinc oxide layer which becomes a protection against corrosion. It forces oxygen to react with it rather than reacting with the steel, making it corrosion free.
How Steel is Galvanized?
Steel can be galvanized through different techniques. The selection of the technique depends on the scale of manufacturing, the presence of skilled labor, the availability of the machinery, etc. Some of them are explained below for a better understanding:
Hot Dipping: It is one of the most common ways of galvanizing steel. In this technique, steel is dipped in molten zinc. A protective layer is thus created on the steel which binds in such a way that it becomes a shield against rust. The steel is then cooled down which doesn’t require any further processing.
Thermal Spray: It is another famous technique of zinc coating on steel. In this process, melted zinc is sprayed on the surface of the steel which serves the purpose of protection. The thickness of the zinc coating (number of microns) depends on the standards being followed.
Electroplating: In electroplating, the surface of the steel is coated with zinc by providing a direct electric current. It is an ancient way of galvanizing steel but is still popular among a high percentage of manufacturers.
Sherardizing: It is commonly known as dry galvanizing. In this method, zinc is coated on the steel surface by getting contact with zinc dust. Water is not used in this technique which makes it unique from the other mentioned techniques.
How Well Does Galvanized Steel Resist Corrosion?
Galvanization on steel is done to resist corrosion. The zinc coating helps to prevent corrosion by reacting with oxygen. It is because zinc is more reactive than steel (iron). Zinc reacts with oxygen, preventing it to react with iron.
The problem with galvanized steel is that it doesn’t heal itself in case of any damage to the coating. For example, if we need to weld a few parts when using galvanized steel, we either have to galvanize it after the welding process or we need to re-galvanize it.
Galvanized steel is way cheaper than stainless steel. There is a standard rate of regular untreated steel. Galvanized steel is just above the price of regular untreated steel. So, it becomes the choice for regular steel users to choose for more protection against corrosion.
Applications of Galvanized Steel
Most of the applications of galvanized steel are related to the sheets because they work well in that area. Some of the examples are:
- Doors & Windows
- Traffic Signs
- Pipes for Electric Poles
- Accessories in Pools
What is Stainless Steel?
“Stainless steel is a corrosion-free steel which is also an alloy but with added chromium and sometimes nickel.”
Chromium is the key to stainless steel. It is added 15-20 percent and plays an important role in hardening the steel. Chromium oxide is formed when the steel is brought into the environment and reacted with oxygen which performs as a protective field against oxygen.
Nickel is also another metal that is important in making it stronger as well as providing more protection against corrosion.
Carbon, silicon, nitrogen, and manganese are also some important metals that are used in the preparation of stainless steel.
How Stainless Steel is Made?
Stainless steel is an alloy. It is made when all the metals melted together, such as iron, nickel; carbon, etc. are fused to make an alloy. The ratio of all metals depends on durability, malleability, pricing, shield against corrosion, etc.
There are six important steps involved in the preparation of stainless steel. Their steps are:
- Heat Treatment
There are some famous grades of stainless steel like 304, 316, 420, etc. which are standards and are recommended for different applications.
How Well Does Stainless Steel Resist Corrosion?
Stainless steel performs far better than regular or galvanized steel. It is because it consists of chromium which performs well by making a chromium oxide layer. It is also called a passive layer because it reforms itself in case of any damage is done to the surface of the steel. Hence, stainless steel works far better than galvanized steel if we talk about corrosion.
Stainless steel is expensive. It is around three to four times more expensive than regular untreated steel. The reason behind being expensive is the process involved in the manufacturing and the addition of other metals like chromium and nickel. Expensive doesn’t mean that it is overpriced, the cost of preparation increases with the processing phenomenon as well as the addition of other metals.
Applications of Stainless Steel
There are many applications of stainless steel. We especially used them in those areas where we cannot take any risks of corrosion. Some of them are listed below:
- Aircrafts Components
- Ships Components
- Different sorts of Fasteners
- Many areas of the Medical Field
Medical Use: Stainless steel is a complete win over galvanized steel because zinc coating can be problematic in many medical procedures. On the other hand, stainless steel can be customized (ratios of different metals in an alloy), according to particular needs which makes it the best option for use in the medical industry.
Major Properties of Galvanized & Stainless Steels
There are several properties of metals that we are going to discuss because both galvanized and stainless steel shows some difference in properties. We will learn one by one to understand the differences in different fields. These properties are discussed below:
Magnetic in nature: Almost every kind of steel is magnetic. Galvanized and stainless steel, both are magnetic in most cases. Galvanized steel is magnetic in almost every state as the zinc coating is very thin which doesn’t overcome the magnetic nature of the steel. Austenitic stainless steel is non-magnetic and is used in high-end applications.
Welding: Both galvanized steel and stainless steel can be welded properly. The issue is that the zinc coating on the galvanized steel gets damaged from welding which will not serve the purpose of corrosion-free steel. We have to keep that in mind so we can galvanize the steel after the welding is done.
Tensile Strength: Tensile strength is a measure that tells us about the strength of any metal. Galvanizing doesn’t make any changes in the tensile strength of the standard structural steel. However, the tensile strength of stainless steel is much higher. It means that stainless steel is much stronger than galvanized steel because of the materials in it.
Malleability: Galvanized steel is much more ductile than stainless steel which help makes complex components.
Tolerance of Heat: Galvanized and stainless steel both perform well in high temperatures. The problem with the excessive heating of galvanized steel is that it may get fired and the melting of zinc may become harmful to any person. Moreover, the damage to the layer will be problematic because it may start corrosion.
Chlorinated Water: Stainless steel performs well in the water but there is a twist in the story and that is except chlorinated water. Chlorine is a very strong oxidizer and it reacts with stainless steel easier than galvanized steel. That is the reason why we mentioned it in the applications of galvanized steel.
Steel is one of the major materials which is being used in almost every field. The mentioned types i.e. galvanized steel and stainless steel both possess some advantages over each other. The complete discussion above can help you to get a general idea of the selection among them. The key is the right selection for the right purpose.
Galvanized steel is cheaper and can replace standard structural steel in most of the areas where corrosion was overlooked in the past. Moreover, we can galvanize any regular steel much easier than converting it into stainless steel. This is one of the key points for it. Galvanized steel also performs well in chlorinated water which is also a very important point to be noted.
Stainless steel is expensive but there are many applications where we need to select it as they offer more benefits. The medical field is completely dependent on stainless steel. They are many different versions of stainless steel are available in the market. The selection purely depends on the task which needs to be fulfilled.
Finally, we will conclude the topic by telling you that both types of steel are readily available and are famous in the domain we are using for. Both of them are resistant to corrosion.