How are two metals so similar yet so different? In the following article, we’ll take a closer look at steel and stainless steel and what the differences are between the two!
Steel and stainless steel are everywhere you look and even share a similar name, but how are steel and stainless steel different from one another, and are the two interchangeable? At first glance, you would assume they would be, but you would be wrong. In some situations, you could use steel instead of stainless steel and vice-versa, but each of these two metals has its own specific purposes and roles.
One of the easiest ways to imagine the two metals is to think of steel as stainless steel’s unrefined cousin, like the difference between a fine wine that costs hundreds of dollars and an alcoholic drink made of grapes. They may be both wines, but ones definitely much more high-quality than the other. Sure, if you drink too much, the result is the same, but the journey is much different.
In the following article, we’ll take a closer look at how steel and stainless steel are alike and different, different types of stainless steel, and why you might choose one over the other.
How Are Steel and Stainless Steel Alike and Different?
Uses of the metals
Both stainless steel and steel are two of the most common building materials in the world. Take a look around your home, and you’ll easily be able to identify several different types of stainless steel in regular household items such as sinks, cookware, and utensils. Steel is there too, but usually in less notable places like furniture, walls, ducts, foundations, and exercise equipment.
The physical differences between steel and stainless steel start with the strength, hardness, cost, and visual appearance. Stainless steel was initially widely used in commercial kitchens because of its resistance to chemicals, spills, and ease of cleaning. However, many people now use stainless steel in their home kitchens because of its physical appearance.
Resistance to Corrosion
One of the main ways the materials are very different is in the way they react to the environment. Steel will rust (turn into iron oxide) very easily. All that is required for this to happen is the presence of water and air! This is why steel is often painted or treated (such as being galvanized) to prevent water reaching the underlying steel. Rust is very unsightly, and therefore the use of steel for decorative purposes is very limited.
In contrast Stainless Steel has a naturally forming “passivation layer” that protects the metal from corrosion. The layer is very tough and invisible, making stainless steel very attractive looking. Stainless steel is therefore ideal in applications where the metal is exposed to air, water and corrosion causing substances such as acids. This is the situation in food preparation areas, and stainless steel is perfect as it resists corrosion and is easy to clean.
Mild steel pieces are very easy to join together with welding in order to manufacture finished items. However, stainless steel can be quite difficult to weld. Not only does the weld turn black with welding oxidation and look unsightly, but the protection afforded by the passivation layer is destroyed by the heat generated in the welding process. In the past abrasives and strong acids were the only means of removing the damaged surface. Today electrolytic weld cleaning machines such as the TIG Brush are able to quickly remove the black oxide and reform the passivation layer. This makes welding stainless steels safe, easy, and, best of all, very effective.
What is the manufacturing process which differentiates steel and stainless steel?
Steel is produced by adding iron to carbon. Carbon strengthens the iron. Steel is sometimes known as plain-carbon steel or mild steel, depending on where you live. Steel has a high amount of carbon and a low melting point (2600 – 2800F) which makes it relatively easy to smelt.
Stainless steel starts off similar to steel, but nitrogen, nickel, chromium, and molybdenum are added to it during the manufacturing process in different proportions, to provide the properties required for the application. It is the chromium element that forms the passivation layer.
How Many Types of Stainless Steel Are There?
One of the most commonly asked questions is ‘what are the different types of stainless steel and how are they different from one another?’ It’s a great question, and in the following section, we’ll take a closer look at the different types of stainless steel and what some of their applications are. It’s quite interesting to know how many different types of stainless steel we regularly use without ever knowing it.
It’s easy to look at stainless steel and say, ‘yes, that’s stainless steel,’ but did you know that different types of stainless steel have different purposes? In this section, we’ll look at the five main categories of stainless steel and what some of their uses are.
- Ferritic – You most likely have ferritic stainless steel in your home or business right now and didn’t even know it! Ferritic stainless steels contain high amounts of chromium with extremely low amounts of carbon. Their most common uses include automotive applications, industrial equipment, and kitchenware.
- Austenitic – Austenitic stainless steels are commonly used in the food, chemical, pharmaceutical, and petrochemical industries because of their high corrosion resistance, cleanability, and long life. While the cost of austenitic stainless steel is much higher, the extended life of the product usually makes it the most economical choice. Austenitic is made through the addition of nickel, nitrogen, and manganese and is also more prone to stress-related cracking.
- Martensitic – Some of the different things that use martensitic stainless steel include surgical equipment, cutlery, cooking utensils, dental instruments, tools, industrial blades, and springs. Both ferritic and martensitic stainless steels are remarkably similar, with both metals containing high chromium levels, but martensitic stainless steel contains a higher amount of carbon. It’s the high carbon level that allows martensitic to be tempered and hardened.
- Duplex – Duplex stainless steel gets its name from the two different metals that are combined to make it, ferritic and austenitic stainless steel. The two different types of duplex stainless steel are lean duplex and super duplex, with super duplex being resistant to almost all forms of corrosion, making it ideal for use in pipes throughout the world. Duplex stainless steel has good weldability and is used predominantly in chemical, gas, oil, and pollution applications.
- Precipitation Hardening (PH) – Copper, aluminum, and niobium is added to create precipitation hardening stainless steel. After it has been heat-treated, precipitation hardening stainless steel develops an extremely high strength-to-weight ratio, which makes it perfect for high-end applications such as the petrochemical and aerospace industries and for components such as springs and retaining rings.
How Are Steel and Stainless Steel Alike and Different – Conclusion
There you have it, why steel and stainless steel are alike and different. These two metals start in a remarkably similar fashion, but during the manufacturing process, each one takes a very drastic turn. The different types of stainless steel all have an especially important role in the world we live in, and we owe a lot to this very strategic metal.
If you have welded stainless steel components and you’re looking for an easy and safe way to clean discoloration or the oxidization from welded joints and seams, the TIG Brush is just what you’ve been searching for. The TIG Brush takes the hard work out of cleaning stainless steel welds and passivating the metal surface. Don’t hesitate to contact us today to find out how the TIG Brush stainless steel Weld Cleaning system could help your business.