What do the Chrysler Building, your refrigerator, and an offshore oil rig have in common? They’re all made from stainless steel.
In fact, steel plays such an integral role in our lives that it’s difficult to go a day without using something made from it or marked using it.
While your frying pan and the exhaust pipe on your vehicle are both made from stainless steel, they’re not the same type of metal. There are actually more than 100 stainless steel grades and classes.
Luckily, they can be broken down into three basic stainless steel types. Read on to learn about the properties and uses of each one.
What Separates the Different Stainless Steel Types?
Steel is an alloy, which is a type of metal that’s made when two metals (or one metal and one non-metal) are combined. All types of steel are a combination of iron and carbon. Unfortunately, steel is prone to corrosion.
Stainless steel is a special type of steel that’s resistant to corrosion thanks to the addition of chromium.
There are also different types of stainless steel. Each type is a combination of steel and chromium, but they have different proportions of chromium and may add other metals. Each type has a different purpose, which is why they have different chemical makeups.
Austenitic stainless steel is the most common type. It’s non-magnetic and is used in everything from cookware and medical equipment to architecture and pipes.
This type has the highest resistance to corrosion and rusting. That’s because it has a very high percentage of chromium and nickel. Chromium makes it corrosion-resistant, while the nickel makes it more flexible.
Austenitic stainless steel can be strengthened through cold work, but not through heat treatment.
Martensitic is the strongest type of stainless steel, but it’s the least resistant to corrosion. It’s a steel alloy whose only addition is chromium—it typically has no nickel or other added metals.
This type of stainless steel is magnetic, but it cracks easily. Because it can crack, it needs to be preheated and then heat treated for strength and protection. Martensitic is the only stainless steel type that can handle heat treating.
It’s used in knife blades, surgical instruments, turbines, and screw machines.
Ferritic stainless steel is less common than Austenitic because it’s not as resistant to corrosion. It’s also not as strong at high temperatures.
It’s magnetic and usually more affordable than other types of stainless steel, but it can’t be heat treated. It’s used in furnaces, boiler systems, and washing machines.
Ferritic stainless steel has a fair amount of chromium, but very little nickel. It typically also has small amounts of other metals like titanium or aluminum.
In terms of strengths and weaknesses, Ferritic stainless steel falls in between Austenitic and Martensitic. It isn’t as corrosion-resistant as Austenitic, but it’s less likely to crack than Martensitic
Each type of stainless steel has a unique purpose. While some stainless materials are magnetic, all types are corrosion-resistant. You can’t go wrong with stainless steel when you need a durable and versatile material.