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Carbon Steel vs Stainless Steel: What is the Difference Between Them?

March 25, 2023154 ViewskniveSource

Steel, a term that actually describes an entire family of metal alloys, is a versatile and common type of metal with a wide variety of applications and uses. There are many grades but most types of steel fall into two broad categories, carbon steels and stainless steels. Though they have the same basic composition of iron and carbon, steel types tend to have a variety of alloying elements. Carbon steel tends to have under 10.5% chromium content, but steel must be at least 10.5% chromium to be considered stainless. These differences give each type of steel its respective properties.

Stainless Steel

Stainless steel refers to a type of steel which is defined by the addition of chromium, and some other alloying elements such as nickel. It is sometimes called inox steel as it is designed to protect against oxidisation and so is ‘inoxidable.’ When exposed to oxygen, iron oxidises, making it rust, however chromium can be exposed to oxygen without undergoing this process. Stainless steel is therefore given a protective layer of chromium to create a barrier between environmental oxygen and the metal’s iron content. This allows it to resist corrosion or rust and makes it ‘stainless.’

Types of Stainless Steel

Different chromium levels of stainless steel will give it different properties, with a lower chromium content generally producing a cheaper but less durable steel. There are various types of stainless steel, which include:

Advantages

Disadvantages

Applications

Stainless steel has a wide range of uses and industrial applications, depending on the type of steel used. Stainless steel was first used in the automotive industry by Ford in the 1930s by Ford, and has since been used in cars for exhaust systems, grills, trims, and structural components. This extends to aircraft construction, where it is used in aeroplane frames, jet engines, and landing gear. Its resistance to corrosion, low maintenance, and how easy it is to clean makes it useful for transporting and interacting with chemicals, and it is often used in clean and sterile environments. Therefore, medical technology is also a fairly common use.

The strength, resistance, and flexibility of certain stainless steels make it a common feature in architecture, a property helped by its aesthetic features and attractive finish as well. For example, stainless steel is frequently used in the Eurostar Terminal in London and the Helix Bridge in Singapore.

One of the most common everyday uses of stainless steel is in food and the catering industry, where it is used to manufacture cookware, cutlery, kitchen accessories, and appliances. Utensils like knives are made from the less ductile grades of stainless steel, whilst the more ductile grades are used for grills, ovens, saucepans, and sinks.

Carbon Steel

Carbon steel, on the other hand, has far lower chromium levels, and is instead a carbon-iron alloy with only a few other materials, if any, as part of its makeup. As a result, it can be referred to as ‘low-alloy’ steel. Both stainless steel and carbon steel feature this basic composition, but carbon steel can be defined by its carbon content. This is normally around 2-2.5%, however this often varies. Though susceptible to rust unlike stainless steel, carbon steel is often cheaper and has its own varying mechanical properties based on carbon content.

Low-carbon steels are weaker and softer, but can be machined and welded easily; while high-carbon steel is stronger, but significantly harder to process.

Types of Carbon Steel

The defining element of any carbon steel alloy is its carbon content, and so this is how the various types of carbon steel are ordered and categorised.

Advantages

Disadvantages

Applications

The various types of carbon steel are applicable to a wide range of industries and sectors. Low-carbon steels can be used in automobile body components, pipes, construction and bridge components, and food cans. Medium-carbon steel is useful for railway tracks, train wheels, crankshafts, and gears and machinery parts requiring its higher strength and toughness, and similarly high-carbon steel is used in cutting tools, springs high strength wire and dies for its hardness.

Can Stainless Steel Weld to Carbon Steel?

Though it is technically possible to weld these different types of metals together, the popular consensus is that to do so is not advisable. The welding of carbon and stainless steel is not typically performed as they have differing levels of electrical conductivity. Carbon steel is normally preheated during resistance welding because it is more electrically conductive and doesn’t heat up as quickly as stainless steel. Therefore, reaching the right weld temperature is often extremely difficult. Therefore, it is generally advised that steels of similar types be welded together rather than mixing and matching.