Carbon Steel vs Stainless Steel

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Steel is a popular material used in construction, manufacturing, and everyday tools. Two common types are carbon steel and stainless steel, each with unique qualities. While both are made from iron and carbon, their differences in composition affect their strength, durability, and resistance to rust. In this blog, we’ll explain these differences in simple terms and help you decide which type of steel is right for your needs. Let’s get started!

What is Carbon Steel?

Carbon steel is a common type of steel made by mixing iron and carbon. It has more carbon, a lower melting point, and lasts longer compared to stainless steel.

Carbon steel has a high amount of carbon, usually up to 2.1% of its total weight. The American Iron and Steel Institute (ASISI) says the following things about carbon steel:

• There is no minimum amount of chromium, cobalt, nickel, titanium, tungsten, vanadium, or other metals that resist corrosion that must be used.
• Copper content must be at least 0.40% but no more than that.
• Manganese can't be more than 1.65% of the total amount.
• Copper cannot have more than 0.6% of it.
• The most silicon that can be in a product is 0.6%.

So, what are the benefits of carbon steel?

When there is a lot of carbon in steel, it changes how it works. In particular, it gets stronger and tougher. This is why high-carbon steel is used to make a lot of swords, knives, and other weapons with blades. In feudal Japan, swordsmiths were the first to use tamahagane, which is a type of high-carbon steel, to make weapons like the katana.

Does carbon steel rust?

Yes, carbon steel does rust because it doesn't have the same properties as stainless steel that keep it from rusting. Carbon steel is stronger and lasts longer than stainless steel, but it can rust and corrode if it gets wet. Carbon steel can rust if it gets wet, even if it's just a little bit. This includes moisture vapor in the air. Carbon steel is also harder to bend than stainless steel.

Carbon Steel Composition

Carbon steel is composed of iron and between 0.12% and 2.00% carbon. In the broader definition, alloy steels are also included, which can have up to 10.5% alloy content. Even within a range of less than 2% carbon, there are huge differences in physical properties, especially hardness.

Types of Carbon Steel

Low-carbon steel: This is the most common type. It has less than 0.25 percent carbon. This type of carbon steel is weaker and softer than most, but it is more flexible and easy to weld, so it is used for machining and welding at a low cost.

Medium-carbon steel: This type usually has between 0.25 and 0.6% carbon and between 0.6 and 1.65% manganese. It can be made better by heating it. But this can only be done on very thin pieces of metal if no alloying elements are added. It is stronger than low-carbon steel, but it is not as easy to bend.

High-carbon steel: This is the type of carbon steel that is the hardest and toughest. It is the least flexible and wears down the least slowly. The amount of carbon in it ranges from 0.6% to 1.25 %, and the amount of manganese is between 0.3% and 0.9%.

What is Stainless Steel?

Stainless steel is an iron alloy that doesn't rust or break down easily. It has at least 11% chromium and may also have carbon, other nonmetals, and metals to get other properties. The chromium in stainless steel makes it resistant to corrosion. The chromium forms a passive film that can protect the material and heal itself when oxygen is present.

Stainless steel, which is also called inox steel (from the French word inoxydable, which means "not oxidized"), lives up to its name by being very resistant to corrosion stains. When iron-based metals like steel are exposed to oxygen, they usually go through a chemical change called "oxidation" that changes how they behave. The iron oxidizes, which turns the hard iron into a metal with a reddish-brown color (iron oxide). At some point, the iron oxide will become so oxidized that it will break up completely.

Stainless steel is made to keep things from rusting. It has at least 10.5% of its weight in chromium. This is important because, unlike iron, chromium doesn't easily rust. Chromium doesn't rust or corrode when it's exposed to oxygen, which makes it an important part of making stainless steel. Stainless steel has a layer of chromium that protects it from corrosion. This layer acts as a barrier between the oxygen in the air and the iron in the metal.

Composition of Stainless Steel

Carbon and iron are mixed together to make steel. Stainless steels have at least 10.5% chromium, less than 1.2% carbon, and other elements that make them stronger. Other elements, like nickel, molybdenum, titanium, niobium, manganese, etc., can be added to stainless steel to improve its resistance to corrosion and its mechanical properties.

Types of Stainless Steel

The following are the types of stainless steel with different properties:

Austenitic: This is the most common type of stainless steel. It has a low yield strength but is resistant to heat and corrosion. It is often used to make home goods, pipes and vessels for industry, buildings, and facades.

• Austenitic: This is the most common type of stainless steel. It has a low yield strength but is resistant to heat and corrosion. It is often used to make home goods, pipes and vessels for industry, buildings, and facades.
• Ferritic: This type of stainless steel doesn't usually have nickel in it. But this type promises better resistance to corrosion, heat, and cracks than most other types. This type of stainless steel is often used in washing machines, boilers, and the construction of buildings inside.
• Martensitic: This type of stainless steel is usually magnetic and doesn't resist corrosion as well as other types of stainless steel because it doesn't have as much chromium in it. It is also very strong, which is why knives and turbine blades are made from it.
• Duplex: This is the combination of austenitic and ferritic steels that is both strong and flexible. It has twice the yield strength of austenitic stainless steel and is used a lot in industries like paper, pulp, shipbuilding, and petrochemicals.
• Precipitation: This type of stainless steel is just as resistant to corrosion as austenitic metals, but it can be made even stronger by adding things like aluminum, copper, and niobium.

Key Differences Between Stainless Steel and Carbon Steel

Can Stainless Steel Be Welded to Carbon Steel?

While it is technically possible to weld stainless steel to carbon steel, it is generally not recommended. The primary challenge lies in their differing electrical conductivity levels. Carbon steel is more electrically conductive and heats up slower than stainless steel during resistance welding, often requiring preheating. This makes achieving the correct weld temperature and a strong bond difficult. For better results and reduced complications, it is advisable to weld steels of similar types rather than combining dissimilar metals like carbon and stainless steel.

Carbon Steel vs Stainless Steel: Which Material Fits Your Application?

Should I Pick Carbon Steel or Stainless Steel?

Carbon steel and stainless steel are not the same, but that doesn't mean that one is better than the other. It depends on what is going on. Each material has its own pros and cons. The key is to find the right steel for the job.

High Carbon Steel

• Vulnerable to rust
• Brittle
• Wear-resistant

Stainless Steel

• Resistant to rust
• Less brittle
• Less wear-resistant

If you need more detailed guidance on whether carbon steel or stainless steel is right for your application, or if you require a quote for a custom project, please feel free to contact Amardeep Steel Centre.