Difference Between Corten Steel and Mild Steel

by AMC

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Posted on November 24, 2022 at 04:52 PM

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What is Mild Steel?

Mild steel, also known as carbon steel, is the most prevalent type of steel today. Mild steel is less expensive and, once sealed, will keep a naturally rusty appearance. known as Penetrol. This maintains the color and appearance of the rust. Low-carbon steel contains between 0.05 and 0.25 percent carbon, rendering it malleable and ductile. Carburizing can be used to increase the surface hardness of mild steel, which has a relatively low tensile strength but is inexpensive and simple to form.
It is frequently used when large quantities of steel are required, such as for structural purposes. Mild steel has a density of approximately 7.85 g/cm3 (7,850 kg/m3 or 0.284 lb/in3)

The following chart shows the differences and characteristics of the three steel types:

	Carbon content (wt. %)	Microstructure	Characteristics	Examples
Low-carbon steel (Mild steel)	Less than 0.25	Pearlite, ferrite	Soft, cheap, very ductile, easy to machine and weld	AISI105, AISI 316L, Q195, Q215, Q235, 08F, 15Mn, 20Mn
Medium-carbon steel	0.25 to 0.60	Martensite	Reasonably ductile, hard, strong and not easy to harden	AISI 409, 45#, 40CR, 20CR, SCM 435
High-carbon steel (carbon tool steel)	0.60 to 1.25	Pearlite	Very hard, strong, unyielding, hard to machine and weld	T7, T7A, T8Mn, T8MnA, AISI440C

What is Corten Steel?

Corten steel (commonly abbreviated as Cor–Ten) is a weather-resistant steel that is more precisely known as "Atmospheric Corrosion Resistant Steel." It is a steel alloy including copper and chromium; this alloy is more resistant to atmospheric weathering than other unalloyed steels. Under the influence of the weather, the steel produces a protective layer on its surface.

The unique distribution and concentration of alloying elements in the protective layer are responsible for its corrosion-inhibiting properties. The surface-protecting layer forms and regenerates continually under the influence of the elements. In other words, the steel is allowed to rust so that a "protective" layer can form.

Chemical Properties of Mild Steel

Chemical composition (Ideal analysis to meet the majority of grades listed above)
Carbon	0.16-0.18%
Silicon	0.40% max
Manganese	0.70-0.90%
Sulphur	0.040% Max
Phosphorus	0.040% Max

Chemical Properties of Corten Steel

	Content, % (ladle analysis)
	C (max)	Si	Mn	P	S (max)	Al	V	Cu	Cr	Ni (max)
Corten A	0.12	0.25–0.75	0.20–0.50	0.07–0.15	0.030	0.015–0.06	–	0.25–0.55	0.50–1.25	0.65
Corten B	0.19	0.30–0.65	0.80–1.25	0.035 max.	0.030	0.020–0.06	0.02–0.10	0.25–0.40	0.40–0.65	0.40

Mechanical Properties of Mild Steel

As shown in the chart above, mild steel has less carbon than other carbon steels. Mild steel contains 0.25 percent carbon.

Mild steel provides high impact strength, excellent ductility and weldability, and the ability to be cold-formed. Due to these characteristics, mild steel is easier to CNC machine than other forms of steel.

Mild steel has a relatively low tensile strength, which makes it more susceptible to breaking than other steels.

Carburizing, a form of heat treatment, can be utilized to increase tensile strength. Carburizing is a surface-hardening process in which mild steel is heated to a given temperature and then cooled, which hardens the surface of the steel while leaving the core flexible and ductile.

Mechanical Properties of Corten Steel

The mechanical properties and thickness ranges of Corten steel are provided in the following table.

	Thickness (mm) Strip Products	Plate Products	Yield strength minimum	Tensile stength minimum	Elongation miniumum
Corten A	2 – 12	6 – 12	345	485	20
Corten B	2 – 13	6 – 40	345	485	19

Applications of Mild Steel

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Use of mild steel is widespread. Examples of typical uses include hardware tools, cookware, medical instruments, machinery, construction, and infrastructure.

1. Construction and infrastructure

Mild steel provides excellent tensile strength for use in construction frames. Mild steel meets seismic and wind standards, is impervious to worms and insects, and is erodible and fire-retardant, making it ideal for construction.

2. Machinery

Due to its high strength, ductility, and hardness, mild steel is favoured for the production of machine accessories. Due to the low carbon content, the steel is machineable, cuttable, pressable, moldable, and formable without breaking.

3. Cookware

Mild steel is preferred for making machine accessories because to its high strength, ductility, and hardness. Due to the steel's low carbon content, it may be machined, cut, pressed, shaped, and formed without breaking.

4. Pipelines

Due to the extreme ductility of mild steel, mild steel pipes are widely used in the production of various types of pipes and poles. Mild steel could be utilized as a food-safe material, therefore steel pipes are great for transporting water, beverages, and natural gas. As a result of their low carbon content, outdoor pipes are resistant to rust and harsh weather. Mild steel pipes are much more durable and environmentally friendly than plastic pipes. It can also be cut into a rectangular shape.

Corten Steel Applications

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1. Landscape and Garden Design:

There are many methods to shape and enhance an outdoor area using weathering steel, from landscape edging to planter boxes. In fact, cor-ten was recently listed as a top trend in landscape design by The Wall Street Journal.

2.Roofing and Siding:

Produced from ASTM A606-4 and A588 , weathering steel corrugated and profile panels are widely used to construct roofs and building facades. For instance, the Amardeep Steel Center building was created out of cold-rolled weathering steel. The building’s exterior facade was constructed from ASTM A606-4 corrugated and rib panels.

3.Sign Posts:

Corten Steel (Weathering steel) sign posts are designed to endure 30 years longer than your typical steel posts since they develop the protective patina. Plus, they look amazing in natural situations! Weathering steel sign posts are typically used for traffic signs and vineyard end posts.

4.Security Solutions:

Gates, fences, and bollards are just some of the security applications where corten steel shines. The rusty patina that corten steel develops over time makes it an excellent choice for use in playgrounds, parks, farms, and vineyards, among other outdoor settings.

5.Outdoor Sculptures:

These days, you're more likely to see sculptures made of weatherproof steel in public spaces. corten steel is used by numerous sculptors because of its durability, versatility, ease of fabrication, and aesthetic appeal.

Most Common Mild Steel Grades

Here are some of the most common grades of Mild steel. All of them and other metals like them have the quality of being universal. Because of how they work, they are used in a wide range of situations.

EN 1.0301

Equivalent grades: AISI 1008; C10; DC01 EN 1.0301 carbon steel contains 0.1% carbon, 0.4% manganese and 0.4 percent silicon. It also contains small amounts of copper (Cu), nickel (Ni), chromium (Cr), aluminum (Al), and molybdenum (Mo). This grade is easy to weld and is often used for parts and shapes that are extruded, forged, cold headed, or cold pressed. It is mostly used in car parts, furniture, and home appliances.

EN 1.1121

Equivalent grades: AISI 1010 EN 1.1121 carbon steel has between 0.08% and 0.13% carbon in it. Manganese is found in amounts between 0.3% and 0.6%. It is used to make bolts and screws with cold-headed heads. This grade is also easy to shape and bend, and it can be shaped using traditional techniques. It also works with all kinds of welding techniques. Heat treatment, quenching, and tempering can be used to make it stronger, but these steps are expensive to do. It is a general-purpose steel that is used a lot in buildings and the car industry.

. EN 1.0402

Equivalent grades: AISI 1020; C22 This type of steel is very easy to weld. EN 1.0402 is especially good for parts that will be carburized. It is also a good mix of being flexible, strong, and tough. It has between 0.18% and 0.23% carbon and between 0.3% and 0.6% manganese. Compared to EN 1.1121, it is not used as much, but in its as-forged state, it is very easy to machine. This grade is used to make hydraulic parts and camshafts for machines.

Most Common Corten Steel Grades

Corten A

This version contains added phosphorus making it more suitable for flue gas applications. Corten A is not recommended for heavy-load bearing applications as the added phosphorus reduces its tensile strength.

Corten B

Corten B is used more often than the other type.
It is the one that forms the rust coating and keeps a high level of tensile strength while still being pliable enough to weld.
Corten B is great for steel parts that will be used in heavy, load-bearing structures outside in harsh conditions.
Your metal manufacturer will help you decide which of the two versions is best for your project based on your specific needs.

Advantages of Corten Steel

1.Little to No Painting

The patina that forms on corten weathering steel makes it less likely that it needs paint, and in most cases, it doesn't even need paint.
This not only saves money on maintenance and materials, but it also keeps you from using some paints' dangerous and volatile chemicals.

2.Strong and Durable Material

Corten's (Corten B) high tensile strength and durability make it a good choice for heavy-duty structures that carry a lot of weight.
Traditional steel is four to eight times less strong than weathering steel.

3.Attractive Rustic Appearance

The reddish-brown rust that naturally forms on its surface makes it a popular choice among architects and design engineers who work on artistic and modern structures and applications.

4.Very Little Upkeep and Maintenance

Because of the way it is made, corten steel can stand up to wet, humid, and hot conditions that would damage other types of steel.
Corten's melting point is around 1450-1510 degrees Celsius.
Corten weathering steel can be used to make structures that will last for a long time. There is little to no maintenance needed, so less money is spent on upkeep.

5.Environmentally Compliant and Friendly

It still meets most building standards and codes because it is made of eco-friendly materials that are 100% recyclable.
So, it's a good choice for people who want to build with materials that are good for the environment.

Advantages of Mild Steel

1.Strength to Weight Ratio

Mild steel is one of the lighter metals you can use. It is lighter than other grades of carbon steel and most other types of steel. This is because the main thing that affects the weight of these metals is how much carbon they have.
Even though it is lighter, its strength-to-weight ratio is still very good. It is a strong and tough metal. This makes it a reliable steel for making things out of metal and a much easier material to work with when making things.

2. Weldable

One of the best things about mild steel products is that they can be welded. Mild steel is easier and faster to weld than other types of carbon steel. This is because mild steel is an easy metal for electric currents to move through without changing the metal's "make-up."
This is a problem with some other kinds of steel, like stainless steel. When it comes to welding, these materials may need special techniques, but mild steel can be worked with much more simply and for less money. This makes it easy to work with during the making process.

3.Favorable Chemical Properties

Mild steel can be made with many different things besides iron and carbon. No matter what combination manufacturers choose, it will change the chemical properties of the steel and make it better for some uses than others.
Mild steels often have chromium, manganese, sulfur, phosphorus, copper, and cobalt added to them. Each one can make some chemical properties stronger. The main goal of alloying is to make something stronger against heat, corrosion, and wear.
For example, mild steel that has more chromium makes it harder and less likely to rust. This is great for uses where the metal can stand up to air and water without getting rusty. Copper is another element that can be used to make mild steel stronger. It has a similar effect on mild steel and is often used to make pipes and tubes.

4.Ductile

The ability of a metal to be stretched and bent in a plastic way is measured by its ductility. For the metal to be ductile, it needs to be able to do this without breaking. For a metal to be considered ductile, it should be able to be deformed around 15% without breaking. After that, it can't go back to its original shape.
Mild steel is one of the more malleable metals you can use for your project in this way. Even when a fairly large force is put on it, it can bend and stretch without becoming permanently changed. They are easy to shape, bend, and weld because of this quality.

5. Cost-effective

Mild steel is one of the steel grades that costs the least. This makes it a cheap way to make things that people use every day, like car frames, steel pipes, and even cookware.
It costs much less than other kinds of steel because it has a low amount of carbon. So, if you have a smaller budget, mild steel might be the best option for you. When a lot of this metal is needed, it can be made quickly and cheaply in large quantities, unlike other steel products.
Extra treatment is one of the few things you have to think about when figuring out how much it will cost. For some uses, mild steel needs to be galvanized or heat-treated to make it less likely to rust. Even so, it is usually cheaper than other materials.

Conclusion

The best thing about Corten weathering steel is that it doesn't rust in the weather.

The protective layer of rust that forms on its surface when it is exposed to the elements is the cause of these qualities.

In addition to being able to rust, it also has a high level of tensile strength, can be welded, and can be machined.

That makes it a good choice for big building and construction projects outside.

Artists, sculptors, architects, and design engineers who need a natural-looking material for their work like the way it looks old and worn.

Corten steel is the best choice if you want a material that doesn't rust, has high strength, is flexible, is easy on the eyes, doesn't need a lot of care and maintenance, and is friendly to the environment and meets all the rules.

Mild steel, also called low-carbon steel, has less than 0.25 parts per million of carbon. Mild steel is used in almost every industry because of how it works. CNC machining is a common way to make prototypes or low-volume production-quality parts out of mild steel. Metal injection molding is a better way to make larger amounts.

Amardeep is a professional prototype and low-volume production service. They have many years of experience and know how to machine different kinds of carbon steel, Corten steel, stainless steel, alloy steel, etc.

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