What is Steel

Steel is a metal and an alloy of carbon and iron. Carbon content generally ranges from 0.2%-2.1%. This combination makes steel much stronger and harder than pure iron. Iron is the main component in steel composition. Steel is malleable (the ability of a material to be rolled into thin sheets).

Types Of Steel

One reason steel is so valuable is its ability to transform into countless forms. Some of the major types include.

1.   Carbon steel

2.   Alloy steel

3.   Stainless steel

4.   Tool steel

1. Carbon steel

Carbon steel is defined as steel that has its properties mainly due to its carbon content and does not contain more than 0.5 percent of silicon and 1.5 percent of manganese. The plain carbon steels, which range from 0.06 percent carbon to 1.5 percent carbon, are divided into three types:

• Low-carbon steel
• Medium-carbon steel
• High-carbon steel

• Low-carbon steel(mild steel)

Low-carbon steel contains about 0.5%-0.25% carbon. It includes a very low amount of carbon content. It is relatively soft, ductile, and easily shaped. It is used in car bodies, pipelines, and structural applications.

• Medium-carbon steel

It contains 0.325-0.60% of carbon content. It gives strength and ductility( a metal or material that can be bent or stretched easily). It is used in applications like railway tracks, crankshafts, and gears.

• High-carbon steel

It contains about 0.6%-1.4% carbon. This type is different from the two types mentioned above. High-carbon steel is not only very strong and hard but also very brittle. It is used in high-strength tools, springs, and cutting tools.

2. Alloy steel 

Steel is an alloy of iron and carbon. Still, alloy steel usually only refers to steels that contain other elements— like vanadium, molybdenum, or cobalt—in amounts sufficient to alter the properties of the base steel. In general, alloy steel is alloyed with various elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties. It is used for pipelines, pressure vessels, and automotive components. 

There are two main types of Alloy Steel,

  Low-alloy steel

Low-alloy steels constitute a category of ferrous materials that exhibit mechanical properties superior to plain carbon steels, resulting from the addition of alloying elements such as nickel, chromium, molybdenum, manganese, and silicon. The role of the alloying elements is to increase hardenability to optimize mechanical properties and toughness after heat treatment. However, alloy additions sometimes reduce environmental degradation under certain specified service conditions.

 High-alloy steel

Steels with alloying greater than 5 wt% are typically classified as high-alloy steel. Stainless steels are the major types of high-alloy steels, but two other types are ultrahigh-strength nickel-cobalt steels and maraging steels. Stainless steels are low-carbon, high-alloy steels with at least 10.5% chromium with or without other alloying elements.

3. Stainless steel

Stainless steel grades are alloyed with 10–20% chromium, nickel, silicon, manganese, and carbon. Because of their increased capacity to survive adverse weather, these steels have phenomenally high corrosion resistance and are safe for outdoor construction. Stainless steel grades are also commonly used in electrical devices.

There are three types of stainless steel,

1.   Austenitic stainless steel.

It is highly known for its high corrosion resistance and is non-magnetic.

Commonly used in kitchen utensils, piping, and medical devices.

2.   Martensitic Stainless steel.

It is known for its hardness and strength.

It is used in cutlery and surgical instruments.

3.  Ferritic Stainless steel.

Like austenitic stainless steel, it is also good for corrosion resistance.

It is used in automotive exhaust systems. 

4. Tool Steel

Tool steel is a type of carbon alloy steel. It is often used to make, modify, or repair hand tools or machine dies. Tool steel can retain its shape at high temperatures. Tool steel contains varying amounts of elements like tungsten, molybdenum, vanadium, and cobalt to enhance its Durability, resistance to deformation, and overall strength.

Types of Tool Steel:

1. Water hardening tool Steel(W-Series)

Water-hardening Tool steel is made of high carbon content, which makes it very hard.

It is used in tools requiring high hardness but not operating at high temperatures, like simple hand and cutting tools. 

2. Cold-work tool steel

Cold work tool steels are used in applications that work at room temperature.

3. Hot-work tool steel

Hot-work tool steel contains different metals, such as chromium, tungsten, or molybdenum. It is designed in a special way to withstand high temperatures without losing hardness or strength.

4.High-Speed tool steel(T-Series and M-Series)

It is also known for maintaining hardness at very high temperatures. It is commonly used in cutting tools like drill bits, milling cutters, and saw blades.

T-Series=Tungsten-based, it retains hardness at high temperatures.

M-Series=Molybdenum-based. It is more cost-effective than the T-series and highly resistant to softening at high temperatures.

5. Shock-Resisting Tool Steel

It is designed to withstand sudden and repeated impacts. It is used for tools that experience high impact, such as chisels, hammers, and punches.

Properties Of Steel

Researchers are continually developing new methods to make steel lighter, stronger, and more environmentally friendly. Innovations such as high-strength steels, advanced coatings, and sustainable production methods aim to reduce carbon emissions and enhance sustainability.

1.   High strength and Durability.

Steel is strong and can withstand high-stress levels, making it suitable for construction, infrastructure, and industrial applications.

2.   Toughness.

Steel has high impact resistance, making it suitable for structures exposed to dynamic loads and harsh environments.

3.   Corrosion Resistance.

Stainless steel contains chromium, which forms a protective oxide layer, increasing corrosion resistance. Regular steel can corrode but may be treated or coated to improve this properly.

4.   Density

Steel has a density of about 7.85 g/cm, which is relatively heavy, impacting its use in lightweight.

5.   Ease of Fabrication

Steel can be welded and machined, allowing for manufacturing and construction versatility. Steel properties vary widely depending on its composition, e.g., carbon content, alloying elements, heat treatment, and mechanical processing. This makes steel suitable for applications ranging from construction to medical instruments. 

What is the difference between stainless steel and mild steel?

Conclusion

Each type of steel has unique properties suited to specific applications, making it more versatile in engineering and industry.

Tool steel is widely used in automotive, aerospace, construction, and manufacturing industries, where precision tools are essential.

Steel remains central to engineering solutions and progress in countless fields as advancements continue.