What is steel?

Steel is an alloy of carbon less than 2%, and manganese is 1%, with small amounts of phosphorus, oxygen, silicon and sulphur. Carbon will not only increase the strength of the alloy but also provides resistance to cracks. Steel is used to produce from needles to high-end machinery and parts in rockets too. Stainless steel is another form of steel where 11%of chromium is used to make its oxidation and corrosion resistant. Steel is available at low cost and possesses high tensile strength. Iron is the base metal in steel. Steel has two crystalline structures, which depend on the temperature of body-centred cubic and face-centred cubic structures.

How is steel produced?

Prior to the 17th century, steel was produced in a bloomery furnace. A blast furnace was created in the 19th century to produce industrial steel. Nowadays, steel is one of the most produced materials in the world. Steel is mainly prepared in two ways: a blast furnace basic oxygen furnace (BF BOF), and an electric arc furnace(EAF). The only difference between the two ways is raw material.

• In BF-BOF, they use coal, recycled steel and iron ore, while in EAF, they use electricity and recycled steel or direct-reduced iron(DRI) or hot metal. Nearly 70% of steel is manufactured in the BF-BOF method.
• In the BF-BOF method, iron ore is reduced to iron (also known as pig iron or hot metal). The iron is then converted into steel. In the EAF method, electricity is used to melt recycled steel in the presence of oxygen, and additives like alloys are used to get the desired composition of the steel. In this method, we can produce up to 30%of steel.

Both BF-BOF and EAF methods are updated to produce the steel environmentally friendly.

Steel is produced in another way called OHF or open hearth furnace method. Very small amounts of steel are produced in this method, and a high amount of energy is used, which is a major drawback.

Properties of steel

Steel is used in many ways because of its peculiar properties and is available at a low cost compared to other building materials like concrete, wood, and cast iron. Let's look at the important properties of steel.

1. Tensile strength:

Tensile strength means the resistance of a metal to break down under tensile stress. Tensile strength makes us know how far steel can be shaped and where we can see brittle failure. Structural steel's Tensile strength is 400megapascals (MPa),& carbon steel is 841MPa. Tensile strength varies for different types of steel.

2. Yield strength:

Yield strength is the capability of a material to deform plastically under maximum stress. Yield strength helps identify how much pressure is needed to change a metal's shape. Yield strength for steel is 350MPa

3. Hardness:

Hardness is the ability of a substance to withstand surface indentation and scratch. The hardness of steel is measured with a Brinell hardness test. Hardness for low carbon steel 120MPa, for high carbon steel 200MPa.

4. Malleability:

Malleability is a metal's ability to be distorted below compression strength. Steel has high malleability.

5. Ductility:

It is measured as the amount of tensile stress of a material before it deformed in shape. Steel with low carbon composition will tend to have more ductility when compared to other types. High carbon composition steel has higher ductility and is harder.

6. Corrosion Resistance:

Different metals have different ranges of corrosion resistance. Corrosion is a chemical reaction between the metal and its surroundings, generally with oxygen, and the metal will degrade over time. Stainless steel is the best corrosive-resistant steel type. Corrosion will accumulate oxygen nearly twice the thickness of the substance.

7. Elongation:

Elongation means the stretching of an element than its original length. Steel Elongation at Break is 15%. If an element is 10 cm long and it is elongated to 15 cm prior to fracture is called elongation strength, and in this case, it is 50% as the element is elongated half of its length.

In steel, more than 3000 types are present depending on the chemical, physical and environmental properties.

Types and Grades in steel with prices:

1. Alloy steel:

The iron is mixed with other elements in Alloy steel to provide extra strength. All steels are known as alloys. Alloy steel consists of aluminium, molybdenum, silicon, manganese, vanadium, etc.

Price: Alloy steel pipe price- 130/kg. The price range starts from Rs60, and depending on size and length, the price varies.

2. Tool steel:

High carbon content is present in tool steel apart from tungsten and molybdenum. It is formed by exposing it to high heating and cooling instantly. Tool steel is very abrasive. There are more than 5types of tool steels. Tool steel is used in making tools in the industry.

Price: Tool steel blocks price starts from 400/Kg. Round bars of tool steel price start from 200/kg

3. Stainless steel:

Steel is alloyed with chromium to create stainless steel. It is rust-resistant steel. This type is mostly used in preparing kitchen and medical appliances. It is available in different types depending on their composition and usage, like Martensitic alloys, Austenitic alloys, and Ferritic alloys.

Price: It is mostly available in strips, and the price starts from 150 depending on the thickness and length price varies

Note: Prices may vary depending on the market so please verify prices before buying.

4. Carbon steel:

Carbon steel contains carbon 1% and manganese 1.65%. This is the most common type available in the market. Depending on the carbon content, it is subdivided into 3 types ( up to 0.3%) low carbon steel, (0.3-0.6%) medium carbon steel and (more than 0.6%) high carbon steel. It is affordable, strong, produced on a large scale, and used in construction.

According to the American steel industry, steel is categorised into two grading systems are present they are:

1. American Society for Testing and Materials(ASTM): uses alphanumeric classification.

2. Society of Automotive Engineers(SAE): uses four-digit classifications to denote steel type, carbon content, and other alloys.

In India, steel grading depends on

• Chemical composition: Fe 330, Fe 410, and Fe 450
• Mechanical properties they are:

Grade I
Grade II
GradeIII
Grade IV and
Grade V

Benefits of quality steel

Steel is used in the construction industry and has many benefits

• Structural steel is used to build high-rise buildings. It is resistant to earthquakes and external winds.
• Steel is cost-effective and available readily in the market, which saves time
• Used steel can be recycled, thus making it environmentally friendly.
• Steel possesses high strength and is lightweight.
• It is durable, ductile, and fire-resistant.
• It is convenient to construct temporary structures.

 

 

 

Conclusion

In this blog, we have discussed steel, its production types and grades, and quality steel's benefits. Steel is used in construction for supporting structures and temporary staying constructions. Its wide range of composition and characteristics is used to produce from hairpins to industrial equipment.