Steel is an alloy. An alloy is a material that is made up of two or more metals. The main metal however is iron with few percent of carbon to improve its strength and fracture resistance compared to iron. Many other additional elements may be present or added. Stainless steels that are corrosion and oxidation resistant need typically an additional 11% chromium. Manganese is also frequently present in steels. Here, we are going to discuss the steel and its tensile importance.
CLASSIFICATION OF STEEL
Steel is generally classified into two main categories:
- Dead Mild Steel:
Steel with carbon content less than 0.15% is known as deal mild steel. It is used in roofing, machine parts and in reinforcing pre-stressed concrete structures.
- Mild Steel:
Steel with carbon content from 0.15% to 0.30 %. is called mild steel. It is used in construction as rolled sections, rail tracks, towers and in manufacturing of various tools.
- Medium Mild Steel:
Steel with carbon content from 0.30 % to 0.55 % is medium mild steel. It is used as reinforcement in plain cement concrete to provide tensile strength and it is also used as round bars.
- High carbon Steel:
High carbon steel has carbon content from 0.55 % to 1.5%. it is used in drills, files, chisels and in parts of machines required to withstand shocks and vibrations.
- Stainless Steel:
Steel with chromium over 16 % and possibly some small percent of copper. It is used in all applications involving corrosion resistance.
- Nickle Steel:
Steel with 3.5% Nickle and 0.5 to 1.0 % of carbon. This steel is used in automobile parts, airplanes and propeller shafts.
- Vanadium Steel:
Steel with 0.1 to 2.0 % of vanadium. It is very strong as well as ductile and is used in high tech applications.
- Tungsten Steel:
Steel containing 14 to 20 % Tungsten and small amount of chromium and carbon. It is used in drilling machines and high-speed cutting tools.
- Manganese Steel:
Steel with 12 to 15 % manganese. It is used in machine parts, points and crossings in rail tracks.
UNDERSTANDING TENSILE STRENGTH
The tensile strength of a material is the maximum stress that can be applied to it before it breaks. In other words, the maximum stress or load a material can withstand.
For us to get a better picture of what tensile strength is, let us look at it in comparison with compressive strength. Compressive strength in construction refers to the physical property of different building materials and how they can withstand compression and pressure. Compression strength defines the load-bearing capabilities of a material (like steel and concrete) and a particular part of a building (like foundations and load-bearing pillars).
Tensile strength, on the other hand, refers to the physical property of different building materials and how they can withstand tension. Tension strength defines how well a building material (like concrete or alloys) and a part of a building (like exterior walls and elevator shafts) behaves when external forces such as wind and gravity act on it.
THE TENSILE STRENGTH OF STEEL
Studying the tensile strength of a building material allows architects and engineers to build skyscrapers in a safe and efficient manner. It is also sometimes necessary to be able to alter the properties and tensile strengths for certain applications.
Steel is one of the best materials in terms of tensile strength vs compressive strength. A metal’s yield strength and ultimate tensile strength values are expressed in tons per square inch, pounds per square inch or thousand pounds (KSI) per square inch. For example, a tensile strength of a steel that can withstand 40,000 pounds of force per square inch may be expressed as 40,000 PSI or 40 KSI (with K being the denominator for thousands of pounds). The tensile strength of steel may also be shown in MPa, or megapascal.
To make sure that structures stand the test of time, gravity, and normal wear-and-tear, engineers will choose materials with high-tensile strength. Steel is best for this purpose. Concrete is very much brittle, which means that, while its great for low-rise buildings because it does not encounter high winds, it doesn’t stand well against the wind currents on higher floors. Without reinforcement, the concrete would break and shatter when it goes up against strong winds. So, for relatively large buildings, it is a “must” to use steel reinforcements for construction.
Engineers use a variety of reinforcement techniques, such as melding steel bars onto to the concrete to give it more tensile strength or installing counterweights inside the building to give it more balance and stability during high winds.
This vital application of steel makes it one of the most important materials in civil as well as other fields of engineering and has proved to be a progenitor of the modern world.