Types of Steel and Their Properties
Mankind began working with iron some 6,000 years ago. After it, steel production began. Steel is widely employed in everyday life, including in kitchenware, building, the medical area, and electrical appliances, among other things. Do you believe all of these items are made of the same type of steel? There are various varieties of steel that are adjusted to meet the needs of a specific product's production.
What is Steel?
Steel is an iron alloy that is largely made up of iron and other alloys that give it its distinct qualities. Steel is categorized into four classes, each of which is further segmented for specific purposes. These are the four varieties of steel.,
Carbon steel
Stainless steel
Alloy steel
Tool steel
Along with these types let us learn about types of steel bars, types of steel used in construction, and their properties.
Types of Steel and their Properties
Carbon Steel
All varieties of steel contain carbon, but carbon steel is distinguished by the absence of many additional components. Despite the fact that this steel has a carbon content of roughly 2%. Its elemental nature makes it strong and resilient, allowing it to be employed for a variety of purposes. Carbon steel and cast iron are frequently mistaken; however, the carbon content of each may be distinguished. The carbon content of carbon steel affects its characteristics.
Types of Carbon Steel:
It is subdivided depending on the carbon content, where it gets increased in each type.
Low Carbon: It is the most often used and the least priced variety. It is simple to make since it is very ductile and can be stretched under tension. Wires, pipes, and bolts are all made from it.
Medium Carbon: This grade of steel has a carbon content of 0.31 to 0.6 percent. This is why they are extremely strong and have a low ductility. They're utilised to construct railway rails and gears.
High Carbon: It has a carbon content of greater than 0.61 percent. It's used to manufacture brick nails as well as trencher blades and other sharp cutting nails.
Stainless Steel
Medical equipment and appliances frequently use stainless steel. The element chromium is utilised in the manufacture of stainless steel. Because this element is resistant to oxidation, it contributes to the metal's durability by preventing rusting. Depending on the application, chromium concentration might range from 10.5 percent to 30 percent. The higher the chromium concentration, the more glossy it appears and the more corrosion resistant it is.
Types of Stainless Steel:
It is commonly used in medical, kitchen, and automotive products.
Martensitic Alloys: Toughness is a distinguishing feature of these alloys. These are generated as a result of rapid cooling, making them perfect for the heat treatment process. Medical devices, pliers, and cutlery all include them. They are, nevertheless, prone to corrosion.
Ferritic Alloys: These alloys are less expensive because they include low levels of carbon and nickel. They are employed in automotive applications because of their high chromium induced strength and gloss.
Austenitic Alloys: These alloys have a greater nickel and chromium concentration. As a result, their corrosion resistance has grown, and they are non-magnetic in nature. They are utilised in culinary utensils because they are robust and easy to clean.
Duplex Alloys: It's a ferritic and austenitic alloy mixed together. It inherits both types' properties while doubling their strength. They are ductile and have a good corrosion resistance.
Alloy Steel
When iron is fused with a variety of other elements, each one contributes to the end result. All steels are alloys, but only a few of them have distinct names. It comprises a wide variety of alloys with similar properties. The qualities of various alloy steels allow them to be modified for specific uses. The second element in the mix, on the other hand, requires a high price. The following are the most regularly used alloys:
Aluminium: They are lightweight, highly resistant to heat, and ductile. Hence they are used in hot exhaust systems and power generators.
Copper: They are good conductors of heat and resistive to corrosion. Thus they are choosed in making of electrical wires and industrial heat exchangers.
Manganese: Due to its extremely tough quality they are used in bullet proof cabinets and anti-drill plates.
Molybdenum: It is resistant to corrosion, weldable and it can perform under higher pressures. Thus suitable for oil and gas pipelines and for underwater construction.
Silicon: It is a soft-natured steel, that is highly malleable and magnetic. They are used to make strong magnets and used in electrical transformers.
Vanadium: It is the high impact steel that resistant to vibration and shock-absorbent. It is used in automotive parts such as ssprings and shocks.
Tool Steel
By tempering the process of adding high heat, cooling it quickly, and heating again makes the tool steel. It is extremely hard and resistant to heat.
Air Hardening: Due to the high chromium content in this steel it makes the ideal for the exposure to high temperatures.
Water Hardening: While using this type of steel it undergoes a water quenching process. It is the most affordable type and used to make common tools.
Oil Hardening: This type of steel is quenched in oil. It is wear resistant from slipping. Hence it is used to make knives and shears.
Hot Working: This type of steel can withstand high temperatures and hence used in forging and casting.
Shock resisting: It is hard in nature hence used in manufacture of punches and riveting tools.
Types of Steel Bars
There are five types of steel bars:
Hot Rolled Deformed Bars: they are also known as thermo-mechanically treated bars or TMT bars. These are used for superior strengths in the concrete structures. It consists of ribs that help them to hold the concrete firmly.
Cold Rolled Steel Bars: Even though they are made at room temperatures, they look similar in structure as of hot rolled steel bars. They are poor in strength and can be bent into any shape. They are used in construction where high tolerance is not required.
Mild Steel Bars: These steel bars have a plain surface and are circular in nature. They are used in concrete structures as beams and slabs. They are poor in quality and cannot blend well with concrete as hot rolled bars. Thus it is used in budget constraints and small projects.
Twisted Steel Bars: They are also called prestressing tendons. They are made of different wires. About seven wires are spinned to form a single strand. It has high tesile strength.
Welded Steel Wire: These consist of a weld mesh that provides medium strength. They are used while partitioning or in fencing. It is available in different diameters and is said to be strong compared to mild steel. Due to this reason it is widely used for construction for efficiency.
Due to its high tensile strength the widely accepted and used steel bars worldwide are TMT bars. Along with providing the strength they are flexible too. Thus it can provide its maximum protection against any kind of natural disasters such as earthquakes, floods etc. As they have less content of carbon they are highly resistant to corrosion.
Types of Steel Used in Construction
Light Guage Steel: Based on teh specific standards it is made from thin sheets. Using cold deformed steel it can be used to make steel frame system. It is flexible and safe to use. It is one of the different types of steel that is used in flooring.
Structural Steel: It is one of the most important and frequently used type of steel in construction where it is used to provide base or structural support. It is available in different shapes and sizes, few examples include I-beam, plate type, T shaped etc.
Mild Steel: It is a plain carbon steel that is known for its strength. It is used in both conventional and pre-engineered buildings.
Rebar Steel: It is a reinforcing steel, that reinforces the structure that fixes with the concrete. For the building purposes it is used in the form of a mesh. These can also be manufactured for long lengths.
Conclusion
With average minimum prices, with unique combinations, different types and with various properties the steel industries are found booming. These qualities make them to be used in various applications.
FAQs on Steel Industry is Booming!
1. What is steel, and how is it chemically different from iron?
Steel is an alloy of iron with a small, controlled amount of carbon, typically between 0.02% and 2.1% by weight. The primary chemical difference is this addition of carbon, which fits into the crystal lattice of the iron atoms. This alters the material's properties significantly, making steel much stronger and harder than pure iron, which is a relatively soft and ductile element.
2. What are the main types of steel based on their carbon content?
Steel is primarily classified into three main types based on its carbon content, which directly influences its mechanical properties:
Low-Carbon Steel (Mild Steel): Contains up to 0.3% carbon. It is ductile, weldable, and relatively inexpensive, used for car bodies, pipes, and structural shapes.
Medium-Carbon Steel: Contains 0.3% to 0.6% carbon. It has a good balance of strength, hardness, and ductility. Examples of its use include railway tracks, gears, and crankshafts.
High-Carbon Steel: Contains more than 0.6% carbon. It is very hard and strong but less ductile, making it suitable for cutting tools, springs, and high-strength wires.
3. What is the importance of adding alloying elements other than carbon to steel?
Alloying elements are added to steel to enhance its properties for specific applications, creating what are known as alloy steels. The importance of these elements is to impart desired characteristics. For example:
Chromium (Cr): Provides excellent corrosion resistance and hardness, which is the key to making stainless steel.
Nickel (Ni): Increases toughness, strength, and acid resistance. It is often used with chromium in stainless steels.
Manganese (Mn): Improves hardness and resistance to wear without making the steel brittle.
Tungsten (W): Retains hardness at high temperatures, making it essential for high-speed cutting tools.
4. What is stainless steel, and what makes it resistant to rust?
Stainless steel is a specific type of steel alloy that contains a minimum of 10.5% chromium by mass. Its remarkable resistance to rust and corrosion is due to this high chromium content. The chromium reacts with oxygen in the atmosphere to form a thin, invisible, and stable layer of chromium oxide (Cr₂O₃) on the surface. This passive layer acts as a protective barrier, preventing oxygen and water from reaching the iron underneath, thereby stopping the rusting process from starting.
5. How does the percentage of carbon fundamentally change the properties of steel at a microscopic level?
The percentage of carbon fundamentally alters steel's properties by changing its microscopic crystal structure. In low-carbon steel, the structure is mostly ferrite, a soft and ductile form of iron. As carbon content increases, a very hard and brittle compound called cementite (iron carbide, Fe₃C) begins to form alongside ferrite. This mixture, known as pearlite, makes the steel stronger and harder. In high-carbon steels, the proportion of hard cementite is much higher, leading to extreme hardness but reduced ductility.
6. Why is heat treatment essential for controlling the final properties of many steel products?
Heat treatment is essential because it allows for precise manipulation of the steel's microstructure after it has been formed, without changing its chemical composition. Different heat treatment processes achieve different outcomes:
Annealing (slow cooling) creates a soft and ductile structure, making the steel easier to work with.
Quenching (rapid cooling) freezes a very hard, brittle structure called martensite.
Tempering (reheating after quenching) reduces brittleness while retaining much of the hardness.
This control is vital for creating products like tools, blades, and machine parts that require a specific balance of hardness and toughness.
7. Compare the properties of steel to those of its parent metal, iron.
While steel is primarily made of iron, the addition of carbon creates significant differences in their properties:
Hardness and Strength: Steel is significantly harder and stronger than pure iron. Iron is relatively soft and malleable.
Ductility: Pure iron is more ductile than most steels. As the carbon content in steel increases, its ductility decreases.
Corrosion: Both iron and standard carbon steel are prone to rusting. However, steel can be alloyed with elements like chromium to create stainless steel, which has excellent corrosion resistance, a property pure iron lacks.
Versatility: By varying the carbon content and adding other alloying elements, the properties of steel can be tailored for thousands of applications, making it far more versatile than iron.
8. From a chemistry standpoint, what are the key reactions in the Basic Oxygen Steelmaking (BOS) process?
In the Basic Oxygen Steelmaking (BOS) process, the primary goal is to reduce the high carbon content of molten pig iron and remove impurities through oxidation. High-purity oxygen is blown over the molten metal, leading to key exothermic reactions:
Carbon Removal: Carbon reacts with oxygen to form carbon monoxide gas, which is the main refining reaction: 2C + O₂ → 2CO.
Impurity Removal: Impurities like silicon, manganese, and phosphorus are oxidised: Si + O₂ → SiO₂; 2Mn + O₂ → 2MnO; 4P + 5O₂ → 2P₂O₅.
Slag Formation: A basic flux, like calcium oxide (CaO), is added to react with the acidic oxides (like SiO₂ and P₂O₅) to form a molten slag (e.g., CaSiO₃), which floats on top and is removed.
