In brief, mild steel is a form of low-carbon steel. Although both are used commonly, there is a slight difference between them. Low-carbon steel refers to a broader category, while mild steel falls under this category. It has a trace amount of carbon ranging from 0.05-0.25%. Mild steel has become a crucial material in modern construction. Let’s explore the properties and uses of mild steel further.
What is Mild Steel
Mild steel is a type of steel alloy mainly composed of iron with a nominal carbon content (typically 0.05-0.25%). It has no other major alloying elements than carbon. Notably, mild steel is well known for its flexibility, adaptability, and weldability. It is bendable and stretchable for different construction purposes.
Properties of Mild Steel
Mild steel has diverse properties, which are explained below
Physical Properties
Density: Mild steel possesses a firm solidity with a density of 7.87 g/cm³.
Melting Point: Its optimal melting point range of 1420-1460°C facilitates easy welding and shaping.
Specific Heat Capacity: With a relatively low specific heat capacity of 510 J/kg. K, mild steel regulates room temperature and enables effective thermal storage systems.
Thermal Conductivity: It is an important aspect of industrial machines or systems. It needs to be high so that damage to machine parts will be avoided. Mild steel has high thermal conductivity (50-65 W/m-K). It makes them ideal for heavy machinery parts.
Magnetism: Mild steel is strongly magnetic as it contains high amounts of iron and has a ferrite structure.
Ductility: Mild steel is renowned for ductility so it facilitates trimming, welding, and shaping into desired shapes.
Malleability: Its mouldable nature enables various product manufacturing processes.
Yield Strength: 250-300 MPa is the range of yield strength set for mild steel. It shows its resistance to deformation.
Tensile Strength: Value between 350-480 MPa is expected as tensile strength in mild steel. It means that mild steel can ensure maximum load-bearing capacity.
Chemical Properties
Chemical properties refer to the reactions or qualities of elements used for steelmaking. Understanding chemical properties helps in assessing the overall performance of steel in adverse climatic conditions. As already mentioned, carbon steel has alloying elements in only trace amounts. Though less amount of carbon is beneficial for machinability, it is not corrosion resistant.
Some other elements like manganese, phosphorus, sulphur, and silicon are added in small quantities to enhance corrosion resistance properties. However, it can only provide resistance up to a minimal level. The carbon content of steel provides flexibility and elasticity, making it suitable for shaping.
Mild Steel Composition
Mild steel is majorly iron-based with small amounts of other elements. The composition contains
– Iron (98-99.5%)
– Carbon (0.05-0.25%)
– Manganese (0.5-1.5%)
– Silicon (0.1-0.5%)
– Phosphorus and sulphur: very small amounts
– Other metals (like chromium, nickel): trace of amounts
This composition gives mild steel strength, adaptability, and ease of shaping.
Applications of Mild Steel
Construction
Mild steel has high tensile strength, so it can withstand heavy loads. This makes it ideal for beams and columns in bridges. It is also combined with concrete for reinforcement to build strong structures. Mild steel for roofing in homes is an affordable choice.
Machinery
Mild steel is used to make vehicle parts like gears, shafts, and bearings. It’s easy to bend and shape, making it suitable for engine parts.
Industries
Mild steel pipes are used in industrial pipelines to carry oil and gas. This is because it can conduct heat well.
Electrical System
Mild steel is good at carrying electricity so it is used in making electrical wires and used in transmission towers, and transformers.
Fencing
Mild steel is cheap comparatively. We can see many farmlands using mild steel for fencing. It is thin and twisted but made into a fence. It offers high strength and protects the farm lands. It is ideal for residential and land boundaries also.
Magnetic Doors
Mild steel is magnetic in nature, so it is fitted in magnetic door closures for holding.
Appliances
Mild steel is used in many appliances, like refrigerators, washing machines, microwave ovens, and other electronics.
Grades of Mild Steel
There are different grades available for mild steel depending on composition, mechanical properties, and applications. IS 2062 is a standard mild steel in India and it has various grades. Two of them with properties and specifications are given below.
| Grade with Quality | IS 2062 E250 A (Plates) | IS 2062 E300 A (Plates) |
Composition (%) | Carbon – 0.23 (max)Manganese – 1.50 Sulphur – 0.045Phosphorus- 0.045Silicon – 0.40 | Carbon – 0.20 (max)Manganese- 1.50Sulphur- 0.045Phosphorus- 0.045Silicon- 0.40 |
Dimension | Width: 1000 – 3000mmThickness: 5-150 mmLength: 3000-18000 mm | Width: 1500-4020 mmThickness: 6-300 mmLength: 3000- 27000 mm |
Tensile Strength (MPa) | 410 | 440 |
Yield Strength (MPa) | 230 (Min) | 280 (Min) |
Elongation Percentage | 23 | 22 |
Application | This grade steel plates are used inSugar and paper industriesAerospace and nuclear plantsCement factoryBoilers and Heat exchangersAutomobilesInfrastructure | This grade steel plate is utilised inAutomobileMachine buildingGeneral engineeringFabricationHeavy infrastructural projects |
Difference Between Mild Steel and Stainless Steel
| Characteristics | Mild Steel | Stainless Steel |
| Composition | Carbon is the key alloying element (0.05-0.25 %) | Chromium is the key alloying element (at least 10.5 %) |
| Strength | Provides high strength for everyday applications. | Higher in strength compared to mild steel and more durable. |
| Corrosion Resistance | Low corrosion resistance | High corrosion resistance |
| Cost | Low in cost | More expensive than mild steel |
| Magnetic Property | Attracted to magnets | Not all grades are magnetic |
| Weldability | Easy to cut and join | Difficult in welding and needs specialised techniques |
| Thermal Conductivity | High in thermal conductivity | Lower than mild steel |
| Application | Construction, machinery, roofing and fencing | Medical equipment, food processing, kitchen utensils and aerospace |
| Appearance | Rough and uneven surface | Smooth and glossy appearance |
Advantages of Mild Steel
- Mild steel can bend, shape, and twist easily due to its low carbon content. This makes it perfect for creating intricate and complex designs. Its soft nature allows it to stretch extensively without breaking.
- For easy metal fabrication, a low melting point is essential. Mild steel has this property, making welding simple and preventing the overheating or burning of the metal.
- Although mild steel is less expensive than other steel types, it doesn’t compromise on strength. Made from readily available resources and fewer alloying elements, mild steel remains cost-effective.
- Mild steel is highly recyclable, so it can be reused multiple times without losing its properties.
Disadvantages of Mild Steel
- The major issue of mild steel is it is vulnerable to corrosion. It is easily affected when it comes into contact with moisture or water. It needs special coatings to prevent corrosion, but that provides only minimal protection.
- Mild steel has low heat resistance. It cannot be used for high-temperature applications and starts to lose strength and warp in those conditions.
- Mild steel has relatively low tensile strength, so it becomes unfit for heavy load-carrying structures.
Conclusion
Mild Steel plays an incredible role in the development of infrastructure, industries, and aerospace. Its adaptability and strength make it renowned for various uses. Though there are many grades available, it is always best to choose the grade which is suitable for your project.
FAQs
Mild steel differs from other steel types by having low carbon content. It is less strong but more ductile and easier to weld when compared to other steel types.
No, mild steel can be easily scratched and damaged.
Mild Steel is stronger and cheap, but stainless steel is more durable and resists corrosion better.