You can find mild steel and aluminum everywhere, from households to large industries. Each has unique properties and features. However, when choosing between these metals, a debate arises about mild steel vs aluminum. Some prefer mild steel for its robustness, while others prefer aluminum for its lightweight.
However, what truly sets these two metals apart, and which suits your project? The answer to this question lies in their difference. Whether you are working on a DIY project or a skillful engineer, knowing the differences is crucial for desired outcomes. I will explore the key differences between aluminum and mild steel in this article. So, let’s get started!
Overview of Mild Steel and Aluminum
Mild steel is a low-carbon steel containing 0.05% to 0.25% carbon. Its composition also includes a small amount of iron, silicon, and manganese. However, it lacks chromium and nickel. On the flip side, aluminum is a silvery white metal extracted from bauxite ore. It can be alloyed with other metals to obtain the desired metal.
The main factor that sets these two metals apart is their different composition. For example, mild steel’s low carbon content makes it easier to cut and shape. Carbon also provides high tensile strength and makes it less ductile. The iron in mild steel has magnetic properties, which is helpful for many applications.
Conversely, aluminum does not involve any other metal in its composition. Thus, it slightly compromises some properties, such as being less strong. However, mixing it with other metals, such as copper and silicon, can obtain the desired features. These elements provide added strength and durability.
Mild Steel vs Aluminum: Primary Differences
Both mild steel and aluminum are power players in the world of metals. So, it becomes confusing for anyone to choose the right metals between these two. However, apparent differences can make the decision easy. So, let’s dive in and explore the primary distinction between mild steel and aluminum.
1- Strength and Hardness
Strength indicates how a metal can withstand heavy forces. However, hardness shows the ability of any material to resist dents and scratches. Both mild steel and aluminum differ in this regard. For example, mild steel is more rigid and stronger. WHY? The reason lies in its alloy nature. As I said above, it contains low carbon and iron content.
These two metals add strength and hardness. Moreover, hardness makes mild steel less prone to dents and scratches. On the other hand, aluminum is a soft material. Even if you make its alloy with other metals, it does not meet the strength of mild steel. This delicate nature of aluminum makes it more prone to dents and scratches.
2- Weight and Density
The mass of material per unit volume is called density. In simple words, density indicates how much a material is heavy. If we talk about the density of aluminum, it is less, which is about 2.7 g/cm³. This low density shows that aluminum is a lightweight metal. The reason lies in the atomic structure, which contains loosely packed atoms.
Conversely, mild steel has a 7.85 g/cm³ density, almost three times higher than aluminum. The higher density directly makes it heavy and solid metal. Again, the reason for this is the tight arrangement of atomic particles. Iron is the main factor enhancing the density of mild steel.
3- Corrosion Resistance
Corrosion resistance is another factor that sets mild steel and aluminum apart. In this term, aluminum is a clear winner. WHY? Aluminum forms an oxide layer naturally when exposed to oxygen or rust. This layer acts as a protective shield and saves the surface from further corrosion. Thus, aluminum is ideal for outdoor moist and rusty areas.
On the opposite side, mild steel is highly compromised in corrosion resistance. The first reason is the presence of iron. Iron, when exposed to water or oxygen, forms an iron oxide, which is commonly called rust. This rust gradually spreads and weakens the surface. Moreover, the absence of chromium also enhances the chances of corrosion.
4- Weldability and Machinability
Weldability refers to connecting metal joints, while machinability shows how easily a metal can be cut and shaped. Weldability depends heavily on the melting point. Mild steel has a melting point of about 1,370 °C, which is higher than aluminum( ~660°C). This means mild steel is easy to weld as it does not melt quickly during welding.
However, aluminum has a higher chance of melting, which creates difficulty. So, special techniques such as TIG (Tungsten Inert Gas) are used to weld aluminum. Moreover, aluminum also creates an oxide layer on heating, which makes welding difficult. If we look at machinability, mild steel is harder to cut and shape.
The reason is in its hardness and strength. Special tools are required during its milling operations. On the inverse side, aluminum offers ease in machinability. It is lightweight and soft and does not require heavy and specialized tools. Lastly, chip management during the milling of aluminum is also easier than that of mild steel.
5- Electrical and Thermal Conductivity
Electrical and thermal conductivity determines how easily a metal can conduct current and heat. Both mild steel and aluminum behave differently in this regard. For instance, mild steel is a poor conductor of heat and current. It has about 50 W/m·K thermal conductivity and 3-15% electrical conductivity, which is very low. So, mild steel is commonly listed as an insulator.
The reason is that electrons in mild steel are tightly closed to each other. These electrons do not allow the flow of heat and current. On the flip side, aluminum is a good conductor of heat and electricity. For example, its thermal conductivity is about 205 W/m·K, and its electrical conductivity is 61%. The atoms in aluminum are loose, which quickly transfers heat and current.
6- Environmental Impact and Recycling
Environmental sustainability should be your primary concern while handling any material. Let’s discuss how mild steel and aluminum contribute to sustaining the environment. Basically, mild steel is more eco-friendly because it requires less energy to extract from ore. Moreover, the initial production process also uses less energy.
On the flip side, aluminum is comparatively less energy-efficient. Extraction of aluminum from bauxite ore requires special mining techniques. Moreover, the initial production process requires 4 to 5 times more energy, which affects our environment. However, in terms of recycling, aluminum is convenient.
The aluminum recycling process is easy and saves 95% of energy. In simple words, recycling aluminum is more efficient than producing new aluminum. Additionally, aluminum does not lose its structural integrity after recycling. However, due to complications, recycling mild steel saves just 60-74% of energy. Moreover, it loses its strength slightly after recycling.
7- Applications
Due to variations in many terms, both metals perform different duties in different fields. The typical applications of mild steel involve the following:
- Construction and Infrastructure: Mild steel makes beams, columns, and bridges.
- Automotive Industry: It makes car chassis and frames, and body panels.
- Manufacturing and Machinery: Used to make machine gears, boilers, and turbines.
- Household and Domestic: You can use mild steel to make doors, windows, and kitchen appliances.
Now, take a glimpse at the applications of aluminum:
- Aerospace and Aviation Industry: lightweight aluminum is a big plus for aerospace industries. It is used to make the wings of aircraft and drones.
- Food and Beverage Packaging: Aluminum keeps the food fresh for a long time. So, it is used in packing food. Moreover, aluminum is also used to form lids due to its lightweight.
- Electronics and Electrical Industry: Aluminum has higher electrical and thermal conductivity. Thus, it is used in making wiring and electrical vehicles.
- Medical and Healthcare Industry: Aluminum is a non-toxic metal. It has a non-porous surface, so it makes surgical instruments such as syringes.
8- Cost and Affordability
Cost is the main differentiating factor between mild steel and aluminum. In terms of cost, mild steel is an affordable option. WHY? Its readily available iron, silicon, and carbon elements are the main reason. These materials are on the earth’s crust, so their mining costs less. Moreover, the production process of mild steel is also effortless.
Lastly, the recycling of mild steel further reduces overall costs. On the other hand, aluminum is not readily available on the Earth’s crust. Mining requires higher energy, which increases the price. Lastly, the manufacturing process of aluminum involves intensive heat and special techniques. However, aluminum is cost-effective as long as it does not require maintenance.
Key Factors to Consider When Choosing Between Mild Steel and Aluminium
Are you stuck between mild steel and aluminum and can’t decide which suits you better? Worry not! In this section, I will share some key considerations to help you make an informed decision. Let’s jump right in!
- First, consider the strength and hardness of each metal. If your project requires durability, you should choose mild steel. However, if lightweight is your preference, go for aluminum.
- The second and most crucial factor is corrosion resistance. As I said above, aluminum is more corrosion-resistant due to the formation of oxide layers. So, I recommend using aluminum for outdoor uses. However, you can use mild steel for less moist, dry, and indoor applications.
- Mild steel is more straightforward to machine and fabricate. So, if you own simple machines, you should choose mild steel. However, aluminum requires special techniques and tools. So, for complex geometry projects, you should prefer aluminum.
- Lastly, keep the cost of both metals in mind. Aluminum can hit your budget harder with its higher prices. But it is cost-friendly in the long term. The reason is that it does not require continuous maintenance. But if you prefer less initial cost and overall lower prices, go for mild steel.
Conclusion
Mild steel and aluminum are two types of metals. Both have unique strengths and weaknesses. I have discussed the key differences between mild steel and aluminum in this article. For example, mild steel is harder and stronger due to its higher carbon content. Moreover, it has a higher density and more weight. Lastly, mild steel has less corrosion resistance due to the presence of iron.
So it is best for indoor and dry areas. On the flip side, aluminum is a lightweight metal. It is less hard but contains higher thermal and electrical conductance. Lastly, the complicated manufacturing process of aluminum makes it more expensive. So, first, you understand your project’s demand and decide between mild steel and aluminum.