Stainless Steel vs Aluminum: 12 Major Differences between Stainless Steel and Aluminum

Aluminum and Stainless steel are two widely used materials in various industries. Wherever lightweight is a requirement, aluminum seems to be a good metallic option. Stainless steel is widely used as a corrosion-resistant ferrous metallic alloy. In this article, we will explore 12 major differences between stainless steel and aluminum.

1. Stainless Steel vs Aluminum: Appearance

Stainless steel is shiny whereas aluminum usually has a dull texture. However, weather can change appearances. Still, stainless steel will be brighter as compared to aluminum.

2. Stainless steel vs Aluminum: Composition

Aluminum is non-ferrous metal whereas stainless steel is ferrous where iron is the main constituent element. Pure aluminum is metal but stainless steel is an alloy.

3. Stainless Steel vs Aluminum: Strength to Weight Ratio

Even though stainless steel is stronger than aluminum because of its almost one-third weight It is one of the preferred materials in the automobile and aircraft industries. Aluminum has approximately half the strength compared to stainless steel. So, the strength-to-weight ratio of aluminum is better than stainless steel and this aspect makes aluminum a better choice in various industries.

4. Aluminum vs Stainless Steel: Corrosion Potential

In a normal environment, aluminum has very good corrosion resistance and does not rust. However, in some extremely acidic and base environments, it corrodes rapidly and can even result in catastrophic failure.

Stainless steel is an alloy of iron, chromium, nickel, manganese, and copper. The chromium is purposely added to generate a protective film and provide corrosion resistance. Also, as stainless steel is non-porous, it increases its corrosion resistance further.

5. Stainless Steel vs Aluminum: Thermal and Electrical Conductivity

When comparing both metals in terms of thermal conductivity, aluminum is better as compared to stainless steel. Because of this reason, aluminum is used widely for air conditioners and car radiators. However, stainless steel has high thermal resistance as compared to aluminum and thus can be used at high temperatures.

Aluminum has better electrical conductivity as compared to stainless steel.

6. Aluminum vs Stainless Steel: Cost

When comparing in terms of weight, Aluminum usually is costlier than stainless steel. However, when compared in terms of volume, due to low density, Stainless steel is costlier than aluminum.

Also, the aluminum refining process is less complex than producing stainless steel. This also reduces the cost of aluminum.

7. Stainless Steel vs Aluminum: Workability

Aluminum being soft is very easy to cut and form. On the other hand, Stainless steel is very difficult to form. For producing any customized shape, aluminum will take less energy and time as compared to stainless steel.

8. Aluminum vs Stainless Steel: Welding property

Aluminum is difficult to weld as compared to stainless steel. So, for applications involving an extensive amount of welding, stainless steel will be a better choice as compared to aluminum.

9. Aluminum vs Stainless Steel: Sparkability

While grinding stainless steel produces sparks whereas aluminum does not produce spark.

10. Aluminum vs Stainless Steel: Reactivity with food

Aluminum can affect the taste and color of certain foods. It is, therefore, stainless steel is preferred over aluminum in the food industry as stainless steel is non-reactive to foods.

11. Stainless Steel vs Aluminum: Occurrence

Aluminum is naturally available from bauxite ores. On the other hand, stainless steel is a fully man-made engineered alloy. Stainless steel is not naturally available.

12. Aluminum vs Stainless Steel: Magnetic Properties

Aluminum does not show magnetic properties but certain grades of stainless steel have magnetic properties.

The major differences between stainless steel and aluminum can be summarized below:

Aspect	Stainless Steel	Aluminum
Composition	Primarily iron, with chromium (≥10.5%) and nickel	Primarily aluminum, often with copper, manganese, silicon, or magnesium
Density	High (around 8,000 kg/m³ or 8 g/cm³)	Low (about 2,700 kg/m³ or 2.7 g/cm³)
Strength-to-Weight Ratio	Lower than aluminum but high in absolute terms	Higher due to lower density, ideal for weight-sensitive applications
Corrosion Resistance	Excellent, especially with high chromium content	Good, but susceptible to galvanic corrosion when in contact with other metals
Conductivity	Lower thermal and electrical conductivity	High thermal and electrical conductivity
Thermal Expansion	Lower thermal expansion coefficient	Higher thermal expansion coefficient
Magnetic Properties	Can be magnetic (ferritic and martensitic types)	Non-magnetic
Machinability	More difficult to machine due to the hardness	Easier to machine
Formability	Moderate to good, depending on the grade	Excellent, easily formed into shapes
Weight	Heavy	Light
Durability	Extremely durable and wear-resistant	Durable, but softer and can dent or scratch easily
Surface Finish	Can have a high-quality, shiny finish	Typically has a matte or anodized finish
Recyclability	Highly recyclable	Highly recyclable
Cost	Generally more expensive	Generally less expensive
Common Uses	Kitchenware, medical devices, automotive parts, construction materials	Aerospace components, beverage cans, automotive parts, electronics
Environmental Resistance	Better suited for harsh environments and high temperatures	Better for applications requiring lightweight materials
Weldability	Generally good, especially with appropriate filler materials	Excellent, often used in structures that require extensive welding
Maintenance	Low maintenance, does not require coating	May require protective coatings or anodization for enhanced durability
Tensile Strength	Generally higher (around 400-500 MPa for austenitic grades)	Lower (typically around 90-130 MPa for commercial grades)

Conclusion

Even though both aluminum and stainless have varying properties, both of them are highly useful materials. The selection between aluminum and stainless steel mainly depends on the application. So, the end-use dictates which material to be used for a specific application.