Aluminium and Stainless steel may look pretty similar, but they have vast differences. 

1. Introduction

Stainless steel and aluminium are popular metal fabrications after carbon steel. They are widely used for their versatility and corrosion resistance, however they have many dissimilarities. To determine when it is better to use each of them, a comparison on various factors like their compositions, mechanical properties, and cost should be conducted.

2. Comparison of Stainless Steel and Aluminium

• Cost

Aluminium is known to be less expensive than stainless steel; however, due to fluctuations in the commodity prices this statement might be untrue. Price comparison should be re-checked at the time of the purchase.

• Weight

Aluminium’s lightweight characteristics make it perfect for use weight sensitive applications. However, aluminium has a lower structural resilience e.g., yield and tension strengths. For applications where strength to ratio is critical, alloys of each material should be calculated to determine the right option.

• Surface Finish and Coating

Aluminium can have various coatings such as wet paint, powder coating and anodizing which are not suitable for stainless steel.

• Welding

Stainless is relatively easy to weld compared to aluminium. Besides, some aluminium alloys are not weldable.

• Thermal Characteristics

Aluminium offers better thermal conductivity than stainless steel. One of the other hand Stainless Steel can be used at much higher temperatures than aluminium which will start deformation over 400 degrees.

• Mechanical Processing

Aluminium is quite soft and easier to cut and bend. Due to its resistance to abrasion, stainless steel can be difficult to work with. Aluminium’s low melting point makes grinding very difficult. Stainless steels are harder material and they are prone to heat better than aluminium.

• Conductivity

Stainless steel is a poor conductor compared to aluminium alloys. Aluminium offers better both thermal and electrical conductivity.

• Corrosion Resistance

Incomparable to carbon steel, both aluminium and stainless steel have good corrosion resistant, however, stainless steel has overall superiority in terms of corrosion resistance compared to aluminium due to its chromium content. For handling aggressive corrosion risks, such as using highly acidic or basic substances or in marine environments, stainless steel offers stronger corrosion resistance.

Aluminium contains no iron, so it cannot rust, but it does corrode. Aluminium also has a thin layer of aluminium oxide that protects it from rusting but this layer doesn’t protect it from other forms of corrosion.

Anodizing coating of aluminium can also increase corrosion resistance at a cost. But this requires a delicate maintenance to sustain this thin layer.

3. Conclusion

When comparing stainless steel and aluminium, it becomes obvious that they both possess characteristics that make them popular certain applications. The outstanding corrosion resistance, easy maintenance, and high strength of stainless steel make it an ideal choice in a vast range of situations. On the other hand, when it comes to thermal and electrical conductivity and weight concerns, aluminium exhibits better performance. Last but not least, characteristics of different alloys and grades of both metals might deduce exceptions to the above statements.

We also recommend our two articles; aluminium fabrication and stainless steel fabrication to understand the difference between these two popular metals.