Aluminium and stainless steel are two of the most widely used metals, as their versatility and properties make them staples in the manufacturing industry. But, there is a difference between aluminium and stainless steel. A few differences, in fact.
Here are the main differences to look at when comparing stainless steel vs. aluminium—including when to use each and the answer to the commonly asked question: which is better, aluminium or stainless steel?
8 differences between aluminium and stainless steel
Aluminium and stainless steel may look similar but have some fundamental differences. Here are eight of the most significant differences between the two metals.
While both are strong metals, stainless steel is much stronger than aluminium. However, that strength also makes stainless steel much heavier, meaning aluminium actually has a higher strength-to-weight ratio. So if you need a strong and lightweight metal, aluminium is probably your best bet.
As mentioned, aluminium is lighter than stainless steel and is actually almost one-third of the weight of stainless steel. Aluminium’s lightweight properties make it perfect for use in aeroplanes and skyscrapers.
Aluminium alloys can be developed to be stronger than pure aluminium and can support heavier weights.
3. Conductivity: electrical and thermal
Stainless steel is a poor conductor of electricity compared to other metals due to its dense protective oxide layer. It is also a poor thermal conductor. However, stainless steel can be used at much higher temperatures than aluminium, which softens at higher temperatures.
Aluminium is an excellent electrical and thermal conductor. Because of this, you’ll often see aluminium used in car radiators, air conditioning units and high-voltage power lines.
4. Melting point
The melting point of a metal helps determine its formability. The melting point is the temperature at which a material transforms from a solid state to a liquid state.
Stainless steel has a higher melting point, ranging from 1230 °C to about 1530 °C (2250 – 2790 °F), compared to aluminium, with a melting point of 660.37 °C (1220.7 °F). This means that stainless steel is better for heat resistance applications than aluminium.
5. Corrosion resistance
Aluminium and stainless steel both exhibit excellent corrosion-resistant properties. However, stainless steel is more corrosion-resistant than aluminium because of its elemental composition of iron, chromium, nickel, manganese and copper. It is also non-porous, making it more resistant to corrosion.
While aluminium doesn’t rust, it can corrode when exposed to extreme acidic or base environments.
Commercial quality aluminium and stainless steel are typically similar in price per kilogram. However, since aluminium is lighter, it usually makes a more cost-effective metal. Stainless steel is usually about 30% more expensive than aluminium due to the weight difference.
If material cost is an essential criterion for your project, aluminium will be the more affordable metal.
7. Workability and welding
Aluminium is easier to work with as it is relatively soft and easy to cut, stretch and manipulate. Due to its resistance to wear and abrasion, stainless steel can be more challenging to work with.
Stainless steel, meanwhile, is relatively easy and cost-effective to weld, while aluminium can be more difficult. On the other hand, aluminium is resistant to corrosion and lighter in weight, while stainless steel is 2.5 times heavier and much more robust than aluminium—all factors that influence welding.
Aluminium and stainless steel are both durable materials. However, if you need to choose between stainless steel or aluminium and durability is a major factor, stainless steel is a better option due to its strength and hardness.
When to use stainless steel vs. aluminium
Stainless steel and aluminium are used everywhere. It’s almost impossible not to come into contact with at least one of the metals each day. Both metals are found in cars, kitchens, bridges, aircraft, building constructions, and many more.
Here are a few common-use applications of both stainless steel and aluminium.
Application of stainless steel
You’ll find stainless steel used in the automotive industry, culinary industry, architecture and more.
Here are a few examples of when to use stainless steel:
- The architecture of bridges, sculptures, monuments, buildings
- Surgical tools like forceps, scissors and surgical implants
- Automobile mobile bodies, rail cars and engines
- Culinary equipment like kitchen sinks, cutlery and food prep tables
- Plumbing, bine treatment, wastewater treatment and desalination
- Chemical and petrochemical processing
Application of aluminium
Aluminium is used in various industries due to its excellent corrosion resistance. You’ll find aluminium applications in the transportation industry, electrical industry, architecture and household appliances.
Here are a few examples of when to use aluminium:
- Household appliances like dishwashers, dryers, refrigerators and dryers
- The transportation industry, including automotive, train rails, aeroplanes, trucks, marine vessels, bicycles and spaceships
- Long-distance power lines, transformers, motors, generators and conductor alloys
- Window frames, roofing, doors, sheathing and building wire
- Packaging, including cans and foils
Which is better: aluminium or stainless steel?
Both metals have good properties that are beneficial for different uses. So, deciding on aluminium or stainless steel depends on what you want to use it for.
The main advantages of each:
- Aluminium is lightweight and has high ductility, good conductivity and malleability.
- Stainless steel has high tensile strength, is heat resistant, very durable and low maintenance.
Understanding the differences between the metals helps you to know when to use aluminium vs. stainless steel. For example, because it is conductive and lightweight—unlike stainless steel—aluminium is used for electrical applications. But, stainless steel is a better option for engines and processing equipment as it is strong and resistant to heat and corrosion.
It’s also important to consider each metal’s environmental impact. Stainless steel is the most recycled material globally, while aluminium is the most recyclable material. Both metals can therefore be used over and over again.