Stainless Steel vs Aluminum: What is the Difference Between

Aluminum and stainless steel are playing vital role in different aspects of life including food storage, automotives, aerospace and home decor purposes. Aluminum was discovered in 1825, and industrial production was started in 1856. On the other hand, stainless steel was invented by Harry Brearley in 1913 and further developments in the field of stainless steel has continued till date. Aluminum and stainless steels are long lasting due to corrosion resistance property and recyclable. Initially, production of aluminum has faced difficulties but still the production was increased from 200 tons to 2 million tons from 1885 to 1998. This article will provide a comparison between stainless steel and aluminum by development a solid ground for each alloy.

Stainless Steel Composition and Properties

The purpose of enlisting the different types of stainless steels in a table, is to get an idea about the variation of alloying elements in different types.

Table 1. Chemical composition of different types of stainless-steel alloy

*Balanced by Fe

Aluminum Composition and Properties

Cast and wrought, both alloys of aluminum ae famous. This article will discuss wrought aluminum alloys which are divided into different series base on their main alloying elements. Main alloying elements and their properties are listed in the following table.

What is the Difference Between Aluminum and Stainless Steel

Aluminum alloys are also famous due to high strength to weight ratio. Stainless steel is mainly composed of chromium and Fe along with other alloying elements such as Mo, Ni, Si etc.

Heat resistant

Stainless steel has melting point of 2500 ⁰F and aluminum has 1200 ⁰F. Heat resistance property of stainless steel is better than aluminum. As aluminum is good conductor of heat and found its applications in heat exchangers and heat sinks due heat conducting and dissipating property.

How much lighter is aluminum than steel

Density of the stainless steel and aluminum is 7.8 g/cm³ and 2.7g/cm³, respectively. Aluminum is 2.9 times less dense than stainless steel. Weight of the aluminum is lower than stainless steel.

Weight difference between steel and aluminum

If aluminum and stainless steel are taken in same volume, then stainless steel will be 1/3 times heavier than aluminum.

Aluminum vs stainless steel corrosion

Aluminum and stainless steel doesn’t rust. In stainless steel 10-11 wt.% chromium is added, for corrosion resistance. As a result of oxidation from the surface Cr₂O₃ forms on the surface and protect it from excessive and further oxidation. Alumina (aluminum oxide, Al₂O₃) is form on the surface of aluminum or its alloy to protect it from corrosion. In comparison with stainless steel, protective layer of aluminum is not very effective and efficient in harsh environment.

Aluminum vs stainless steel in saltwater

Aluminum forms protective layer but that is not as effective as passive layer of stainless steel. Aluminum doesn’t exhibit good corrosion resistance against marine environment. Pitting or localized corrosion is a problem for aluminum in the presence of halide ions.

Is stainless steel stronger than aluminum

Yes, ultimate tensile strength of stainless steel is superior than aluminum. Tensile strength of aluminum alloy is found in the range of 90 to 690 MPa [8]. Maximum tensile strength of stainless steel is 1380 MPa. When high strength to weight ratio is required, aluminum is one of the best candidates. Well, aluminum perform well under low temperatures whereas stainless steel undergoes ductile to brittle transition.

Steel strength chart

Table 3. Ultimate tensile strength and yield strength of stainless steels [15].

Aluminum strength chart

Table 4. Ultimate tensile strength and yield strength of aluminum alloys.

Is stainless steel malleable?

Malleability of the material is a property where material undergo plastic deformation without getting cracked or fractured under compressive loading. Stainless steel is less malleable as compared to aluminum but possess some degree of malleability. Number of factors affect the malleability of steel which include temperature, alloying elements, compressive force and deformation rate. Metal fabrication process such as rolling, forging, stamping and bending of stainless steel is readily possible but with more specialized equipment’s as compared to aluminum. Austenitic stainless steel is comparatively more malleable than martensitic stainless steel.

Is stainless steel cheaper than aluminum?

No, stainless steel is not cheaper than aluminum. Alloying elements/constituents used in the production of stainless steel are expensive than the aluminum alloys. Alloy making/processing/machining/fabrication of aluminum is comparatively less expensive as compared to stainless steel.

Tensile strength of steel vs aluminum

Tensile strength of steel is as low as 450 and as high as 1240 MPa whereas tensile strength of aluminum lies in the range of 10-700 MPa. So, tensile strength offered by steels is comparatively higher than aluminum.

Steel vs aluminum color

Stainless steel has silver gray appearance and its surface can be made reflective as per requirement after polishing. Stainless steels are also found in copper and gold color as physical vapor deposition is implied for this purpose. Surface of the stainless steel can be as reflective as a mirror surface. Color of the aluminum is silver-white and different color of the aluminum surface can be achieved by anodizing and by applying paint.

Aluminum and stainless steel reaction

Aluminum and stainless steel undergone galvanic corrosion when come in contact with electrolyte. Aluminum is less noble metal than stainless steel as a result stainless steel acts as cathode and aluminum acts as anode. Aluminum will oxidize as a result aluminum ion and electron go into the electrolyte. Electron and ion’s reaction occur in electrolyte. Reduction reaction occur on stainless steel. Stainless steel remained intact and corrosion of aluminum gets accelerated when aluminum and stainless steel become in contact.

Applications

Dutch oven

Dutch ovens are made up of stainless steel as it is more capable of retaining heat as compared to aluminum. It is easy to clean and maintain but doesn’t have heavy and air tight lid. Cast iron is more appropriate choice between stainless steel and cast iron as it can retain heat for longer period of time in comparison with stainless steel. Aluminum has good heat conductivity than aluminum. Both materials exhibit good corrosion resistance.

Apple watch

Aluminum and stainless-steel apple watches are available in the market and aesthetically appealing. If light weight and comfortable is priority along with sleek designs, then aluminum apple watch is the right choice. Aluminum bands are available in different colors too. If luxurious look and wear and tear resistance is required than stainless steel is more appropriate choice. When it comes to affordability, aluminum apple watch is less expensive than stainless steel.

Cookware

Aluminum cookware get eroded or corroded when salty and acidic food is cooked in it and become a part of your food which is not healthy. Aluminum is a very good conductor of heat and could burn the food quickly too. On the other hand, stainless steel cookware has overcome all the problems offered by aluminum cookware. When it comes to affordability, aluminum cookware is less expensive.

Jewelry wholesale

Stainless steel is more durable as compared to aluminum. Yes, stainless steels can be used for jewelry and its longevity can be evaluated by the tensile strength of the stainless steel and protection given to it while using it.

Which is Better Aluminum or Stainless Steel

Aluminum is better than stainless steel or stainless steel is better aluminum, totally depends on the required properties of the application. Suppose light-weight but low strength is required along with the moderate or comparatively low corrosion resistance than stainless steel than aluminum would be an appropriate choice. If high strength and good corrosion resistance is required than steel would be better than aluminum.

Does aluminum alloy rust

No, aluminum alloy doesn’t rust under ordinary environmental conditions. In marine environment, halide ions have ability to cause rusting of aluminum by pitting or localized corrosion.

Is aluminum porous

Aluminum is not porous but alumina is. Alumina (Al₂O₃) is an aluminum oxide layer which act as a passivation layer to protect aluminum alloy from corrosion. Alumina can be porous and different techniques are used to reduce to porosity or block pores. Porous alumina is used in multiple applications such as catalyst, filtration and biomedical.

Best material for heat sink

Aluminum is a god conductor of heat whereas stainless steel is a good heat resistant. So aluminum is a better choice.

Is stainless steel or aluminum better for outdoors

Corrosion resistance and durable is required when material is supposed to used outdoor. Stainless steel is a better choice.

How to tell difference between stainless steel and aluminum

Stainless steel is silver or grayish color and aluminum is bluish gray color, if surface is not further possessed. Aluminum will be lighter in weight as compared to stainless steel for same volume of material.

Pros and cons of aluminum

1. High strength to wright ratio
2. Moderate corrosion resistance
3. Durable
4. Recyclable
5. High thermal conductivity
6. Poros protective layer
7. Bad corrosion resistance in marine environment
8. Good malleability

Pros and cons of stainless steel

1. Stainless steel is hygienic
2. Easy to maintain
3. High wear resistance
4. Good corrosion resistance
5. Aesthetically appealing and can be used in accessories.
6. High strength
7. Metal fabrication is tricky as more specialized equipment’s are required for metal fabrication. Bad malleability.
8. Heavy

Aluminum vs Stainless Steel：How to Choose in Machining and Welding Projects

Welding and machining of aluminum is comparatively easy. As aluminum has low melting point so multiple welding techniques are used to weld it which are Tungsten inert gas welding and metal inert gas welding. Chips of aluminum can easily fall off and avoid chip clogging during machining. On the other hand, welding of stainless steel is difficult due to high melting temperature and formation of chromium carbide (sensitization).

For the selection of most appropriate material as per demand or required properties, contact our experts to choose right for particular application.

FAQs 

Difference between aluminum and stainless steel apple watch

Aluminum apple watch is light weight, comfortable and affordable with sleek designs. Aluminum bands are available in different colors too. If luxurious look and wear and tear resistance is required than stainless steel is more appropriate choice.

Aluminum or stainless steel which is better for health

Oxide layer of stainless steel is not porous so materials won’t grow. Stainless steel cook wears, food processing equipment’s, food storage and surgical instruments are very famous. Stainless steel is better for health.