Industry Articles From Kaempf and Harris

How Do Aluminum And Stainless Steel Differ?


Aluminum and stainless steel have a variety of individual applications in sheet metal projects. However, the latter is an alloy while aluminum is a natural element.

What are a few other differences between the two common sheet metal fab shop metals? Kaempf & Harris of Frederick, Maryland, offers some answers:
    1. Strength and Weight. Aluminum sheet metal is typically not as strong as steel, which can be recycled without the loss of strength. However, aluminum is almost one third of the weight of steel. This is the main reason why aircraft and bodies of automobiles are made from aluminum -- it is lighter.

      In fact, stainless steel is so heavy and strong that it is less likely to warp, deform, and bend under any weight, force, or heat.
    2. Composition. Like we mentioned before, stainless steel is an alloy made up of iron, nickel, manganese, copper, and between 10 to 30 percent chromium oxide (an inorganic compound added to provide extra corrosion and rust resistance). Because it is non-porous the resistance to corrosion is increased.

      Aluminum, a natural element, also has high oxidation and corrosion resistance due to its passivation layer (a natural technique that allows a material to be less affected by the environment).

      When aluminum is oxidized, its surface will turn white and sometimes pit. In extremely acidic or basic environments, aluminum may corrode rapidly with catastrophic results.
    3. Thermal Conductivity. Aluminum has a much better thermal conductivity than stainless steel, which is one of the main reasons it is used for car radiators and air conditioning units.

      However, stainless steel can be used at much higher temperatures than aluminium, which can become soft at any temperature above 400 degrees Fahrenheit.
    4. Cost. The steel industry has an estimated $900 billion turnover, making it the second largest industry in the world after oil and gas. This is because of global demand, fuel costs, price and availability of iron and bauxite ore, and the process of spinning.

      Aluminum sheet metal takes less time and effort to refine, making it less expensive to purchase raw and process.
    5. Malleability. Aluminum sheet metal is more malleable and elastic, making it easier to cut and form. This quality makes it great for projects like cooking pots and pans and tools.

      Fun fact: Stainless steel is less reactive with foods, whereas aluminum can affect a food’s color and flavor, but most canned goods are made with aluminum.

      Stainless steel can be more difficult to work with due to its resistance to abrasion and forming, which means it is ideal for heftier projects like roofing, major appliances, computers, skyscrapers, and bridges.
    6. Conductivity. Stainless steel is a poor conductor compared to most other metals. Because aluminum sheet metal is a very good conductor of electricity, high-voltage overhead power lines are generally made of aluminum.
    7. Spark-ability. If you would like to tell the immediate difference between the two hard metals, subject each to a grinder. Stainless steel will give off sparks, while aluminum will not.
    8. Market. China produces the most aluminum in the world annually, followed by Russia and Canada. China also produces the most steel globally. However, this trend is followed by Japan and India. Learn more in Who Absolutely Dominates The World In Steel Production?

While each material has a specific job in a sheet metal fabrication shop and can withstand only certain techniques, both aluminum and stainless steel are important metals.

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