Steel tubes and pipes are found in automotive, aeronautics, industrial, architectural and medical applications. Aluminium and stainless steel materials are most commonly used, each with its own unique characteristics that make the material a great choice for different industries. When you have determined that you need either piping or tubing then you will want to select the best metal.
How to Select the Right Metal
If you are looking for a new tubing material, it can seem like there are so many options. Both stainless steel and aluminum pipe and tube comes in various alloys with different mechanical and physical characteristics. Every metal has properties that are common to all of its alloys.
Mechanical Property
When choosing the right material for your application, you should consider its mechanical properties. If strength is more critical, you might choose stainless steel due to its high strength/weight ratio and ability of cold-working. If your goal is to keep components lightweight, then aluminum may be a more suitable choice. Aluminum weighs one third less than a similar-sized stainless steel component.
Corrosion resistant
You should also consider the heat resistance or corrosion resistance of the metal tubing. The corrosion resistance of stainless steels and aluminum will vary depending on which alloy is chosen. Both stainless steel and aluminum are protected against corrosion by passivating oxides that form at the metal's surface.
Heat Resistance
Passivation can have a negative effect on electrical conductivity. Due to their poor electrical conductivity, stainless is not a popular material. Aluminum's conductivity is high, and it has a thermal conductivity which is three-times greater than steel. This makes aluminum a good choice for power lines. If you are looking for a material that can move electricity or heat, aluminum is likely to be the best choice.
It doesn't matter whether you are using your tube to intentionally conduct heat or not, as long as it can withstand temperatures in the environment where it will be operating. The stainless steels with a high concentration of chromium or nickel will retain their strength in high temperatures. Aluminum's strength increases when the temperature drops. It is also tougher at low temperatures than many other steels.
Is Stainless Steel Aluminum?
In summary, mechanical properties are important to consider, along with corrosion resistance and heat resistance. Once you choose the type of metal that's best for your application you can select the exact alloy you require.
Stainless Steel 201
The wide range of iron carbon chrome alloys included in this term will allow you to choose the best grade for any application. T304 and T316 grades are the two most common grades for steel pipes and tubes. They are both part of 300 series alloys which contain nickel along with chromium.
T304 is known as the classic stainless-steel alloy. It also contains 18% nickel and 8% chromium. T316 is a well-known alloy that's used in many applications, including food service, medical equipment and other industrial uses.
The properties of an alloy are greatly affected by the heat-treatment process and its history in cold working. Ask a metallurgist for help in determining the properties or attributes of your tubing. They can also guide you on the combination of alloys and processing that will work best for your specific application.
Tubing specialists also offer advice on the sizes of tubes and fabrication processes. Stainless steel tubing is available from 1/16 to eight inches in fractional and metric ODs. As small as 0.008" for tubing. Hypodermic applications. Fabrication methods include cutting, welding, bending, coiling, and end forming.
If you are using stainless steel in your application and you think it will outlive its usefulness, you should start thinking about what you want to do with the tubing. Although the alloying materials that are used to make stainless steel makes it difficult for recycling, be assured that approximately 50% of all new steel scrap is recycled into stainless.
Aluminum ABCs
The most commonly used alloys of aluminum for tubing are 2024 and 3003, followed by 5052, 6001, 7075. Alloys with copper, zinc, magnesium, manganese, and silicon as their primary alloying element have slightly different physical characteristics.
Engineers use alloys 2024 6061 7075 in aircraft structures for their high strength/weight and good fatigue resistant. Untreated 2024 or 7075 is susceptible to corrosion. 6061, however, is naturally corrosion resistant and easy to work with. 7075 offers greater strength at lower weight, but it costs more.
Alloy 3003 is best for applications which require corrosion resistance with high strength but not as much on ductility. Highly weldable alloy 5052 can be used for applications requiring many joints.
Just as with steel composition does not tell the full story. The exact properties a given alloy of aluminum depend also on its tempering or heat-treatment. Temper O means the alloy will be used as annealed. It is at its most ductile and least strong. Heat treatments are used for temperers that start with "T," such as T3,T4,andT6. The metal is then strengthened by cold working, or aging.
Specifying the size, temper and other fabrication operations will follow after you've selected the correct aluminum alloy. Aluminum tubing has an OD that typically ranges from 0.062 inch. Aluminum tubing is available in ODs ranging from 0.062 inch. Wall thicknesses start at 0.010 inch. To 0.250 in. Aluminum tube suppliers will cut, bend, flare and fabricate tubes according to requirements. Your aluminum tubing will have a long lifespan, and you can recycle it as it is 99.8% pure Aluminum alloy.
Still Got Questions about Aluminum vs Stainless Steel Pipe & Tubes?
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