Rust compromises the mechanical characteristics of metal, alters the chemical properties, and is (usually) not considered aesthetically pleasing. It is for these reasons that many people in charge of design and material selection try to avoid having to deal with rust and the negative effects that come with it. One way to eliminate the threat of rust is to use metals that don’t rust.
Common metals that don’t rust include:
- Aluminum
- Stainless Steel (some grades)
- Galvanized Steel
- Red Metals (Copper, Brass & Bronze)
Aluminum
Aluminum cannot rust. This is because of the fact that rust is iron oxide, and most aluminum has virtually no iron in its composition. However, aluminum does oxidize, but it actually protects the underlying unoxidized aluminum. This is because the aluminum oxide is more corrosion resistant than the aluminum alloy it rests on. This is different than rust, because rust will flake away from an iron alloy thus allowing the rusting process to continue until material failure.
Stainless Steels
Stainless steel is another example of a metal that does not rust. Through it is important to note that some grades are more resistant to rust than others. Austenitic stainless steels such as 304 or 316 have high amounts of nickel and chromium. The chromium combines with the oxygen before the iron is able to which forms a chromium oxide layer. This layer is very corrosion resistant which prevents rust formation and protects the underlying metal. On the other hand, ferritic or martensitic stainless steels may be susceptible to rust because they contain less chromium.
Galvanized Steel
Galvanized steel is technically a coated material, but it is worth mentioning here. Galvanized steel is a carbon steel that would most likely rust if it did not have one or more layers of zinc applied to it. The zinc layer acts as a sacrificial metal for the steel. This means that the zinc layer will combine with the oxygen more readily than the iron in the steel will. This creates a zinc oxide layer that prevents the formation of iron oxide, thus eliminating the possibility of rust forming. However, if the zinc coating is damaged, or if the galvanized steel is placed in extreme environments, the zinc coating may be rendered ineffective and the steel will rust. Galvanized steel is also susceptible to “white rust” which is a type of corrosion that forms under specific conditions, typically involving water or condensation. The formation of white rust does not necessarily damage the material or the zinc coating.
Copper, Brass, and Bronze
Copper, brass, and bronze do not rust for the same reason as aluminum. All three have a negligible amount of iron in them. Therefore no iron oxide, or rust, can form. However, copper can form a blue-green patina on its surface when exposed to oxygen over time.
These Metals Don’t Rust But…
While these metals don’t rust, that does not mean that they do not corrode. They have their own forms of corrosion, such as pitting that can occur in stainless steel or the blue-green tarnish found on oxidized copper. Furthermore, if they are brought into contact with a carbon steel or other type of steel that does rust, iron deposits can be made on the surface of these materials that will oxidize and create rust.
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FAQs
Copper, brass, and bronze do not rust for the same reason as aluminum. All three have a negligible amount of iron in them. Therefore no iron oxide, or rust, can form. However, copper can form a blue-green patina on its surface when exposed to oxygen over time.
What type of metals do not corrode easily? ›
Gold and Platinum are the metals which do not corrode easily. Since they are unaffected by oxygen and other acids, they do not corrode visibly and are more stable than many of their compounds, such as oxides and sulphides. They were given the name noble metals because of their lack of chemical reactivity.
Which stainless steel never rusts? ›
Certain stainless-steel products contain high levels of chromium which can prevent the formation of rust. The alloy creates a thin chromium oxide layer on the surface to protect itself. 304 and 316 are the most common of our stainless steel options.
What is the strongest material that doesn't rust? ›
Platinum. Platinum is a pure metal that doesn't rust because it doesn't contain iron. Platinum doesn't rust, corrode, tarnish, or change color. It's dense, malleable, (moves easily) and at the same time, very strong.
What is the most corrosion resistant metal? ›
Corrosion-resistant metals can be a crucial part of any engineering project. The most popular solutions are stainless steel, aluminum alloy, nickel alloys, and copper alloys. However, iridium is the most corrosion-resistant metal known to man.
What metal is highly resistant to rusting? ›
Gold and platinum are highly resistant to corrosion. They are the least reactive metals and therefore, they do not react with air, water, acids, alkalis and other gases in the environment.
What is the cheapest metal that doesn't tarnish? ›
Jewelry-grade stainless steel, the affordable material of choice of all the experts we spoke with, is considered both tarnish-proof and water-resistant.
What is the best metal for outdoor use? ›
For typical projects such as a metal canopy, aluminum is the metal of choice. It survives well in the outdoors and is much more affordable and easy to work with than steel, brass, or copper. For outdoor decorations you may choose brass or copper, and for structural supports you may want to work with stainless steel.
What metal does not corrode outside? ›
To prevent oxidation and breakdown of metal products, such as handrails, tanks, appliances, roofing, or siding, you can choose metals that are “rust-proof” or, more accurately, “corrosion-proof.” Four basic types of metals fall into this category: Stainless steel. Aluminum metal. Copper, bronze, or brass.
What two metals do not get corrected? ›
Three metals which do not corrode are: Silver, Gold, and Platinum.
Gold, being the least reactive metal, will react with oxygen at a slower rate than sodium, potassium, and magnesium. Therefore, gold will undergo corrosion at a slower rate.
Which metal is best for not rusting? ›
Copper, brass, and bronze do not rust for the same reason as aluminium. All three have a negligible amount of iron in them. Therefore no iron oxide, or rust, can form. However, copper can form a blue-green patina on its surfaces when exposed to oxygen over time.
What steel does not rust or stain? ›
Stainless steel is a bit different. Though steel does contain iron, stainless steel also contains the element chromium, which is highly corrosion-resistant. Chromium protects the steel from rusting because chromium combines with oxygen before iron does.
What metal is waterproof? ›
It is chromium that makes stainless steel waterproof. So when you expose your stainless steel jewelry to water, chromium reacts with oxygen to form a hard, thin, and resistant oxide layer. This layer is so thin that it is practically invisible without the help of a transmission electron microscope.
Does titanium rust? ›
Pure titanium does not rust or tarnish like iron metals, allowing for prolonged exposure to water without the worry. In addition, titanium is even fully resistant against the corrosion effects of saltwater. This resistance is from a thin oxide film that covers the surface of pure titanium when exposed to oxygen.
