Corrosion-resistant metals are prized for their ability to resist degradation and deformation caused by corrosive materials and environments.
Consequently, they are widely used to manufacture items that must function in such environments.
Some metals that are not corrosion-resistant by nature can be made that way by the process of alloying, which gives them an added protective layer that prevents corrosion.
There are numerous factors for selecting a particular metal for a specific project (e.g., strength, aesthetics, formability, cost, etc.).
Nevertheless, for operating in highly-corrosive settings, metals that have an added degree of corrosion resistance are indispensable.
In the following sections, we will cover different types of corrosion, the main criteria for selecting anti-corrosion metals, the most common types of corrosion-resistant metals, and some very important ways of preventing corrosion.
This should give you enough understanding to select the right corrosion-resistant metals for your specific needs and requirements.
Corrosion is a process whereby metals are converted to an oxidized or stable form.
It is important to note that, although the terms are often used interchangeably, rust denotes a type of corrosion that happens only to metals that contain iron.
Corrosion is, on the other hand, is a wider term, denoting a process that affects all metals.
The process of corrosion itself is quite natural and usually occurs when oxygen, hydrogen, electricity, or dirt particles (bacteria) come into contact with metal.
Metal corrosion can also occur under extreme stress, causing cracks in the metal.
Learning about the different forms of corrosion and how they affect different metals is important since choosing the right metals for a specific corrosive environment will ultimately determine the overall success of the application the metal is used for.
If you choose the wrong metal, the following problems can occur:
Since corrosion shortens the lifecycle of metals, it also increases the cost of manufacturing and maintenance.
For instance, the cost of metal corrosion in the United States alone is around $276 billion per annum.
The following is a breakdown of the percentage of this cost by sector.
| Utilities | 34.70% |
| Transportation | 21.50% |
| Infrastructure | 16.40% |
| Government | 14.60% |
| Production and manufacturing | 12.80% |
To prevent these costs, you should be aware of different types of corrosion and how they affect your chosen materials.
There are nine different types of corrosion that can damage metals.
They include:
Once you’re aware of all of these types of corrosion, your next step will be to find the specific corrosion-resistant metal that can withstand them.
In other words, a material suitable for your desired application.
To assist you in the selection process, let’s go over the selection criteria for choosing the right corrosion-resistant metals.
Although managing corrosion involves many considerations, choosing the right metal for the job is the first step in securing the longevity of materials.
Nearly every metal has the potential to corrode, which makes choosing the right metals so vital for application integrity.
The most desirable properties to look for in corrosion-resistant metals include the following:
Another very important set of criteria for choosing the right corrosion-resistant metal concerns the level and procedures of quality control provided by your metal supplier.
Suppliers should sell alloys with specific corrosion-resistant elements that provide higher corrosion resistance than usual (e.g., high levels of nickel and chromium).
To ensure that the product has the desired features, manufacturers should also have a thorough control and inspection process in place before, during, and after manufacturing.
That will mitigate any imperfections that may hamper performance.
A supplier with a high level of material expertise in dealing with metals, such as Bunty, is preferable. Such a supplier will better be able to assist in the selection process.
Also, metal suppliers should offer metals with the appropriate mechanical properties and compatibility for what you need them to do. These characteristics include tensile strength, yield strength, and ductility.
Suppliers that have an established track record of matching the right metals with the client’s desired purpose will provide the best longevity, system compatibility, performance, and safety.
Finally, ongoing support after purchase is vital, as it will increase longevity and lower the cost of material investments.
In summary, to increase the chances of getting the most accurate corrosion-resistant metal for your project, be sure to identify the type of corrosion the items you’re using are most susceptible to.
Then, select the metal that can withstand your specific circumstances, and find an expert supplier that provides the quality controls mentioned above.
Businesses looking to protect their products and equipment from the harmful effects of factors like salts, acids, and UV (ultraviolet) exposure should consider manufacturing them with the top anti-corrosive metals.
Let’s look at the four types of the most corrosion-resistant metals.
The most common and perhaps most popular corrosion-resistant metal is stainless steel.
Not only does stainless steel have very high anti-corrosive properties but it is also very strong and ductile. This makes it a popular manufacturing material for a host of applications across a wide range of industries.
Its high corrosion-resistant properties are in direct correlation to its high chromium and nickel content (chromium:16-25%, nickel:35%), allowing it to form an added protective layer that helps prevent corrosion from reaching its interior surface.
Aside from corrosion resistance, stainless steel also contains the following properties:
Stainless steel nullifies corrosive compounds that would ordinarily damage its structure, ultimately leading to a longer life cycle for items and parts that are made from it.
Aluminum is a natural corrosive-resistant metal alloy that is recyclable, non-toxic, and maintains its strength under extreme conditions.
Aluminum alloys do not contain any iron, so there is no chance of rust.
Instead, when exposed to corrosive conditions, a natural process known as self-passivation happens. Aluminum oxide is formed on the surface to protect the underlying aluminum from corrosion.
Aluminum is lighter and less expensive than stainless steel, which makes it an attractive material for a host of applications, most notably in the aerospace industry, as well as in the food industry.
Its other major properties include:
Moreover, aluminum is unique as it is one of the only corrosion-resistant metals that can be used for additive manufacturing.
Red metals include copper, brass, and bronze and have approximately the same anti-corrosion levels as stainless steel.
These luxury metals are quite costly, but they remain corrosion-resistant close to 1,000 years.
The three categories of red metals all have distinctive corrosion-resistant compositions.
Copper forms a protective green patina over time which helps it mitigate further corrosion.
Brass is a mixture of copper and zinc, giving it more anti-corrosive properties than copper alone.
Bronze is made up of copper and tin, so it is also more corrosion-resistant than basic copper.
The specific properties and applications for each category of red metals are given below.
| Copper | |
| Properties | Applications |
| Corrosion-resistant Conducts electricity Tough Ductile Attractive color Easy to turn into alloys Catalytic (increased speed of chemical reactions) Recyclable | Architecture Tubes, pipes and plumbing equipment Locks Electric bells Scrapyard cranes Home appliances Starter motors Computers Fans Bicycles Jewelry Industrial machines Copper roofing Electricity substations |
| Brass | |
| Properties | Applications |
Corrosion resistance Easy to form and cast High strength Low friction Low melting point Ductile Malleable Antibacterial Recyclable | Musical instruments (horns & bells) Electrical sockets Hose couplings Ammunition casting Architectural trim Jewelry Tubes, pipes and plumbing equipment Valves Bearings Radiators Zippers Locks Screws |
| Bronze | |
| Properties | Applications |
| Corrosion resistance (especially seawater corrosion) High melting point (1742°F / 950°C) Low metal-on-metal friction Hardness | Marine equipment and fishing components Musical instruments Electrical connectors and components Pump components Sculptures Coins Mirrors Medals Valves Gears Springs Bearings Bushings |
In short, although red metals are not the cheapest corrosion-resistant metal alloys around, their anti-corrosion longevity makes them a popular material within a number of industries.
These alloys are primarily made up of nickel, along with other alloying elements that give them a high degree of corrosion resistance and strength in high temperatures.
In alloys, nickel is usually combined with either iron, copper, molybdenum or titanium.
Moreover, the combination of nickel, chromium and molybdenum or nickel, chromium and cobalt is also common.
Since nickel itself is often used to enhance corrosion protection in other metals, it goes without saying that all forms of nickel alloys are automatically resistant to all forms of corrosive chemicals and environments, including oxidative corrosion.
All forms of nickel-based alloys exhibit the following properties and characteristics:
Because of their corrosion resistance and other chemical and mechanical properties, nickel-based alloys have various applications within the aerospace, marine, chemical, and nuclear industries.
Some of the more common ones include:
The widespread use of these alloys in harsh environments is in direct correlation to their ability to minimize the negative effects of corrosion and perform and maintain their structure in high-temperature settings.
Knowing the properties and applications of the available metals is an important step in selecting the right one.
Just as important, however, is learning the core metal corrosion prevention methods to further boost corrosion protection before and after purchase.
These methods will be covered in the next section.
Most metals are prone to corrosion damage, and the estimated cost of corrosion around the globe is $2.5 trillion per year.
That’s why it is so important to familiarize yourself with the various corrosion prevention methods.
These will not only prevent corrosion but also increase the longevity of any material or item that is susceptible to it.
Combining as many of these methods as possible helps lower costs and degeneration of equipment, components, and systems that operate in highly-corrosive settings.
Since we’ve discussed tackling the risk of corrosion by choosing the right type of material in the previous sections, we list another five of these prevention methods below.
Environmental modifications refer to any method that helps reduce the exposure to oxygen, chloride, sulfur and other corrosive chemicals in a surrounding environment.
Some examples include storing metals indoors and using water softeners.
Organic coatings help reduce the damage caused by environmental gasses on metals.
Examples of organic coatings include:
Paints can also be used as a protective coating against gasses.
Cathodic protection includes methods that convert active areas on metal surfaces to passive ones using two opposing currents.
They are especially effective against galvanic corrosion, which often occurs in ship hulls, oil and gas pipelines, and offshore rigs.
The two types of cathodic protection methods that can be used include the introduction of galvanic anodes or an alternative source of electrical current to metal surfaces.
Plating refers to metallic coatings that help prevent and slow down corrosion, while giving metal surfaces an aesthetic finish.
It includes electroplating (thin layer of metal), mechanical plating (metal powder), electroless (coating metal through the use of a chemical reaction), and hot dipping (molten metal).
As their name implies, these are the chemicals that are used to interrupt the corrosion process on metal surfaces.
Inhibitors form a protective layer on metallic surfaces when they are applied either as a solution or through various dispersion techniques.
Corrosion resistance is one of the most important properties of any piece of equipment made from metal, especially when it comes to those that are used in the aerospace, automotive, and marine industries.
Metals that can stop corrosion will help maintain an item’s structural integrity and functionality.
Businesses that are searching for custom metal parts must do their due diligence to find the material with the optimal properties.
In the above sections, we’ve discussed the basics of choosing the right corrosion-resistant metals, as well as some very important corrosion prevention methods to further enhance corrosion resistance.
While the aforementioned information gives you a strong foundation from which to begin your material selection process, you should also consult a metal expert before making a purchase decision.
To learn more about our selection of corrosion resistant metals and prevention methods, contact us directly via the convenient website form or request a quote here. We welcome your inquiries.
