Rustproofing blades begins with selecting the proper steel containing the right combination of alloying elements to meet your needs. There are numerous varieties of steel available to manufacture industrial blades, and it’s essential to know how to identify the right components that go into the final product.

You can also use other methods to prevent corrosion on saw blades, such as creating a temporary rustproof patina layer on your carbon steel blades. This coating ensures blades are protected from the damaging effects of rust.

What Is the Importance of Rustproofing Your Blades?

Iron is one of the most abundant and readily accessible materials on Earth. It provides excellent strength, toughness and durability compared to many other building and tool materials like wood, stone or glass. But iron has one major flaw — it’s prone to rust.

Rust or oxidation occurs when a material, such as iron, is exposed to oxygen. Oxygen essentially takes some of the iron’s electrons and gives some of its oxygen atoms. This transfer turns iron metal into iron oxide or rust. The problem with rust is that it has significantly worse mechanical properties compared to iron, such as:

• Lower toughness, meaning lower impact-resistance
• Higher hardness, making it more brittle and more likely to shatter
• Lower compression and tensile strength, leading to shorter life and quicker failure

It’s estimated that the annual global cost of corrosion, including rust, is $2.5 trillion, or 3.4% of the total global GDP. This significant loss shows the incredible amount of resources spent each year to combat corrosion. This remarkable statistic also highlights why businesses should invest in the proper materials and tools. Rustproof tools ensure business owners spend less time and money replacing items prematurely due to corrosion.

What Is Carbide Steel?

Around 2500 B.C., humans discovered a hard, dark metallic material buried underground. What they discovered was iron. As our ancestors began working with this metal, they learned they could change the mechanical properties of iron by subjecting it to various amounts of heat and cooling for different durations. They discovered that if they added ash to molten iron, it would become harder and tougher than iron alone.

Over time, metalsmiths would experiment with varying carbon levels and other minerals, such as tungsten, eventually discovering that the metal would take on additional favorable properties. They found that when adding equal weight amounts of carbon and tungsten, the metal became extremely hard and durable. Eventually, this ratio of iron, carbon and tungsten became known as tungsten carbide or carbide steel.

What Alloys Are Used for Rustproofing Carbide Steel?

Carbide steel is widely used to make all sorts of products and tools, including:

• Drilling and mining tools
• Gears
• Electronics
• Radiation shielding
• Mill tools
• Jewelry
• Saws and knives

The majority of these applications require the carbide metal to be exposed to an oxygen-rich environment. When an iron-containing material is exposed to oxygen, it creates the undesired product, iron oxide. To combat this, alloying elements are added to the carbide steel mixture. Some of the most popular alloying elements include:

1. Chromium

Chromium is one of the more popular alloying elements because it makes the steel dramatically more corrosion resistant, and it’s what makes steel “stainless.” It does this by allowing a layer of oxide material to form on the surface without penetrating beyond five nanometers deep. Typically, the minimum amount of chromium needed to produce a corrosion-resistant oxide layer is 11%. To be safe, manufacturers generally add 18% chromium to most carbide and stainless steels.

2. Nickel

With the addition of nickel, stainless steels and carbide steels become even more corrosion resistant. Nickel also makes the steel behave in a more workable way, aiding in cold temperature ductility. This means that nickel-containing steel is easier to cold-work and form into different forms, including sheets and cylindrical shapes.

Nickel also allows for easier welding of stainless and carbide steel, which opens up a wide array of applications. The amount of nickel added depends on the needs of the steel. Two popular types of steel, 304 and 316, contain 8% and 11% nickel, respectively.

3. Molybdenum

Molybdenum provides very similar benefits to chromium and nickel in that it further enhances the corrosion resistance of the steel. Molybdenum is a large atom, which increases the high-temperature strength of the steel. The increase in high-temperature strength molybdenum offers means the steel can be used in applications that are routinely subjected to a range of fluctuating temperatures — such as heat exchangers and automotive components.

What Are Stainless Steel Carbide Saw Blades?

Stainless steel is an umbrella term that contains many different molecular recipes. All stainless steel products start with iron as their primary element. With the addition of carbon, iron takes on much better mechanical properties, the most important of which is increased hardness. With the introduction of high carbon steel, blades including swords, sheers, spearheads and tools become higher-quality and longer-lasting. In addition, they are able to be sharpened to a finer degree, and their edge lasts longer with more rigorous use.

Other elements such as chromium, nickel, molybdenum and tungsten each uniquely contribute improvements in mechanical properties. Chromium, molybdenum and nickel all aid in corrosion resistance, which is an essential feature of a blade. Often, saw blades and other industrial tools are subjected to high heat, rapidly changing temperatures, moisture, chemicals and other conditions that quickly deteriorate most materials.

With the addition of alloying metals, carbon steel becomes much more resistant to these harmful effects. This allows blades, saws and other tools to have much longer lives, enabling manufacturers to create their products with finer tolerances, higher quality and greater profit margins.

Carbon steel becomes stainless steel with the addition of alloying elements like tungsten, chromium, nickel and molybdenum. These alloys give the stainless steel much higher tensile and compressive strength and better mechanical behavior when at higher or lower temperatures. Alloys also give stainless steel more significant benefits from heat treatment process, including annealing and normalizing:

• Annealing: Annealing involves raising the stainless steel’s temperature to the desired temperature, holding or “soaking” at that temperature, and then cooling the metal, usually to room temperature. When the stainless steel is heated to a specific temperature, its microstructure can relax, releasing internal stresses. When the steel is allowed to cool, the microstructure reforms. If the cooling occurs quickly, like during water or oil quenching, the steel’s microstructure will freeze as it is. This can create large internal stresses in the metal, which alters its mechanical behaviors.
• Normalizing: Normalizing is a process that uses heat to distribute internal stresses more uniformly throughout the material. These internal stresses are created during cold working processes like rolling. Normalizing allows the metal to have similar mechanical properties to its state before it was cold worked.

These processes allow manufacturers to develop the precise corrosion-resistance properties needed for their products. Whether it’s heat treatment through normalizing and annealing or alloying carbon steel, these processes are crucial for making corrosion-resistant saw blades and tools.

Overall, stainless steel and carbide steel are extremely versatile materials with a wide range of applications and a long usable life.

Caring for Corrosion-Resistant Saw Blades and Knives

Alloying elements provide massively increased corrosion resistance compared to non-alloyed ferrous metals, which are those that contain iron. They almost universally increase the strength, hardness and workability of the metal to be formed, pounded, pressed and cut into the desired shape. Even with these alloying elements, corrosion resistance isn’t perfect.

Alloying elements, such as nickel, work by creating a protective surface layer that acts as a sacrificial coating to combat the oxygen-rich atmosphere. The alloy binds up the extra electrons in the ferrous metal, preventing the oxygen molecules from stealing them. However, this protective layer doesn’t last forever. It’s vital to regularly clean, sharpen and care for your stainless or carbide steel blades, knives and tools. Ensure they aren’t needlessly left submerged in corroding chemicals or moisture for extended periods.

How Can I Check if Carbide Blades Are Rustproof?

When it comes to the longevity and effectiveness of blades, you can do several things to ensure your blade has a long service life. The first and most important consideration when looking to rustproof your blade is ensuring it contains the proper amount of alloying elements, including chromium, molybdenum, nickel and tungsten.

These alloying elements provide unique contributions to reducing the corroding effects of moisture and other chemicals. To determine whether the blade contains these alloying elements, you can look up the identification number or American Iron and Steel Institute/Society of Automotive Engineers (AISI/SAE) number.

AISI/SAE numbers are given to metals and other materials in a collaborative effort by various institutes, including the American Iron and Steel Institute, the Society of Automotive Engineers and the American Society of Testing and Materials (ASTM). They serve as a catalog system to classify common metals based on their percentage of specific alloying elements.

Take 1060 plain carbon steel, for example. It doesn’t contain any alloying elements. The first two numbers indicate the alloying content, and the last two digits indicate the weight percent of carbon. So, in the case of 1060 steel, 10 indicates plain carbon steel, and 60 indicates 0.6 weight percent of carbon added to the iron.

These AISI/SAE numbers are extremely handy when determining a blade’s quality and whether it possesses the corrosion-resistance properties you need. Plain carbon steel without alloying elements will quickly begin to rust in the presence of moisture or other corroding chemicals.

AISI/SAE numbers beginning with digits other than 10, such as 4063 alloy steel, contain some form of alloying. By checking 4063 steel, we know it contains 0.63% carbon, 0.75%-1.0% manganese and 0.2%-0.3% molybdenum. This steel doesn’t contain any chromium, nickel or tungsten, indicating that its corrosion resistance might not be as good as metals containing these alloying elements. However, 4063 steel is still widely used in industrial applications, including structural components in ships, vehicles, airplanes, weapons, railways, bridges and more.

The first and most important consideration when looking to ensure your blades are rustproof is making sure they contain sufficient amounts of the alloying elements above. AISI/SAE numbers provide an easy way to quickly search the contents of a particular metal.

Other Methods of Rustproofing Blades

Some blades do not contain sufficient alloying elements to protect them from rusting when in contact with moisture or other corrosive chemicals. As an alternative, users need creative solutions for rustproofing these blades.

Most alloying elements in carbon steel prevent oxygen from reacting with the metal by binding up the free electrons within their molecular arrangement. Others work by creating a thin layer of protection between the ferrous metal and the oxygen-rich environment. Using these principles, we can initiate a protective layer to develop on carbon steel.

Create a Patina Coating

If non-alloyed carbon steel is kept clean, over time, it will develop a surface layer of iron oxide. This isn’t the typical rust you see on metal. This type of iron oxide is called patina and has the chemical formula Fe3O4, while rust has the chemical formula Fe2O3.

Patina is a protective layer that shields the knife surface from creating rust within its oxygen-rich environment. It often appears as a black or grey stain on the surface and can give the knife a sleek appearance. It’s important to distinguish the two chemicals. If the blade has dark brown, red or orange hue or spots, that is rust and not patina.

To create a patina finish on the surface of your carbon steel blade, you need to expose the blade to an acidic environment for an extended time. Coffee or mustard are excellent acidic household ingredients that can do the trick. Coffee is less acidic than mustard, so you can leave your blade soaking in a coffee bath for up to 24 hours to create a patina hue. With mustard, you coat the blade for only 30 minutes to achieve your desired result.

These patina coatings allow your blades to resist the damaging effects of rust for a very long time. With use, the patina coating will eventually be rubbed off, and you’ll need to reapply it.

Choose Oleson Saw Technology for Corrosion-Resistant Saw Blades

Your saw blades are some of the most useful and valuable tools for your business, so it’s crucial to invest in the best. Oleson Saw Technology has been in the knife and saw business since 1994. During this time, we’ve continuously provided customers with high-quality products and experienced service in a wide range of industries, including pulp and paper, manufacturing, food and beverage processing and pharmaceuticals.

For high-quality, corrosion-resistant saw blades and industrial knives, contact Oleson Saw online today or request a free quote. For more information about finding the right blades for your cutting applications, give us a call at 1-800-256-8259.