Tool steel is a special class of alloy steels designed to make tools, dies, molds, and other industrial equipment that must withstand extreme stress, abrasion, and high temperatures. Known for its hardness, toughness, and wear resistance, tool steel is indispensable in manufacturing, construction, and engineering industries.
However, a common question arises: is tool steel rust proof? The short answer is no. Tool steel, like most steels, is not naturally rust proof. While it offers excellent performance in terms of strength and durability, corrosion resistance is not its primary property. In this article, we will explore why tool steel is not rust proof, how it compares to stainless steels, and what methods can be used to protect tool steel from rusting.
Tool steels are alloy steels formulated with elements such as tungsten, molybdenum, vanadium, and chromium. These alloying elements enhance hardness, wear resistance, and toughness. Tool steel is typically used for:
Cutting tools like drills, milling cutters, and saw blades
Dies for stamping, forging, and extrusion
Molds for plastics and casting
Industrial machinery components
Knives, chisels, and precision instruments
Its design focus is on mechanical performance, not corrosion resistance.
Rust resistance in steel comes primarily from chromium. Stainless steels usually contain at least 10.5% chromium, which forms a passive oxide layer that protects against rust. Tool steels, while they may contain some chromium, generally have lower levels compared to stainless steel, meaning they cannot form the same protective layer.
Tool steels have higher carbon content, which increases hardness but reduces corrosion resistance. High-carbon steels are more susceptible to oxidation in humid or corrosive environments.
When exposed to moisture, oxygen, and especially salts or acids, tool steels will corrode. This is why rust is often observed on cutting tools, blades, or dies left unprotected.
Tool Steel: Designed for hardness, wear resistance, and high-temperature performance. Not inherently corrosion resistant.
Stainless Steel: Designed with high chromium and nickel content for corrosion resistance, though it may not achieve the same hardness as tool steel.
Conclusion: If corrosion resistance is more important than hardness, stainless steel may be a better choice. If extreme hardness and wear resistance are critical, tool steel is preferred but requires protection against rust.
While tool steel is not rust proof, several methods can extend its life and protect it from corrosion:
Plating (Nickel, Chrome, or Zinc): Adds a protective barrier against oxidation.
Black Oxide Coating: Provides mild corrosion resistance and reduces glare.
PVD and Nitriding: Surface hardening and protective coatings improve wear and corrosion resistance.
Applying oil, grease, or protective sprays prevents moisture contact, which significantly slows rust formation.
Tools should be stored in dry environments with controlled humidity. Desiccants and rust inhibitors can be used in storage boxes or warehouses.
In some cases, tool steels can be clad with stainless steel layers to combine hardness with corrosion resistance.
Regular cleaning and inspection ensure that any early signs of rust can be addressed before spreading.
Least resistant to corrosion, as they lack significant alloying elements for rust protection.
Better wear resistance but still prone to rust if not protected.
Perform well at high temperatures, but not designed to resist rust in corrosive environments.
Contain more alloying elements, offering slightly improved corrosion resistance, but still not rust proof.
Tough and impact-resistant but need protective measures against rust.
In industries where corrosion is a concern, tool steel may not be the best choice unless properly protected. For example:
Marine Applications: High humidity and salt exposure demand stainless or specially coated tool steels.
Food Processing: Requires stainless steel for hygiene and corrosion resistance.
Chemical Processing: Stainless or nickel alloys are used instead of tool steels to resist aggressive chemicals.
Even though tool steel is not rust proof, it remains the preferred material for tools and dies because corrosion can be managed with preventive measures. By applying protective coatings and maintaining proper handling, tool steel can deliver long-lasting performance in critical applications.
When selecting tool steel, it is crucial to source from suppliers who provide certified grades and guidance on corrosion protection. Companies like sakysteel supply a wide range of tool steels with proper heat treatment and surface finish options to maximize performance. By partnering with sakysteel, industries gain access to high-quality tool steel solutions that balance hardness, toughness, and corrosion management.
Tool steel is not rust proof. While it excels in hardness, wear resistance, and high-temperature strength, its corrosion resistance is limited compared to stainless steels. However, with proper coatings, lubrication, storage, and maintenance, rust formation can be minimized, ensuring tool steel delivers reliable performance.
For applications demanding maximum hardness and durability, tool steel remains the best choice, provided that adequate rust protection strategies are applied. In industries where corrosion resistance is a priority, stainless steel or other alloys may be more suitable. Ultimately, understanding the strengths and limitations of tool steel helps industries make informed material choices for long-term efficiency and reliability.