Nitro-V Stainless Steel

Nitro-V is a high-carbon stainless steel with added nitrogen and vanadium. Vanadium has long been considered a key alloying element for heavily worked steels, from simple tool steels to aerospace components. By increasing grain refinement and promoting carbide formation, it becomes easier to retain and maintain an edge, whether on a razor, a luxury kitchen knife, or a tactical folder.

Nitrogen has only become an industry standard within the last decade. Nitrides boost stain resistance by bonding with the chromium oxide layers that naturally form during grinding and polishing operations. The combination of chromium oxide and nitrogen allows the steel to be exposed to more aggressive environments, particularly and especially wet working conditions, such as professional kitchens or offshore work. Together, nitrogen and vanadium launch Nitro-V into an entirely new category, distinct from any predecessor, allowing it to be used in applications and methods that were previously poorly suited for 14C28N and AEB-L.

Users find that Nitro-V (Nitro V) is easy to work with in both annealed and hardened conditions while providing the most economical use of consumables, such as belts, or an easy heat treatment when compared to other super stainless steels. Due to its characteristics, Nitro-V is ideally suited in most material removal situations, such as water-jet cutting or metal band sawing in the annealed condition, and is relatively forgiving when grinding a fully hardened blank. Due to the material properties, swarf (chips) is typically large and easily removed despite its abrasive wear resistance characteristics. As it is so relatively easy to grind, it also polishes with minimal extra needs or materials. The maker can be confident that hand grinding Nitro-V will be no more difficult than their standard carbon or simple stainless knife. One of two heat treatment methods is recommended, with and without cryo treatment, but its chemistry requires only minimal sub-zero treatment within the range of -98°F to -94°F for the minimum time needed only to soak and cool the steel. In this way, Nitro-V is not only an economical choice as a material but provides the maker with a steel that is just as low in production costs.

Chemical composition

Comparative characteristics of four steels: 440C, Nitro-V, 420HC, and S30V

Key observations:

1. Edge Retention: S30V shows the best results. Nitro-V significantly outperforms 440C and 420HC.
2. Corrosion Resistance: S30V shows the best resistance (lowest rate), followed closely by Nitro-V, which significantly surpasses both 440C and 420HC.
3. Hardness: Nitro-V achieves the highest hardness level among the compared steels – approximately 62 HRC.
4. Impact Toughness: Nitro-V has significantly higher impact toughness (break strength) than any other steel in the test, leading the pack by a large margin.
5. Bending Strength and Tensile Strength: in these categories, Nitro-V demonstrates competitive results, close to S30V and higher than the classic 440C and 420HC.

Heat treatment

Important - Pre-Processing | Quenching (with Cryo Treatment)

• Blades should be cleaned by washing with soapy water and then placed either in a foil pouch or coated with a high-temp anti-scale / anti-decarburization compound prior to heat treatment if oxygen-free heat treatment equipment is not being used.
• Skipping steps such as pre-heat, temperature equalization, or cryo treatment will result in lower hardness, greater retained austenite (RA), poorer stain resistance, or other issues. Raise the temperature as fast as possible (AFAP) between pre-heat and austenitizing temperature.
• It is recommended to compress flat parts (clamp) after quenching during cryo or tempering to avoid thermal shock induced warping.
• Figures (figures/data) presented represent positive pressure quenching using aluminum plates and compressed air to a temperature of 125°F / 50°C or below - alternative quenching methods may result in lower hardness, high retained austenite (RA), or other issues.

Cryogenic treatment

• Cryogenic treatment is recommended to convert retained austenite, and it can be performed both before and after the first temper cycle.
• While liquid nitrogen is the preferred option, a sub-zero bath of dry ice and kerosene will be sufficient to achieve a temperature of -100°F / -74°C.
• Soak for sub-zero treatment for 1 hour, depending on the thickness and quantity of blades.
• Cryogenic treatment can be done immediately after quenching, but it is recommended that the blades are clamped flat to avoid thermal shock-induced warping. Cryo treatment should always be followed by a temper cycle.

Tempering (with Cryo Treatment)

• Once the blade is quenched and has approached room temperature, it should be tempered appropriately. The suggested tempering time is required to ensure an even and stable temperature.
• Figures provided align with industry standards.
• If you are using a small toaster oven or domestic kitchen oven for tempering, using a blade stand made of kiln materials, a sheet pan lined with fine sand, or a similar large object will help hold thermal mass. This reduces significant temperature fluctuations while the appliance attempts to maintain the temperature.
• Note: final hardness values differ based on starting hardness after quenching and the percentage of conversion to martensite. Only reliable testing methods, such as a calibrated Rockwell hardness tester, can provide actual hardness values. Conversely, files and chisels for hardness calibration are relative testing methods and are inaccurate for reading the true hardness value.
• Temper twice for 2 hours each.

Manufacturers caution against tempering at temperatures of 800°F / 425°C and above, as this will lead to sensitization (increased susceptibility to intergranular corrosion) and, consequently, a reduction in toughness and corrosion resistance.

Important - Pre-Processing | Quenching (without Cryo Treatment)

• Blades should be cleaned by washing with soapy water and then placed either in a foil pouch or coated with a high-temp anti-scale / anti-decarburization compound prior to heat treatment if oxygen-free heat treatment equipment is not being used.
• Skipping steps such as pre-heat, temperature equalization, or cryo treatment will result in lower hardness, greater retained austenite (RA), poorer stain resistance, or other issues. Raise the temperature as fast as possible (AFAP) between pre-heat and austenitizing temperature.
• It is recommended to compress flat parts (clamp) after quenching during cryo or tempering to avoid thermal shock induced warping.
• Figures presented represent positive pressure quenching using aluminum plates and compressed air to a temperature of 125°F / 50°C or below - alternative quenching methods may result in lower hardness, high retained austenite (RA), or other issues.

Tempering (without Cryo Treatment)

• Once the blade is quenched and has approached room temperature, it should be tempered appropriately. The suggested tempering time is required to ensure an even and stable temperature.
• Figures provided align with industry standards.
• If you are using a small toaster oven or domestic kitchen oven for tempering, using a blade stand made of kiln materials, a sheet pan lined with fine sand, or a similar large object will help hold thermal mass. This reduces significant temperature fluctuations while the appliance attempts to maintain the temperature.
• Note: final hardness values differ based on starting hardness after quenching and the percentage of conversion to martensite. Only reliable testing methods, such as a calibrated Rockwell hardness tester, can provide actual hardness values. Conversely, files and chisels for hardness calibration are relative testing methods and are inaccurate for reading the true hardness value.
• Temper twice for 2 hours each.

Manufacturers caution against tempering at temperatures of 800°F / 425°C and above, as this will lead to sensitization (increased susceptibility to intergranular corrosion) and, consequently, a reduction in toughness and corrosion resistance.

Heat treatment disclaimer

• Suggested heat treatment schedules are based on recommended specifications for use in ovens, high-temperature salts, and analogous, properly calibrated equipment, and adhere to proper industry standards for quenching. Deviation from industry standards regarding schedules, equipment, quench media, and hardness testing apparatus may result in varying results. Information provided on this page is generalized and conforms to the above-mentioned standards and methods, thus soak times and similar aspects may vary in duration to incorporate latitude for available heat treatment equipment and steel cross-section.
• If you are unsure you have the necessary means to perform heat treatment in-house, we recommend professional heat treatment services or specialized services from knife material dealers. Check with suppliers to see if they offer HT services and verify that they adhere to industry standards.
• The manufacturer is not responsible if proper industrial heat treatment protocols are not followed, especially if you send the steel to an independent heat treatment service provider and they do not follow the prescribed heat treatment schedule or standards for this steel, or for damage they incur while the steel is in their possession.

Nitro-V is an innovative stainless steel that, thanks to alloying with nitrogen and vanadium, provides an exceptional balance between affordability and high performance, making it an ideal alternative to more expensive super steels. It demonstrates significantly higher hardness (up to 64 RC), better impact toughness, and excellent corrosion resistance compared to classic grades. For manufacturers, Nitro-V is an extremely advantageous choice because it is easy to process (grinding and polishing) and has low production costs, allowing for high final performance characteristics without the need for complex equipment or excessive effort.