CPM MagnaCut Stainless Steel

MagnaCut is a unique powder metallurgical stainless tool steel whose design eliminates chromium carbide in the heat-treated microstructure. The superior combination of strength and wear resistance is achieved by containing only small, highly hard vanadium and niobium carbides, giving CPM MagnaCut properties similar to non-stainless steel CPM 4V.

The absence of chromium carbide also results in increased corrosion resistance. This product provides an excellent combination of knife properties. This stainless steel has a good combination of high hardness and corrosion resistance.

The steel can achieve relatively high hardness, more than 63 HRC without cold heat treatment and more than 64 HRC with cold heat treatment, even reaching 65 HRC.

CPM MagnaCut is a revolutionary stainless steel that has significantly changed the rules of the game for high-performance cutting tools. The steel was developed by Crucible Industries, a leading manufacturer of specialty alloys and steels, located in Syracuse, New York.

However, in terms of corrosion resistance, MagnaCut significantly exceeds most known stainless steels: S35VN, S45VN, SG-2, Elmax, CPM-154, RWL-34. Chromium in the MagnaCut alloy has virtually no effect on carbide formation. Vanadium and niobium take on the function of carbide formation, and chromium and molybdenum are completely focused on resisting corrosion.

In total, the carbide composition of MagnaCut steel is as follows: 0% chromium carbides, 6.5% vanadium carbides and 1.5% niobium carbides. This gives another significant and positive point - relatively large chromium carbides always lead to a decrease in the strength of the alloy, but they are not there, and as a result, this parameter increases significantly compared to analogues. Among the powder corrosion-resistant steels from Crucible Industries LLC, this new product is the strongest. MagnaCut is stronger than Elmax and Vanax Superclean. At the same time, small and extremely hard vanadium and niobium carbides (VC, NbC) provide an extreme increase in wear resistance. In this parameter, MagnaCut is the main competitor of such steels as Vanax Superclean and Elmax. In terms of strength / wear resistance, MagnaCut is on the same level as 4V, but it is incorrect to compare them, since 4V steel is not stainless. The fine carbide structure not only gives MagnaCut high strength and wear resistance, but also makes this steel a leader in the market of similar steels for knives. In terms of ability to maintain a thin edge, MagnaCut steel has no equal. This allows MagnaCut to be used in a wide range of applications, from thin kitchen knives to huge cleavers.

Overall, MagnaCut is probably one of the most balanced stainless corrosion-resistant steels on the market today. In terms of its properties, it is most similar to Vanax Superclean.

The main drawback today is the availability of this alloy, since demand steadily exceeds supply. Therefore, unfortunately, MagnaCut steel is currently used only for the production of exclusive premium knives.

The development of CPM Magnacut was influenced by the research of Dr. Larin Thomas. The renowned metallurgist sought to create a steel with high chromium content for corrosion resistance and vanadium for wear resistance. As a result, CPM Magnacut has the strength of CPM-4V, a hard knife steel used in elite fixed blades, and the rust-proof durability of CPM-20CV, a time-tested premium knife steel used primarily in folding/flip knives. One of the key benefits of CPM Magnacut is its excellent edge retention, which is attributed to its high wear resistance. However, this characteristic can make it somewhat challenging to sharpen. CPM Magnacut is manufactured by Niagara Specialty Metals, which has a long history in the metals industry and is a partner of Crucible Industries.

The development of this stainless steel also benefited from input from Vanadium Alloys Steel Company (VASCO) and Knife Steel Nerds. They made valuable contributions to the selection of materials and steel characteristics. With its exceptional balance of properties, CPM Magnacut quickly became popular with knife makers and users alike, demonstrating its value in the knife industry.

Hardness

CPM MagnaCut stainless steel is known for its impressive combination of hardness and toughness. The hardness of a stainless steel knife determines its ability to resist deformation, while toughness determines its resistance to fracture. CPM Magnacut achieves its high level of hardness due to its fine microstructure, which also contributes to its toughness. Compared to other knife steels, CPM Magnacut has the strength of CPM-4V, a tough-duty steel used in high-quality fixed blades, making it suitable for use in extreme conditions.

Wear resistance

Another important property of CPM Magnacut steel is its wear resistance. This characteristic is vital for keeping the edge of knives sharp during long-term use. CPM Magnacut steel contains carbon, which increases edge stability, hardness and tensile strength, which ultimately increases its wear resistance and abrasion resistance. In contrast, for example, the popular stainless steel for knives 14C28N, cannot compare with CPM Magnacut in terms of wear resistance.

Corrosion resistance

Stainless steels like CPM Magnacut gain their corrosion resistance from the addition of chromium. Corrosion resistance is an important factor for knife users because it helps prevent rust over time and in harsh environments. Although CPM Magnacut contains less chromium carbides than other stainless steels, it makes up for it with increased corrosion resistance. CPM Magnacut's corrosion resistance is comparable to CPM-20CV, a premium knife steel used primarily for folding knives. Overall, this steel has a balanced set of properties that are highly desirable in knife making.

The steel is highly resistant to rust and is well suited for use in salt water. Thanks to its high chromium content and advanced powder metallurgy process, stainless steel resists corrosion well in wet and damp conditions. This makes MagnaCut a great choice for fishermen, divers, and others who need a reliable knife in salt water conditions.

Heat treatment

• Forging: 1150 °C. Do not forge below 950 °C.
• Annealing: Heat to 900 °C, hold for 2 hours, cool slowly at a rate of no more than 15 °C per hour to 595 °C, then cool in a furnace or in air to room temperature. Hardness after annealing: about BHN 235. 

Relieving stress

• Annealed parts: heat to 595 - 705 °C, hold for 2 hours, then cool in a furnace or in air.
• Tempered parts: heat to 15 - 30 °C below the original tempering temperature, hold for 2 hours, then cool in a furnace or in air.
• Straightening: best done at 200 - 425 °C.

Hardening

• Preheating: heating to 845 - 870 °C. Leveling.
• Austenitization: 1065 - 1205 °C, holding time at temperature indicated in the table. Thick sections and large parts may require longer austenitization times.
• Quench: plate hardening, air or positive pressure hardening (minimum 2 bar) to below 50°C, salt hardening or intermittent oil hardening to approximately 540 °C, then air cooling to below 50 °C.
• Cold treatment: cold working can be used after quenching to reduce retained austenite and increase hardness. Tempering before cold working reduces the effectiveness of cold working, but also reduces the likelihood of warping or cracking. Freeze treatment at -23 °C has no effect unless done immediately after quenching without delay.
• Temper: double tempering at 150 - 230 °C. Keep for at least 2 hours each time.
  NOTE: tempering above 400°C will reduce corrosion resistance.
• Size change: +0.05 to +0.10% in martensitic condition. Presence of retained austenite may reduce net growth. When tempering at 150 - 400 °C, freeze treatment may be required to minimize retained austenite.

Recommended heat treatment:

• Austenitization 1120 °C. Quenching to below 50 °C.
• Double temper at 175 °C for at least 2 hours each.
• Cool to hand warm between tempers. Freezing can be added after quenching. Target hardness: 60-63 HRC.

The properties shown on this data sheet are typical values. Normal variations in chemistry, dimensions and heat treatment conditions may cause deviations from these values.

Machinability and grinding

In the annealed condition, CPM MagnaCut is easier to machine than 20CV and S30V. Similar grinding equipment and methods used for high-speed steels are recommended. Aluminum oxide type "SG" or CBN wheels generally give the best results when working with CPM steels.

Physical properties

• Modulus of elasticity 31 X 106 psi: 215 GPa.
• Density (specific gravity) 0.28 lbs./in3: 7.76 g/cm3.
• Thermal conductivity 93 °C W/m-°K: 18,6.
• Coefficient of thermal expansion (20 °C - 200 °C) mm/mm/°C: 11.6 X10^-6.

Application CPM MagnaCut

CPM Magnacut is a versatile knife steel that has earned a reputation for its excellent balance of properties, making it suitable for a variety of applications. And one of the most popular uses for this steel is in the manufacture of kitchen knives. Thanks to its fine microstructure, Magnacut provides exceptional edge retention, ensuring that the knife will remain sharp even after prolonged use.

In addition to kitchen knives, the steel has found its place in the world of knife making due to its excellent properties such as wear resistance, hardness, strength, toughness and corrosion resistance. This stainless powder steel provides edge retention and impact resistance, which are essential factors in creating high-quality knives.

In terms of purpose, CPM Magnacut is an ideal choice for both small components and large cleavers. Its amazing ability to withstand impacts and maintain a sharp edge makes it popular with knife enthusiasts and professionals alike. In terms of strength, this steel is comparable to steels such as CPM 3V, which further confirms its versatility.

The balance of properties of CPM Magnacut steel is its notable advantage. Thanks to its excellent edge retention and superior toughness, it manages to provide excellent performance characteristics without compromising other important qualities. This makes Magnacut the best choice for many knife makers and users looking for an all-round performer.

It is also worth noting that the application of CPM MagnaCut is very diverse and covers a wide range of areas. From kitchen knives to various cutting tools, this steel provides exceptional performance and finds its place in many aspects of knife production.