C
PM S45VN is a martensitic stainless steel meticulously engineered to provide unparalleled
enhancements in corrosion and wear resistance compared to CPM S35VN. By rebalancing its chemistry, more chromium carbides are formed, while retaining more free chromium within the matrix. The strategic replacement of some Vanadium and Carbon with Niobium and Nitrogen results in an extraordinary combination of edge retention, wear resistance, corrosion resistance, and toughness. This makes it the optimal choice for an everyday carry (EDC) knife steel.
The
CPM process ensures the production of exceptionally homogeneous, high-quality steel. It boasts superior dimensional stability, grindability, and toughness, significantly outperforming steels created through conventional melting practices.
Typical Applications:
Long-Wearing Specialty Cutlery, Plastic Injection, and Extrusion Feed Screws and Dies, Non-Return Valve Components, Pelletizing Equipment, and Wear Components for Food and Chemical Processing. Note: These applications are typical examples; ensure suitability through independent study and evaluation before proceeding with your specific application.
Chemical Composition:
Physical Properties:
Elastic Modulus32 X 10^6 psi
(221 GPa)
Density0.27 lbs./in³
(7.47 g/cm³)
Thermal Conductivity
BTU/hr-ft-°F
W/m-K
cal/cm-s-°C
200°F
93°C
10
17.31
4.13 X 10^-2
Coefficient of Thermal Expansion
°F
°C
in/in/°F
mm/mm/°C
7
0 - 400
(20 - 200)
6.1 X 10^-6
(11.0 X 10^-6)
70 - 600
(20 - 315)
6.4 X 10^-6
(11.5 X 10^-6)
Mechanical Properties:
Toughness(Transverse Charpy C-notch Testing)
While the longitudinal toughness of all four grades is approximately 25-28 ft. lbs., the transverse toughness of CPM grades outshines 440C and 154CM by four or more times. This superior transverse toughness means CPM S45VN, CPM S35VN, and CPM S30V are remarkably more resistant to chipping and breaking under side loading conditions. In knifemaking, this makes CPM particularly suitable for larger blades.
Edge Retention(CATRA Testing Relative to 440C)
T
The CATRA (Cutlery & Allied Trades Research Association) test machine conducts a standardized cutting operation, meticulously measuring the number of silica-impregnated cards that are effectively cut. This test is widely regarded as a benchmark for assessing relative wear resistance. The results in this table are compared against a 440C standard and are based on market feedback, offering an insightful estimate.
Thermal Treatments:
Forging:
Conduct forging at 2100°F (1150°C). Ensure the temperature does not drop below 1750°F (950°C) during the process.
Annealing:
Heat to a precise 1650°F (900°C) and maintain for 2 hours. Then, implement a slow cooling rate of no more than 25°F (15°C) per hour until reaching 1100°F (595°C). Follow with either furnace cooling or still air cooling to room temperature.
Annealed Hardness: Achieves approximately BHN 255.
Stress Relieving Annealed Parts:
For annealed parts: Heat to 1100-1300°F (595-705°C), hold for 2 hours, then cool in a furnace or still air. For hardened parts: Heat to 25-50°F (15-30°C) below the original tempering temperature, hold for 2 hours, then cool in a furnace or still air.
Straightening:
Optimal results are achieved by straightening at a warm temperature of 400-800°F (200-425°C).
Hardening Preheat: Heat uniformly to 1550-1600°F (845-870°C) and ensure temperature equalization.
Austenitize: Heat to a range of 1900-2000°F (1035-1095°C) and maintain the temperature for 15-30 minutes. Quench using air or positive pressure quenching (minimum 2 bar) to below 125°F (50°C), or alternatively, use salt or interrupted oil quenching to approximately 1000°F (540°C), followed by air cooling to below 125°F (50°C).
Temper:
Undertake a double tempering process at 400-750°F (200-400°C), holding for a minimum of 2 hours each time. Refer to the table for guidance. Optionally, implement a freezing treatment between the first and second tempers to achieve optimal hardenability, always followed by at least one additional temper.
NOTE: For the best stress relief, temper CPM S45VN at 1000-1025°F (540-550°C). Be aware that tempering within this range may slightly diminish corrosion resistance.
Size Change:
Expect a size change of +0.05 to +0.10% when in a fully martensitic state. The presence of retained austenite may reduce overall growth. When tempering at 400-750°F (200-400°C), consider freezing treatments to minimize retained austenite.
Recommended Heat Treatment:
Austenitize at 1950°F (1065°C). Quench to below 125°F (50°C). Perform a double temper at 600°F (315°C) for a minimum of 2 hours each. Ensure the material cools to hand warmth between tempers. Including a freezing treatment between tempers is advisable.
Aim Hardness: Targeting a hardness range of 59-61 HRC.
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