CPM CRU-WEAR Tool Blade Steel - Heat Treatment Recipe
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CPM CRU-WEAR is an air-hardening powder metallurgy tool steel, heat treatable to HRC 60-65. The original conventionally melted CRU-WEAR was designed as an upgrade to A2 and D2, for better wear resistance, greater toughness and higher attainable hardness. CPM CRU-WEAR was introduced as a way to make the conventionally melted version easier to machine and more resistant to chipping. Compared to the chemistry of D2, (D2 = 1.55% carbon, 11.5% chromium, 0.8% vanadium, and 0.9% molybdenum), CPM® CRU-WEAR® has less carbon and less chromium, but more vanadium and tungsten. The overall carbide content of CPM® CRU-WEAR® is less than D2 which helps make it tougher than D2. CPM® CRUWEAR®’s higher attainable hardness results from the fact that it contains sufficient tungsten and molybdenum to cause a secondary hardening response. Finally, CPM® CRU-WEAR® tempers at a higher range (900-1050°F) than D2 (400-600°F), so it is more compatible with a wide variety of surface treatments.
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Thermal Treatments
Annealing: Heat to 1550-1650°F (840-900°C), hold 2 hours, slow cool 50°F (25°C) per hour to 1200°F (650°C).
Annealed Hardness: About BHN 225/255
Stress Relieving
Annealed Parts: Heat to 1100-1300°F (595-705°C), hold 2 hours, then furnace cool or cool in still air.
Hardened Parts: Heat to 25°F (15°C) below the original tempering temperature, hold 2 hours, then furnace cool or cool in still air.
Hardening
It is customary to use two furnaces: one furnace to preheat and the second furnace to austenitize. This ensures that the transition from the pre-heat temperature to the austenitizing temperature occurs fairly rapidly.
Preheat: Heat to 1550-1600°F (840-870°C), Equalize.
Austenitize: 1850-2050°F (1010-1120°C), Hold time at temperature 20-45 minutes.
Quench: Air or positive pressure quench (2 bars minimum) to below 125°F (50°C). Salt bath treatment, if practical will ensure the maximum attainable toughness for a given hardening treatment.
Temper: 900-1050°F (480-565°C). Double tempering is mandatory, and triple tempering is recommended. Cool to room temperature in between tempers. Temper 2 hours minimum each time or at least 1 hour per inch (25mm) of thickness for sections over 2” (50mm) thick.
Size Change: Approx. +0.15%
Recommended Heat Treatment: For the best combination of toughness and wear resistance, austenitize at 1950°F (1065°C). Temper 3 times at 1000°F (540°C).
Aim hardness: HRC 62 Higher austenitizing temperatures can be used to obtain higher hardness, at a slight decrease in impact resistance. The lower austenitizing temperatures provide the best impact toughness.
Note: Properties shown throughout this data sheet are typical values. Normal variations in chemistry, size and heat treat conditions may cause deviations from these values.
Suggested heat treatment is based on the recommended specifications for use in ovens, high temp salts, and similarly, properly calibrated equipment; and in line with proper industrial standards for quenching. Deviation from industry standards for schedules, equipment, quenching mediums; and hardness testing equipment may result in varied results. The supplied information on this page is on a generalized scale with the above mentioned standards and methods, which is why soak times and similar aspects may vary in time length to include a margin for the available heat treating equipment and steel cross section.
If you are unsure if you have the necessary means to heat treat on-site, we recommend professional heat treating services provided by Rob Ridley at HeatTreat.ca or 403 556 1113.
CKMS Ltd. is not liable or responsible if proper industry heat treating protocols are not applied; particularly and especially if sending to an independent heat treat provider if they do not follow the intended heat treat schedule or standards for that particular steel; or damage they cause while in their possession.