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CPM REX 45 Steel: Products, Properties, and Process
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SteelPRO Group is a trusted supplier of CPM REX 45 steel, offering high-performance tool steels for industries like aerospace, automotive, and precision machining. With years of experience, we provide durable, reliable steel solutions in both standard and custom sizes to meet your specific needs.
What Is CPM REX 45 Steel?
CPM REX 45 is a high-speed tool steel made using powder metallurgy (PM) technology. It is a modified variant of M3:2 steel, incorporating 8% cobalt. This alloy provides excellent hardness, superior wear resistance, and durability, ideal for high-speed cutting and challenging machining applications. Compared to M4, REX 45 has slightly lower wear resistance but higher hardness due to its cobalt content. It is widely used in industries requiring precision tools, like aerospace and automotive.
CPM REX 45 Steel Products Forms And Supply Range
We offer a comprehensive range of CPM REX 45 tool steel products in various standard dimensions including bars, rounds, plates, and tooling inserts. We also provide custom-size options.
| Product Form | Dimension | Range (Metric) | Range (Imperial) |
| Bars (Round and Square) | Diameter | 10mm – 100mm | 0.39″ – 3.94″ |
| Length | 300mm – 4000mm | 11.81″ – 157.48″ | |
| Rounds (Solid or Hollow) | Diameter | 12mm – 75mm | 0.47″ – 2.95″ |
| Length | 300mm – 4000mm | 11.81″ – 157.48″ | |
| Plates and Sheets | Thickness | 5mm – 50mm | 0.20″ – 1.97″ |
| Width | 100mm – 2000mm | 3.94″ – 78.74″ | |
| Length | 300mm – 4000mm | 11.81″ – 157.48″ |
CPM REX 45 Steel Chemical Composition
The following table presents the chemical composition of CPM REX 45 tool steel.
| Element | Percentage (%) |
| Carbon (C) | 1.3 |
| Chromium (Cr) | 4.05 |
| Cobalt (Co) | 8 |
| Iron (Fe) | 72.13 |
| Molybdenum (Mo) | 5 |
| Sulfur (S) | 0.060 – 0.22 |
| Tungsten (W) | 6.25 |
| Vanadium (V) | 3.05 |
CPM REX 45 Steel Physical Properties
The table below presents the essential physical characteristics of CPM REX 45 steel.
| Property | Metric | Imperial |
| Elastic Modulus | 214 GPa | 31 × 10⁶ psi |
| Density | 8.05 g/cm³ | 0.291 lbs/in³ |
| Coefficient of Thermal Expansion (70-750°F) | 11.4 × 10⁻⁶ mm/mm/°C | 6.3 × 10⁻⁶ in/in/°F |
| Coefficient of Thermal Expansion (70-1100°F) | 11.5 × 10⁻⁶ mm/mm/°C | 6.4 × 10⁻⁶ in/in/°F |
CPM REX 45 Steel Mechanical Properties
The following table summarizes the mechanical properties of CPM REX 45 steel.
| Property | Metric | Imperial | Note |
| Hardness, Brinell | 255 – 285 | 255 – 285 | Annealed |
| Hardness, Rockwell C | 65 | 65 | Hardening Temp: 1165°C; Tempering Temp: 560°C |
| 67 | 67 | Hardening Temp: 1190°C; Tempering Temp: 550°C | |
| Flexural Strength | 4709 MPa | 683,000 psi | Hardening Temp: 1165°C; Tempering Temp: 560°C |
| 4826 MPa | 700,000 psi | Hardening Temp: 1190°C; Tempering Temp: 550°C | |
| Charpy Impact | 20.0 J | 14.8 ft-lb | Hardening Temp: 1190°C; Tempering Temp: 550°C |
| 27.0 J | 19.9 ft-lb | Hardening Temp: 1165°C; Tempering Temp: 560°C | |
| Modulus of Elasticity | 214 GPa | 31,000 ksi | – |
CPM REX 45 Steel Heat Treatment
Our heat treatment protocol involves meticulous temperature control across various stages, ensuring that CPM Rex 45 achieves its optimal performance characteristics. If you require CPM Rex 45 steel in an annealed state or any other specific condition, please do not hesitate to contact us.
Annealing
Heating the steel to 1600°F (870°C) and maintaining this temperature for two hours. After this, the steel should be cooled slowly at a rate not exceeding 25°F (15°C) per hour until it reaches 1000°F (540°C). Finally, it should be allowed to cool in the furnace or still air to room temperature. The annealed hardness is approximately BHN 255 – 285.
Stress Relieving
For annealed parts, stress relieving is achieved by heating the steel to a temperature between 1100-1300°F (595-705°C) and holding it for two hours, followed by furnace cooling or cooling in still air. For hardened parts, the process involves heating to 25°F (15°C) below the original tempering temperature, or a minimum of 1000°F (540°C), holding for two hours, and then cooling as before.
Hardening
Pre-heat
Heat the steel to 1500-1550°F (815-845°C) and hold it long enough to ensure thorough soaking. For vacuum heat treatment, an extra preheating step at 1850-1900°F (1010-1040°C) is suggested to reduce the duration required at the austenitizing temperature.
Austenitize
The austenitizing process involves heating the steel to a temperature range of 2100-2190°F (1150-1200°C). To achieve HRC 66-68, the standard recommendation is to heat the material to 2175°F (1190°C).
Quench
Quenching should be done rapidly to bring the temperature below 1100°F (595°C), equalizing, and then air cooling to hand warm, below 125°F (50°C). Salt or interrupted oil quenching is preferred for achieving the best heat treatment response.
Tempering
This should be performed at a minimum of 1000°F (540°C). Triple tempering is required, with each tempering cycle held for a minimum of two hours at the specified temperature, and cooling to room temperature between each cycle.
Straightening
Straightening is best performed warm, at a minimum of 400°F (205°C). It is preferred to straighten the steel after salt quenching and before cooling it below 400°F (205°C).
Machinability of CPM REX 45
CPM REX 45 offers good machinability due to its uniform microstructure from the powder metallurgy process. The fine carbide distribution makes it easier to machine than traditional high-speed steels. Machining CPM REX 45 can use carbide or high-speed steel tools, with slower feed rates and cutting fluids to reduce wear and heat.
For grinding, CBN wheels are a great choice, and adding coolant helps maintain a smooth and precise finish while preventing overheating. Just keep your tools sharp and control the speeds, and you’ll get the best results with ease!
CPM REX 45 Steel Applications
Some frequent uses of CPM REX 45 include:
- Cutting Tools: End mills, drills, and reamers for machining hard materials.
- Forming Tools: Punches, dies, and stamping tools for precision manufacturing.
- Cold Work Tools: Tools subject to high mechanical stress.
- Precision Inserts: For turning, milling, and grinding operations.
- Wear Parts: Components like bearings and conveyor systems facing continuous abrasion.
CPM REX 45 Steel VS M4 Steel
CPM REX 45 has higher hardness due to its 8% cobalt content. M4 offers better wear resistance because of its higher vanadium content. M4 also has superior toughness due to its finer carbides.
While CPM REX 45 excels in applications requiring hardness and precision, M4 is better for tools that need both durability and toughness over long-term use.
Premium CPM REX 45 Steel From SteelPro Group
At SteelPRO Group, we offer more than just CPM REX 45 steel. We also offer an extensive selection of premium materials, including H13 steel, to fulfill your machining requirements. With years of experience serving industries like aerospace and tooling, we will help you find the right steel for your projects.
