CPM REX 45 vs Maxamet Knife Steel Comparison

CPM REX 45 vs. Maxamet: A Comprehensive Knife Steel Comparison

Below is a comprehensive comparison of CPM REX 45 and Maxamet steels. This article is aimed at knife enthusiasts and collectors who want to better understand each steel’s chemical composition, hardness, key performance characteristics, and ideal uses. We delve into aspects such as edge retention, toughness, corrosion resistance, ease of sharpening, heat-treatment nuances, and more. By the end, you should have a clear picture of which steel suits your needs best.

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1. INTRODUCTION

Knifemakers and collectors are always on the lookout for steels that push the boundaries of sheer performance. Two such steels that often appear on that “best of the best” list are Crucible’s CPM REX 45 and Carpenter Technology’s Maxamet. Although both are high-end, powder-metallurgy steels known for remarkable edge retention, they differ in several key areas, including toughness levels, ease of sharpening, and corrosion resistance.

In this post, we will compare CPM REX 45 vs. Maxamet by looking at their composition, typical hardness ranges, forging and heat-treatment considerations, patina or coating requirements, and real-world performance in tasks like bushcraft, EDC, kitchen use, and more.

<details> <summary><strong>Key Takeaways</strong></summary>

• Both CPM REX 45 and Maxamet are not stainless (low chromium content).
• CPM REX 45 offers slightly better toughness and ease of sharpening.
• Maxamet pushes hardness (up to around 70 HRC) for elite edge retention.
• Both rely on modern, carefully controlled heat-treatment processes.
• Maintenance with a protective oil or coating is strongly recommended.

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2. STEEL OVERVIEW

2.1 CPM REX 45: Composition and Background

Crucible Particle Metallurgy (CPM) REX 45 is a powder-metallurgy high-speed steel formulated with several alloying elements in relatively high proportions, enabling it to reach very high Rockwell hardness levels. Below is a simplified breakdown of its composition (approximate values):

• Carbon: ~1.3% – Enhances hardness and edge retention.
• Chromium: ~4.0% – Provides a bit of corrosion resistance, though not enough to classify it as stainless.
• Cobalt: ~8.0% – Increases hardness and wear resistance, especially at higher temperatures.
• Molybdenum: ~5.0% – Improves toughness and wear resistance.
• Tungsten: ~6.25% – Raises hot hardness and further improves wear resistance.
• Vanadium: ~3.0% – Forms hard vanadium carbides that significantly boost wear resistance.

REX 45 is often likened to steels like CPM M4 or other high-speed steels. It can achieve excellent edge retention and can be taken to high hardness levels (HRC 64–66), making it a favorite among those who prioritize cutting performance over ease of maintenance.

<details> <summary><strong>Why Choose CPM REX 45?</strong></summary>

• Offers a balanced combination of wear resistance and (relative) toughness for a high-speed steel.
• Achieves extreme hardness without becoming as brittle as some of the ultra-hard powders.
• Ideal for EDC, light to moderate bushcraft, and even kitchen roles if properly maintained.

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2.2 Maxamet: Composition and Background

Carpenter’s Maxamet is a powder-metallurgy “micro-melt” steel that pushes the limits of edge retention and hardness. According to reference data, its typical composition is:

• Carbon: ~2.15% – Extremely high carbon content for outstanding hardness.
• Chromium: ~4.75% – A moderate amount, so it is not stainless.
• Cobalt: ~10.0% – Substantially increases hot hardness and wear resistance.
• Tungsten: ~13.0% – Contributes to extreme wear resistance and high hardness.
• Vanadium: ~6.0% – Creates very hard carbides for edge retention.
• Molybdenum: ~1.0% – Though relatively small, helps with toughness and heat-treatment stability.

Maxamet’s claim to fame is its ability to reach incredibly high Rockwell hardness levels (typically HRC 66–70) while maintaining a super-thin and stable edge. As a trade-off, it ranks lower in toughness than many other steels, and it is somewhat prone to corrosion if neglected.

<details> <summary><strong>Why Choose Maxamet?</strong></summary>

• Nearly unmatched edge retention at extreme hardness levels.
• Excellent choice for specialized cutting tasks where lateral stress is minimal.
• Highly sought-after by collectors and enthusiasts of top-tier, ultra-hard steels.

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3. DETAILED ALLOY ELEMENT EFFECTS

Both steels rely on a carefully balanced cocktail of carbon, tungsten, molybdenum, cobalt, and vanadium to achieve their high hardness and superior wear resistance. Below are a few quick highlights of what these key elements do:

• Carbon (C): Primary hardening element; higher carbon content typically means higher potential hardness and increased wear resistance.
• Chromium (Cr): Offers some corrosion resistance and contributes to wear resistance. Steels below ~10–13% are not considered stainless.
• Tungsten (W): Promotes “red hardness,” meaning the ability to retain hardness at high temperatures. Also boosts wear resistance significantly.
• Molybdenum (Mo): Improves toughness, hardenability, and helps reduce brittleness.
• Vanadium (V): Forms extremely hard vanadium carbides, greatly improving wear resistance and edge stability.
• Cobalt (Co): Often added to high-speed steels to help maintain hardness under extreme stress or temperatures; increases overall wear resistance.

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4. TYPICAL HARDNESS (ROCKWELL C) RANGES AND PRACTICAL IMPLICATION

• CPM REX 45: Typically falls in the HRC 64–66 (or even higher) range when optimally heat-treated. At these hardness levels, you can expect outstanding edge retention and above-average wear resistance. The higher the hardness, the more care needed to avoid chipping or cracking during heavy impacts.
• Maxamet: Famous for hitting HRC values around 66–70. This enormous hardness translates into some of the best edge retention on the market, but it comes at the expense of toughness and ease of sharpening. Overly thin edges may chip if subjected to heavy prying or torque.

In practical use, both excel in slicing and push-cutting tasks, but users must be mindful of potential chipping—especially for Maxamet—during heavy-duty or high-impact use.

<details> <summary><strong>Hardness vs. Toughness</strong></summary>

• Higher Rockwell values increase wear resistance but can reduce impact resistance.
• Consider your use-cases: if you frequently do prying or batoning, a steel with lower hardness might be safer against chipping.

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5. HEAT-TREATMENT NUANCES AND FORGING

Both CPM REX 45 and Maxamet benefit from precise, well-controlled heat-treatment protocols:

CPM REX 45

• Requires exacting heat treatment with multiple tempering cycles to fully develop its wear resistance and toughness.
• High alloy content can lead to distortion or cracking if not handled with proper temperature controls.

Maxamet

• Even more challenging to heat-treat, often requiring carefully controlled high temperatures and cryogenic cycles.
• Its high tungsten and cobalt content easily leads to warping or brittleness if any step in the process is rushed or done incorrectly.

Neither steel is typically forged in the traditional sense by custom makers; their high-alloy compositions demand specialized equipment and well-regulated processes. Hand-forging can result in cracking or excessive distortion.

<details> <summary><strong>Takeaway for Custom Makers</strong></summary>

• Strictly follow manufacturer-recommended austenitizing and tempering temperatures.
• Cryogenic treatment (e.g., liquid nitrogen) often improves results for Maxamet and can be beneficial for CPM REX 45.

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6. PATINA FORMATION AND PROTECTIVE COATINGS

• CPM REX 45: With only about 4% chromium, it is more prone to rust and patina formation than typical stainless steels. Users often note a light patina forming with exposure to acidic foods or other corrosive substances. A protective coat of oil or wax can help reduce corrosion.
• Maxamet: Around 4.75% chromium—still below the stainless threshold—so it is also susceptible to corrosion. Many users observe a gray or bluish patina forming when regularly cutting acidic foods.

Knife manufacturers may apply proprietary coatings, and users are encouraged to keep these steels lightly oiled when not in use, especially in humid or saltwater environments.

<details> <summary><strong>Patina Tips</strong></summary>

• A controlled “forced patina” (using vinegar, mustard, or other mild acids) can add some protection and an attractive finish.
• Always dry the blade thoroughly after cutting or washing to prevent rust.

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7. KEY PERFORMANCE CHARACTERISTICS

7.1 Edge Retention

• CPM REX 45: Known for excellent edge retention, on par with other high-speed steels like CPM M4.
• Maxamet: Ranking near the top in edge retention, Maxamet keeps a keen cutting edge for an extremely long time.

7.2 Toughness

• CPM REX 45: Provides a decent balance of hardness and (relative) toughness within its category.
• Maxamet: More brittle, with a lower toughness rating. Thin edges can be prone to micro-chipping or catastrophic failure under sudden impact.

7.3 Corrosion Resistance

• CPM REX 45: Not stainless; requires some maintenance and care to prevent rust.
• Maxamet: Also not stainless; it can resist rust slightly better than REX 45 but still needs diligent care.

7.4 Ease of Sharpening

• CPM REX 45: Challenging but still more manageable than Maxamet due to slightly lower hardness.
• Maxamet: Among the most difficult steels to sharpen, demanding diamond or CBN stones.

<details> <summary><strong>Recommended Sharpening Methods</strong></summary>

• Use diamond or cubic boron nitride (CBN) stones for both steels.
• Refine your technique to avoid overheating or burring edges, especially with Maxamet.

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8. REAL-WORLD APPLICATIONS

8.1 Bushcraft and Survival

• CPM REX 45: Capable of repeated slicing, wood carving, and moderate prying.
• Maxamet: Excels in slicing but more prone to chipping if subjected to heavy batoning or torque.

8.2 EDC (Everyday Carry)

• CPM REX 45: A tough, high-wear-resistant option that won’t dull quickly.
• Maxamet: Hard to beat for pure cutting performance, but requires extra care in humid or corrosive conditions.

8.3 Kitchen Use

• CPM REX 45: Holds a fine edge for a long time but must be cleaned and dried promptly after contact with acidic foods.
• Maxamet: Superb slicing capability in the kitchen—just be sure to wipe it down often and store it dry.

8.4 Tactical or Military Applications

• CPM REX 45: Provides reliability and high wear resistance; somewhat more robust in tough conditions than Maxamet.
• Maxamet: Outstanding edge retention but may chip if subjected to extreme, high-impact scenarios.

<details> <summary><strong>Where to Find Them</strong></summary>

• Many premium knife brands (e.g., Spyderco) produce limited or sprint runs in CPM REX 45 or Maxamet.
• Custom knife makers also offer specialized designs but expect higher costs and sporadic availability.

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9. COST, AVAILABILITY, AND MAINTENANCE

• Cost: Both are considered premium steels, though Maxamet can sometimes be pricier due to its extreme properties and more complex manufacturing process.
• Availability: CPM REX 45 is increasingly common in special runs or limited-edition production knives. Maxamet also appears in special production runs but can be more difficult to find consistently.
• Maintenance: Keep both steels clean and dry, especially in humid climates. Occasional application of a light oil or rust inhibitor is prudent. Employ diamond or CBN abrasives for best results when sharpening.

<details> <summary><strong>Pricing Tips</strong></summary>

• Prices can vary widely, depending on the manufacturer and blade design.
• Watch for limited-edition “sprint runs” to acquire these steels at moderate (yet still premium) prices.

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10. PROS AND CONS

Below is a quick side-by-side list:

CPM REX 45

Pros:

• Excellent edge retention
• Good balance of hardness and (relatively higher) toughness within its class
• Slightly easier to sharpen compared to Maxamet

Cons:

• Not stainless; prone to rust if neglected
• Still challenging to sharpen compared to simpler steels
• Limited availability in some markets

Maxamet

Pros:

• Outstanding, top-tier edge retention
• Holds an ultra-fine edge for a very long time
• Highly sought-after for specialized cutting applications

Cons:

• Extremely difficult to sharpen
• More brittle; higher chipping risk under lateral stress
• Also not stainless; extra care needed to prevent corrosion

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11. QUICK REFERENCE COMPARISON TABLE

	CPM REX 45	Maxamet
Carbon Content	~1.3%	~2.15%
Tungsten Content	~6.25%	~13%
Cobalt Content	~8%	~10%
Typical Hardness (HRC)	64–66	66–70
Edge Retention	Excellent	Elite
Toughness (Relative)	Moderate	Lower
Corrosion Resistance	Low (not SS)	Low–Medium
Ease of Sharpening	Difficult	Very Hard

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12. IDEAL USES AND WHY CHOOSE EACH ONE

CPM REX 45

• Ideal For: Those who want high wear resistance and a fair degree of toughness in a premium steel. If your use-case involves repetitive cutting or slicing (EDC, moderate bushcraft, or even some kitchen roles), REX 45 provides a strong balance.
• Reasons to Pick: Robust enough to handle occasional impacts and slightly more manageable to sharpen than Maxamet.

Maxamet

• Ideal For: Users who need or crave the absolute longest-lasting cutting edge—like specialized slicers, high-precision cutting tasks, or personal collections focusing on “highest hardness steels.”
• Reasons to Pick: Despite the high cost and maintenance demands, many enthusiasts choose Maxamet for its nearly unmatched edge retention. Best for tasks that don’t involve frequent prying or hard lateral stress.

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13. CONCLUSION

CPM REX 45 and Maxamet are both premium, powder-metallurgy steels that offer remarkable cutting performance, but each has a distinct personality:

• CPM REX 45 places emphasis on a more balanced approach, blending high wear resistance with a slightly better toughness profile (for its class). It can handle a broader range of cutting tasks with a bit less risk of chipping.
• Maxamet centers on extreme edge retention at the highest possible hardness (up to ~70 HRC). The trade-off is lower toughness, more challenging sharpening, and stricter maintenance routines.

Ultimately, your decision depends on your cutting needs and your tolerance for sharpening difficulty and maintenance:

• If you prefer a steel that’s extremely wear-resistant yet still allows for somewhat easier sharpening, CPM REX 45 is likely the better fit.
• If you crave the pinnacle of edge retention and don’t mind a steel that demands diamond stones and meticulous care, Maxamet will satisfy that urge for an elite cutting experience.

Regardless of which you choose, both CPM REX 45 and Maxamet demonstrate the apex of modern metallurgical achievements. With mindful maintenance—keeping blades clean, dry, and possibly coated—you’ll enjoy knives that perform and last for the long haul. Whether for collecting, everyday carrying, or specialized tasks, they rank among the finest edges you can own.

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Bonus FAQ (SEO Optimization)

1. Is CPM REX 45 rustproof?
   No. With only about 4% chromium, CPM REX 45 is more prone to rust than stainless steels. Wipe it dry and oil it regularly.

2. How hard is Maxamet steel to sharpen?
   Very hard. You’ll need diamond or CBN stones for best results, and even then, it requires patience and skill.

3. Which steel is best for bushcraft—CPM REX 45 or Maxamet?
   Most people prefer CPM REX 45 for bushcraft due to its slightly better toughness. Maxamet may chip if stressed laterally.

4. Are there cheaper alternatives to these steels with comparable performance?
   CPM M4, K390, and some other high-speed or tool steels can offer good performance, but may not match Maxamet’s extreme hardness or REX 45’s specific alloy balance.

5. Do major brands offer production knives in these steels?
   Yes. Spyderco, for example, has offered limited or sprint run knives in both CPM REX 45 and Maxamet. Other brands and custom makers occasionally feature them as well.

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By incorporating regular maintenance practices—like immediately wiping down your blade after cutting acidic foods, lightly oiling it before storage, and using the proper sharpening tools—you can ensure that either CPM REX 45 or Maxamet performs at its peak for years to come. Enjoy exploring the cutting-edge realm of modern knife steels!