SAE 51B37 Chromium-Boron Steel
The Synergy of Chromium and Boron.
When standard materials are not enough, engineers turn to alloys. But what happens when even standard alloys need a performance edge? You create a hybrid. SAE 51B37 is that advanced material—a chromium alloy steel supercharged with a micro-addition of boron. This powerful synergy creates a steel with the inherent strength and wear resistance of a chromium alloy, combined with the phenomenal and consistent hardenability that only boron can provide.
A Hybrid Approach to Performance
High Strength & Wear
The chromium content provides excellent baseline strength, toughness, and resistance to surface wear.
Exceptional Through-Hardening
The addition of boron acts as a "hardenability multiplier," ensuring a deep and uniform hardness after quenching.
Good Core Toughness
Develops a strong, tough core that is highly resistant to shock loads and fatigue in demanding applications.
Superior Alloy Performance
Offers a distinct performance advantage over both plain carbon and standard boron steels.
Technical Specifications
Chemical Composition
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.35 - 0.40 |
| Manganese (Mn) | 0.75 - 1.00 |
| Chromium (Cr) | 0.70 - 0.90 |
| Boron (B) | 0.0005 - 0.003 |
Mechanical Properties (Quenched & Tempered, indicative only)
| Property | Value |
|---|---|
| Tensile Strength (MPa) | 900 - 1100 |
| Yield Strength (MPa) | ~760 |
| Hardness (Brinell) | 269 - 331 HB |
Common Applications
Similar & Alternative Grades:
Also comparable to other international chromium-boron grades such as 37CrB4.
Frequently Asked Questions about 51B37
What's the advantage of adding Boron to a Chromium steel?
Chromium provides the excellent base strength and wear resistance of an alloy steel. The micro-addition of Boron then acts as a "hardenability multiplier," allowing the steel to achieve a deeper and more uniform hardness during quenching. This makes the heat treatment process more reliable and effective, especially for complex parts.
How does 51B37 compare to a standard alloy like EN18 (SAE 5140)?
While both are chromium steels, the boron in a 51B37 bright bar gives it significantly better and more consistent hardenability. For a given part, 51B37 will be harder and stronger through its entire cross-section after heat treatment, making it a clear performance upgrade.
The Power of Synergy
True performance is born from synergy—the combination of elements to create something greater than the sum of its parts. The Marbrite Standard for SAE 51B37 is our commitment to this principle. We deliver 51B37 bright bars with a precisely controlled chemistry, ensuring the powerful synergy of chromium and boron is perfectly balanced. Build your most critical components with the confidence that comes from a smarter, superior alloy.