SAE 10B21 Boron (CHQ) Steel
The Foundation of Flawless Fasteners.
The creation of a high-strength fastener is a journey of transformation. It begins with a steel soft enough to be forged into a complex shape at incredible speeds, and ends with a material hard enough to withstand immense forces. Boron steel is the catalyst for this transformation. A microscopic addition of boron unlocks a dramatic increase in hardenability, allowing for the perfect synergy of excellent cold formability and superior final strength.
The Science of Cold Forming
Cold Heading Quality (CHQ) steel must possess exceptional purity and formability to withstand the intense pressures of modern forging without cracking. The addition of boron is a sophisticated metallurgical tool that gives the steel incredible hardenability after it has been formed. This allows manufacturers to use lower-carbon steels that are easy to form, and still achieve the high strength of a more complex alloy in the final, heat-treated component.
Excellent Cold Formability
Engineered with a clean chemistry and low carbon content for high-speed cold heading and forging without cracking.
Enhanced Hardenability
The microscopic addition of boron allows for a deep, uniform hardness after heat treatment, similar to higher alloy steels.
Consistent Heat Treatment
Provides a predictable and reliable response to quenching and tempering, crucial for the quality control of large batches.
Ideal for Fastener Production
The perfect material for producing high-strength bolts, screws, and complex fasteners like property class 8.8 and 10.9.
Technical Specifications
Chemical Composition
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.18 - 0.23 |
| Manganese (Mn) | 0.70 - 1.00 |
| Boron (B) | 0.0005 - 0.003 |
| Phosphorus (P) | 0.030 Max |
| Sulphur (S) | 0.035 Max |
Mechanical Properties (Quenched & Tempered, indicative only)
| Property | Value |
|---|---|
| Tensile Strength (MPa) | ~830 |
| Yield Strength (MPa) | ~650 |
| Hardness (Rockwell) | 25 - 32 HRC |
Common Applications
Equivalent International Grades
| Standard | Grade |
|---|---|
| DIN / W-Nr. | 20MnB5 / 1.5525 |
Frequently Asked Questions about 10B21
What does the 'B' in 10B21 stand for?
The 'B' signifies that the steel has been treated with Boron. Even in microscopic amounts (as little as 0.0005%), boron dramatically increases the steel's hardenability, which is its ability to achieve hardness through heat treatment.
What is "Cold Heading Quality" (CHQ)?
CHQ refers to steel wire or bar that is certified to be of exceptional purity and uniformity, making it suitable for the high-speed, high-pressure process of cold heading or forging. It is designed to be shaped into complex parts like bolts and screws without cracking.
Why use Boron steel instead of a higher carbon steel for bolts?
It's about the manufacturing process. High-carbon steel is too hard to be easily formed into a complex bolt shape. Low-carbon Boron steel like a 10B21 bright bar is soft and ductile, making it easy to forge. After forming, the boron allows it to be heat-treated to achieve the high strength of a much higher-carbon steel.
The DNA of a Reliable Connection
Every machine, every vehicle, every structure is held together by the integrity of its fasteners. The Marbrite Standard for Boron steel is our commitment to providing a flawless foundation for these critical components. We deliver 10B21 CHQ steel with a verified chemistry, ensuring the predictable formability and consistent hardenability your high-volume process demands. Forge your connections with the confidence that comes from a superior material.