20MnB4 Cold Heading fasterner Alloy Steel 1.5525 SWRCHB22K C20B
Details
20MnB4 is a European standard low-carbon boron cold forming steel (material No.1.5525, EN 10263), specially designed for cold heading fasteners. Trace boron significantly improves hardenability without raising carbon content, combining excellent cold plastic deformation capacity and stable quenching-tempering mechanical properties. It is widely supplied as wire rod, drawn wire and hot rolled round bars for mass production of high-strength bolts, studs and automotive fasteners.
Chemical Composition (Mass Fraction, wt.%)
| Element | Content Range | Metallurgical Function |
|---|---|---|
| C | 0.17–0.24% | Low carbon guarantees superior cold ductility, avoids cracking during heading |
| Si | ≤0.40% | Mild deoxidation, reduce surface decarburization |
| Mn | 0.90–1.40% | Refine grain, boost strength and hardening depth |
| B | 0.0008–0.0035% | Core boron element, drastically enhance deep hardenability |
| P | ≤0.030% | Limit cold brittleness of finished fasteners |
| S | ≤0.030% | Prevent hot cracking during wire rolling and forging |
International Equivalent Grades
| Region | Grade | Standard Reference |
|---|---|---|
| Europe | 20MnB4, 1.5525 | EN 10263-3 |
| USA | 10B21 | SAE J403 boron fastener steel |
| Japan | SWRCHB22K | JIS G3507 cold heading wire rod |
| China | 20MnB | Q/BQB 517 CHQ boron steel |
| ISO | C20B | ISO 4954 cold forming steel |
Key Performance & Heat Treatment
Delivered in spheroidizing annealed state, low hardness for smooth drawing, phosphating and cold heading without splitting.Standard heat treatment: Quench 870–900℃ oil cooling + temper 420–460℃. Finished fasteners steadily reach Class 8.8 / 9.8 mechanical performance, with good fatigue resistance for dynamic load parts.Advantages over ordinary carbon steel: Less distortion after heat treatment, uniform hardness across thick bolt cross-sections, lower die wear during cold extrusion.
Main Application Fields
- Automotive fasteners: Engine bolts, suspension studs, wheel hub bolts, chassis connecting screws
- Construction & machinery: High-strength hex bolts, flange bolts, self-stud bolts for equipment assembly
- New energy accessories: Solar bracket fasteners, battery module connecting studs
- Cold extruded small structural parts: Small pins, sleeves, tubular cold forged components
Available forms: Φ5.5–22mm hot rolled wire rod coils, phosphating fine drawn wire, hot rolled black round bars. Cost-effective and stable batch supply for global fastener manufacturers.
Contact us
008617701706555
Room 903, Canyang Zone, No.1016 Youyi Road, Baoshan District, Shanghai, P.R.China
