1. Chemical Composition
304HC is an austenitic stainless steel optimized for cold heading, with adjusted composition based on standard 304 to enhance formability.
| Element | C | Si | Mn | P | S | Cr | Ni | Cu |
| Content(%) | ≤0.08 | ≤1.0 | ≤2.0 | ≤0.045 | ≤0.03 | 18.0-20.0 | 8.0-10.5 | 1.0-3.0 |
Low Carbon (C≤0.08%): Reduces intergranular corrosion risk and improves ductility.
Copper (Cu 1.0-3.0%): Significantly boosts cold formability, lowers work hardening rate, and reduces die wear.
Controlled Impurities (S≤0.03%, P≤0.045%): Minimizes brittleness and cracking during high-speed cold heading.
2. Physical Properties (Annealed Soft State)
| Property | Value |
| Tensile Strength | 520-650 MPa |
| Yield Strength | 250-300 MPa |
| Elongation | ≥40% (typically 40-60%) |
| Reduction of Area | ≥60% |
| Hardness | 85-95 HRB (180-220 HV) |
| Elastic Modulus | ~193 GPa |
| Magnetism | Non-magnetic or weakly magnetic (permeability <1.02) |
| Density | ~7.93 g/cm³ |
3. Production Process
Melting & Casting: Electric arc furnace (EAF) melting → AOD/VOD refining (for low carbon and impurities) → continuous casting into billets.
Hot Rolling: Billet heating → controlled rolling → controlled cooling to achieve grain size ASTM 7-9.
Pickling & Coating: Remove oxide scales → apply oxalate/resin coating for lubrication in cold working.
Cold Drawing: Multi-pass cold drawing to target diameter (0.15-16mm).
Annealing: Bright annealing under protective atmosphere to restore ductility, reduce hardness, and eliminate work hardening.
Finishing & Packaging: Surface treatment (bright/matte) → coil packaging.
4. Key Characteristics
Excellent Cold Heading Performance: High ductility and low work hardening rate, suitable for complex fastener forming without cracking.
Superior Corrosion Resistance: Passes 48+ hours salt spray test; up to 500+ hours after passivation, resistant to atmospheric and mild chemical corrosion.
Low Magnetism: Retains weak magnetism after cold working, ideal for electronic and precision devices.
Good Surface Quality: Smooth surface with protective coating, reducing die friction and extending tool life.
Eco-friendly: Lead-free, meets EU environmental standards (RoHS, REACH).
5. ApplicationsFasteners:
Primary use for screws, nuts, bolts, rivets, and nails via cold heading.
Industries: Automotive, electronics, construction, machinery, and household appliances.
Precision Parts: Electronic components, medical devices, and magnetic-sensitive assemblies.
Corrosive Environments: Outdoor structures, marine hardware, and chemical equipment parts.
