Low-Carbon Steel Class 4.8 Fasteners | The Economical Choice for Furniture and Light Assembly
Class 4.8 is the entry grade of the carbon-steel fastener system, intended for light-duty work such as furniture, general brackets and trim, priced below class 8.8 and usually supplied in blue-white or yellow zinc. It looks almost identical to an 8.8 part, which is why substituting 4.8 for 8.8 is one of the most common misuses — the 4.8 head mark is easy to read, so verify marks part by part on receipt. For any load-bearing, vibrating or alternating-load joint, design at class 8.8 or above rather than saving here.
Properties & Specifications
| Property Class | 4.8 (carbon steel, low-carbon / mild steel cold-formed) |
| Tensile Strength | 400 MPa class (nominal, per the class-number rule) |
| Hardness | Below class 8.8 (22 – 32 HRC) |
| Base Material | Low-carbon steel wire (cold-headed) |
| Heat Treatment | Not required at this class |
| Typical Finish | Blue-white zinc, yellow zinc, nickel |
| Service Temperature | ≤ 80°C (electro-plated zinc limit) |
| Relative Price | Below class 8.8 (8.8 is the baseline 1.0 for high-strength grades) |
Material Advantages
Lowest-cost standard-part route, suited to high-volume non-load-bearing assembly
High cold-heading yield makes thin heads and large flange washers easier to form at this class
Decorative finishes are available: blue-white zinc, yellow zinc and nickel
Good low-carbon toughness means hand tightening on site rarely produces brittle failures
Grading the drawing lets load-bearing and cosmetic parts each be priced on their own basis
Applications
Furniture and display-case assembly
General brackets, cable trunking and tray fixing
Appliance enclosures and panel screws
Trim, nameplates and cosmetic fixings
Light sheet-metal and plastic-part joints
Never for: structural load paths, vibration, alternating load or safety parts
Grade Selection
| Class / Grade | Service temperature | Notes |
|---|---|---|
| 4.8 | ≤ 80°C（电镀锌） | Light duty: furniture and general brackets |
| 5.8 / 6.8 | ≤ 80°C（电镀锌） | Intermediate classes; the legacy reference set carries no measured values — confirm against the design file |
| 8.8 | ≤ 80°C（电镀锌）/ ≤ 250°C（热浸锌） | The lowest class we recommend for load-bearing and vibrating joints, at 800 MPa |
| A2-70 | 含氯水环境 > 60°C 有应力腐蚀风险 | The alternative where appearance and corrosion resistance lead |
Frequently Asked Questions
Read the head mark. Class 8.8 parts carry an 8.8 stamp while 4.8 parts carry 4.8 (very small sizes are sometimes unstamped). Appearance and dimensions are practically identical while the price can differ several-fold, which is exactly why passing 4.8 off as 8.8 is a listed classic misuse. Check marks part by part on receipt and require a batch mill certificate.
Yes. That is precisely the duty class 4.8 is set for — lowest cost, high cold-heading yield and decorative plating options. As long as the joint carries no structural load and sees no vibration or alternating load, there is no reason to pay for strength.
It is processable but makes little engineering sense: hot-dip galvanising exists for long-life corrosion protection on structures (1000 h+ salt spray), and 4.8 is simply not strong enough for those applications. Use 8.8 hot-dip galvanised for steelwork, and blue-white or yellow zinc for indoor light-duty parts.
Get Grade Selection & Quotation
Submit your duty parameters (temperature, pressure, media, speed) — engineers reply with grade selection and quotation within 24 hours.