Zeron Fastners
SS 347 Socket Head Cap Screws (Allen Bolts)
SS 347 Socket Head Cap Screws, commonly referred to as **Allen Bolts** due to their internal hexagonal drive, are high-strength mechanical fasteners known for their clean, cylindrical heads and superior clamping force. This grade of screw utilizes **Niobium-stabilized** austenitic stainless steel, which is critical for applications involving high service temperatures, particularly in the range of **425°C to 816°C**. The Niobium content prevents the formation of chromium carbides, effectively eliminating the risk of **intergranular corrosion** post-welding or heat exposure. Zeron Fasteners supplies these premium screws, ensuring reliable, high-integrity connections in demanding industries like aerospace, chemical processing equipment, and pressure vessel manufacturing.
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SS 347 Socket Head Cap Screws Chemical Composition
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.08 max |
| Manganese (Mn) | 2.00 max |
| Phosphorus (P) | 0.045 max |
| Sulfur (S) | 0.030 max |
| Silicon (Si) | 1.00 max |
| Chromium (Cr) | 17.00 – 19.00 |
| Nickel (Ni) | 9.00 – 13.00 |
| Niobium (Nb) + Tantalum (Ta) | 10 x C – 1.00 |
Note: The combined Niobium and Tantalum content must be ten times the Carbon content minimum, up to a maximum of 1.00%.
SS 347 Socket Head Cap Screws Mechanical Properties
| Property | Value (Typical, Class 1) |
|---|---|
| Tensile Strength | 515 MPa |
| Yield Strength (0.2% Offset) | 205 MPa |
| Elongation | 30% |
| Rockwell Hardness (HRB) | 95 max |
| Proof Load Stress | 205 MPa |