S-91253A477 1/4"-20 x 5" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional Tensile Strength: Withstands up to 130,000 psi for reliable performance in high-stress industrial applications.
• Superior Corrosion Resistance: Black-oxide finish on alloy steel provides enhanced durability against rust and environmental wear.
• Precision Thread Fit: Class 3A UNC coarse threads ensure tight, secure fastening with minimal risk of loosening.
• Optimized Load Distribution: Flat head design with 82° countersink angle allows for flush mounting and even pressure dispersion.
• Easy Installation: Hex drive (5/32") enables quick, tool-friendly assembly without slipping.
• Partial Threading Design: Maximizes grip strength on thicker materials while reducing overall weight.
• High Hardness Rating: Rockwell C39 hardness ensures long-term wear resistance and thread integrity.

Professional Applications & Engineering Value

This 1/4-20 flat head screw is engineered to address common industrial fastening challenges, such as vibration-induced loosening and material fatigue. The black-oxide alloy steel construction offers superior corrosion resistance, making it ideal for harsh environments like manufacturing equipment, automotive assemblies, and structural frameworks. Its UNC coarse threading and Class 3A fit provide excellent holding power in metals and composites, while the partial threading reduces the risk of cross-threading during installation. The flat head profile ensures a seamless finish in countersunk applications, enhancing both safety and aesthetics. These features make it a reliable choice for heavy-duty fastening where precision and durability are critical.

Specification Summary & Compliance

This screw adheres to Class 3A thread fit for precise dimensional accuracy and meets ASME B18.3 and ASTM F835 manufacturing standards. It is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and material reliability. The product features a 1/4"-20 UNC coarse thread with a minimum thread length of 1 inch and a standard 82° countersink angle, designed for consistent performance in industrial settings.