S-91255A589 5/16"-18 x 2 1/4" ASTM F835 Steel Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Exceptional Durability: Black-oxide coating on alloy steel provides superior corrosion resistance, extending service life in demanding industrial environments.
• High Tensile Strength: Rated at 120,000 psi tensile strength and Rockwell C39 hardness for reliable performance in high-stress applications.
• Secure Fastening: Class 3A thread fit ensures precise, tight connections with minimal risk of loosening under vibration.
• Efficient Installation: Hex drive (3/16") allows for high-torque application with standard tools, speeding up assembly processes.
• Full Thread Engagement: Fully threaded design maximizes grip strength and distributes load evenly across the entire fastener length.
• Wide Compatibility: 5/16"-18 UNC coarse threads provide excellent engagement in a variety of materials and applications.
• Regulatory Compliance: Meets ASME B18.3 and ASTM F835 specifications while being RoHS 3 and REACH compliant for global use.

Professional Applications & Engineering Value

Engineered for heavy-duty industrial applications, these black-oxide alloy steel rounded head screws deliver exceptional performance where reliability is critical. The Class 3A thread fit maintains precise tolerances for vibration-resistant connections in machinery, equipment frames, and structural assemblies. The coarse UNC threading provides superior holding power in both metallic and non-metallic materials, while the button head profile offers a low-profile finish that reduces snagging hazards. The combination of 120,000 psi tensile strength and Rockwell C39 hardness ensures these fasteners withstand extreme mechanical stresses without compromising integrity, making them ideal for automotive, manufacturing, and construction applications where failure is not an option.

Specification Summary & Compliance

This 5/16"-18 UNC screw features Class 3A thread fit precision manufacturing with full threading along its 2-1/4" length. The product complies with ASME B18.3 and ASTM F835 specifications for dimensional accuracy and performance standards. Environmental compliance includes RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) requirements, ensuring safe use in regulated markets. The right-hand coarse threading and standardized hex drive interface provide consistent, reliable performance across industrial applications.