S-91253A304 1/4"-28 x 1/4" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength (130,000 psi) ensures reliable performance in high-stress industrial applications
• Class 3A thread fit precision provides superior engagement and vibration resistance in critical assemblies
• Black-oxide alloy steel construction offers enhanced corrosion resistance for extended service life
• 82° undercut flat head design enables flush mounting while maximizing head strength
• Hex drive compatibility (5/32") allows for secure installation with standard industrial tools
• Fine UNF threading (1/4"-28) delivers superior holding power in thin materials and precision components
• Full threading configuration ensures consistent fastening performance along the entire screw length

Professional Applications & Engineering Value

These black-oxide alloy steel flat head screws with Class 3A UNF fine threading are engineered to address critical fastening challenges in precision manufacturing and heavy-duty applications. The 82° countersink angle combined with the undercut flat head profile creates optimal flush mounting capabilities while distributing clamp load efficiently. The Rockwell C39 hardness rating and 130,000 psi tensile strength make these screws ideal for machinery, automotive components, and industrial equipment where vibration resistance and long-term reliability are paramount. The fully threaded right-hand design ensures maximum engagement in both metallic and high-density composite materials, providing engineers with a versatile solution for demanding assembly requirements.

Specification Summary & Compliance

Manufactured to exact Class 3A thread fit tolerances with 1/4"-28 UNF fine threading and compliant with ASTM F835 specifications. These screws feature Rockwell C39 hardness and meet RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental compliance standards, ensuring they are suitable for global industrial applications and regulated environments.