S-91253A113 4-40 x 3/4" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional corrosion resistance with black-oxide coating, ideal for harsh industrial environments
• High tensile strength of 130,000 psi ensures reliable performance under heavy loads
• Precise Class 3A thread fit guarantees secure fastening and vibration resistance
• Hex drive design provides superior torque transmission and prevents stripping
• 82° countersink angle allows for flush mounting in standard applications
• Full threading along 3/4" length enables maximum grip depth and adjustment flexibility
• Rockwell C39 hardness maintains structural integrity through repeated use

Professional Applications & Engineering Value

These 4-40 UNC flat head screws deliver critical performance advantages in precision assembly applications where space constraints and material compatibility are paramount. The black-oxide alloy steel construction provides superior corrosion protection without compromising the 130,000 psi tensile strength, making them ideal for automotive components, electronic enclosures, and machinery where exposure to oils and moisture is common. The hex drive design ensures secure installation in high-torque scenarios, while the Class 3A thread fit maintains precise tolerances for vibration-resistant connections. The 82° countersink profile facilitates seamless flush mounting in standardized fixtures, eliminating protrusions in sensitive applications.

Specification Summary & Compliance

Manufactured to exacting Class 3A thread fit standards with UNC coarse threading and right-hand orientation. Fully compliant with ASME B18.3 dimensional specifications and ASTM F835 material standards. Meets environmental regulations including RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliance for restricted substance control. The black-oxide surface treatment enhances durability while maintaining precise 0.112" thread diameter and 3/4" length tolerances.