S-91251A389 5/16"-24 x 1 3/4" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi ensures reliable performance in high-stress applications, reducing the risk of fastener failure.
• Superior corrosion resistance from the black-oxide finish on alloy steel extends service life in harsh industrial environments.
• Precise Class 3A thread fit provides tighter tolerances for secure, vibration-resistant assemblies with minimal backlash.
• Fine UNF threading offers improved load distribution and better sealing capabilities compared to coarse threads.
• High hardness (Rockwell C37) enhances wear resistance, maintaining thread integrity through repeated use.
• 1/4" hex drive socket head allows for easy installation with standard tools, even in confined spaces.
• Partial threading design enables optimal clamping force control for specific joint requirements.

Professional Applications & Engineering Value

Engineered for demanding industrial applications, these black-oxide alloy steel socket head cap screws deliver exceptional performance in machinery, automotive, and heavy equipment assemblies. The combination of 170,000 psi tensile strength and Rockwell C37 hardness ensures reliable operation under extreme loads and vibrations. The fine UNF threading with Class 3A fit provides superior engagement and resistance to loosening in precision applications. The black-oxide surface treatment offers enhanced corrosion protection without sacrificing dimensional accuracy, making these fasteners ideal for environments where moisture and chemicals are present. The 1/4" hex drive facilitates quick installation while the partially threaded design allows for precise clamping force distribution in critical connections.

Specification Summary & Compliance

These socket head cap screws feature 5/16"-24 UNF fine threads with Class 3A thread fit for precision applications, measuring 1 3/4" in length with a minimum thread length of 1 1/8". Manufactured to ASTM A574 specifications for high-strength socket head cap screws, they comply with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. The right-hand thread direction and standard socket head profile ensure compatibility with industry-standard installation tools and procedures.