S-91251A808 5/8"-11 x 3 1/2" 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 extends service life in harsh industrial environments, minimizing maintenance needs.
• Precise Class 3A thread fit provides consistent engagement and vibration resistance, enhancing assembly integrity.
• High hardness (Rockwell C37) offers excellent wear resistance, maintaining thread integrity through repeated use.
• Coarse UNRC threads allow for quicker installation and better performance in materials prone to galling or debris.
• 1/2" hex drive design enables high torque application with standard tools, speeding up assembly processes.
• Compliance with ASTM A574, RoHS 3, and REACH ensures material consistency and environmental safety for global supply chains.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address critical fastening challenges in heavy machinery, automotive, and construction sectors. The partially threaded design with coarse UNRC threads prevents loosening under dynamic loads, while the high tensile strength and Rockwell C37 hardness resist deformation in high-pressure joints. The black-oxide surface treatment provides a durable barrier against moisture and chemicals, making it ideal for outdoor or corrosive environments. By combining Class 3A thread precision with robust material properties, these screws deliver reliable clamping force and extended service life, reducing downtime and replacement costs in industrial assemblies.

Specification Summary & Compliance

This screw features a 5/8"-11 UNRC coarse thread with Class 3A fit, ensuring tight tolerances per ANSI standards. It meets ASTM A574 specifications for alloy steel socket head cap screws, guaranteeing material and manufacturing consistency. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming the absence of restricted hazardous substances. Dimensions include a 3 1/2" length with 1 3/4" minimum thread length and 1/2" hex drive for standardized tool compatibility.