S-91251A826 2-56 x 7/8" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi ensures reliable performance under high-stress conditions, reducing the risk of fastener failure in demanding applications.
• Superior corrosion resistance from the black-oxide finish extends service life in harsh industrial environments, minimizing maintenance and replacement costs.
• Precise Class 3A thread fit guarantees secure, vibration-resistant connections, enhancing assembly integrity and reducing loosening over time.
• High hardness rating (Rockwell C37) provides excellent wear resistance, maintaining thread integrity through repeated installations and removals.
• Partially threaded design with a minimum 5/8" thread length allows for optimal grip and clamping force in specific assembly configurations.
• Standard hex drive (5/64") enables easy installation with common tools, streamlining assembly processes and reducing labor time.
• Compliance with ASTM A574, RoHS 3, and REACH ensures adherence to industry standards and environmental regulations, supporting responsible sourcing and usage.

Professional Applications & Engineering Value

These black-oxide alloy steel socket head cap screws are engineered to address critical challenges in industrial fastening, such as vibration-induced loosening and environmental degradation. The 2-56 UNC coarse threads and Class 3A fit provide superior holding power in materials where fine threads might strip, making them ideal for machinery, automotive assemblies, and precision equipment. The partially threaded rod type allows for targeted clamping without unnecessary thread engagement, reducing stress concentrations. With a Rockwell C37 hardness and 170,000 psi tensile strength, they withstand dynamic loads and repetitive use, ensuring long-term reliability in applications like aerospace components, electronic enclosures, and heavy-duty manufacturing systems where corrosion resistance and dimensional stability are paramount.

Specification Summary & Compliance

This product features precise inch system measurements with a 2-56 UNC coarse thread and Class 3A thread fit for tight tolerances. It complies with ASTM A574 specifications for alloy steel socket head cap screws, ensuring consistent manufacturing quality. Additionally, it meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliance standards, supporting environmental safety and regulatory adherence in global supply chains.