S-91251A193 8-32 x 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.
• Precision Class 3A thread fit provides superior engagement and vibration resistance, minimizing loosening in dynamic environments.
• Black-oxide coating on alloy steel offers enhanced corrosion resistance, extending service life in harsh industrial conditions.
• Hex socket drive design allows for high-torque installation with secure tool engagement, preventing stripping and improving assembly efficiency.
• Coarse UNC threads enable quick assembly and disassembly, saving time in maintenance and production cycles.
• Partially threaded shank provides unthreaded grip length for precise clamping force distribution without damaging materials.
• Compliance with ASTM A574, RoHS 3, and REACH ensures material consistency, environmental safety, and global regulatory acceptance.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address common industrial challenges such as vibration-induced loosening and corrosion in demanding settings. The 8-32 UNC coarse thread with a Class 3A fit delivers precise alignment and robust holding power, ideal for machinery, automotive assemblies, and heavy equipment where reliability is critical. The hex drive and standard socket head profile facilitate easy access in confined spaces, while the high tensile strength and Rockwell C37 hardness prevent deformation under load. Its partially threaded design ensures optimal stress distribution, reducing the risk of thread galling and improving joint integrity in structural applications.

Specification Summary & Compliance

This screw features a 4" length with a minimum thread length of 7/8", UNC coarse threads, and Class 3A thread fit for high precision. It meets ASTM A574 specifications for alloy steel socket head cap screws, ensuring consistent manufacturing quality. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, guaranteeing adherence to environmental and safety standards for industrial use.