S-91251A566 1/4"-20 x 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.
• Superior corrosion resistance from the black-oxide coating extends service life in demanding industrial environments.
• Precise Class 3A thread fit provides secure, vibration-resistant connections for critical assemblies.
• Partially threaded design allows for controlled clamping force and easier alignment in complex applications.
• High hardness rating (Rockwell C37) maintains thread integrity and drive socket durability through repeated use.
• Standard hex socket drive enables easy installation with common tools in confined spaces.
• Full regulatory compliance with RoHS 3 and REACH ensures environmental and safety standards are met for global supply chains.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw delivers critical reliability for heavy machinery, automotive systems, and precision equipment where high tensile strength and corrosion resistance are paramount. The UNC coarse thread design facilitates quicker assembly and reduces cross-threading risks in production lines, while the partially threaded shank concentrates clamping force exactly where needed. Engineered to ASTM A574 specifications, these screws maintain dimensional stability under extreme loads, making them ideal for structural frameworks, motor mounts, and industrial automation components that demand consistent performance and long-term durability.

Specification Summary & Compliance

Manufactured to exact Class 3A thread fit tolerances with UNC coarse threads (1/4"-20) and a minimum thread length of 1". Complies with ASTM A574 manufacturing standards for socket head cap screws. Meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use in industrial and international markets.