S-91251A303 3/4"-16 x 5" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional Tensile Strength – With 170,000 psi tensile strength, this screw reliably handles extreme loads and high-stress applications, reducing the risk of fastener failure.
• Superior Thread Precision – Class 3A UNRF fine threads provide a tighter, more secure fit with less vibration loosening, ensuring long-term joint integrity.
• Enhanced Corrosion Resistance – The black-oxide finish on alloy steel offers improved protection against rust and wear in harsh industrial environments.
• High Hardness for Durability – Rockwell C37 hardness ensures the screw maintains its shape and strength under repeated use and high torque.
• Optimized for High-Torque Applications – The 5/8" hex drive and standard socket head allow for easy installation with common tools, even in confined spaces.
• Reliable Partial Threading – The partially threaded design provides unthreaded shank strength where needed, improving clamp load distribution.
• Broad Industrial Compliance – Meets ASTM A574, RoHS 3, and REACH standards, ensuring material quality and environmental safety for global supply chains.

Professional Applications & Engineering Value

This Black-Oxide Alloy Steel Socket Head Cap Screw is engineered for demanding applications where failure is not an option. Its UNRF fine thread (Class 3A) delivers superior resistance to vibration and dynamic loads, making it ideal for heavy machinery, automotive assemblies, and precision equipment. The black-oxide surface treatment enhances corrosion resistance without sacrificing the core strength provided by the alloy steel material. With a 5-inch length and partially threaded design, it offers optimal grip and stress distribution in structural joints. These screws are commonly specified in aerospace, manufacturing, and construction projects requiring high tensile strength (170,000 psi) and reliable performance under cyclic loading conditions.

Specification Summary & Compliance

This socket head cap screw features a 3/4"-16 UNRF fine thread with Class 3A fit, ensuring high precision and minimal tolerance deviation. It is manufactured in accordance with ASTM A574 specifications for alloy steel socket head cap screws. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming its adherence to restricted substance guidelines and environmental safety standards.