S-91251A029 1/2"-20 x 4" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 PSI for reliable performance in high-stress applications, reducing the risk of fastener failure.
• Precision Class 3A thread fit ensures tight, secure connections with minimal backlash, ideal for critical assembly operations.
• Black-oxide finish on alloy steel provides enhanced corrosion resistance and a durable, non-galling surface for extended service life.
• 3/8" hex drive design allows for high torque application and easy installation in confined spaces with standard tools.
• Partially threaded shank offers optimal grip and clamping force where full threading isn't required, improving joint stability.
• Fine thread spacing (UNRF) delivers superior vibration resistance and finer adjustment capabilities in dynamic environments.
• Compliance with ASTM A574, RoHS 3, and REACH guarantees material consistency, environmental safety, and suitability for regulated industries.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address common industrial challenges such as vibration loosening, corrosion, and high-load demands. The Class 3A thread fit and UNRF fine thread design provide exceptional clamp load retention and precision alignment in machinery, automotive, and heavy equipment assemblies. The high tensile strength and Rockwell C37 hardness ensure durability under cyclic stresses, while the black-oxide surface treatment resists rust and wear in harsh operating conditions. Ideal for industrial socket screw applications requiring reliable, high-strength fastening solutions that meet stringent quality and compliance standards.

Specification Summary & Compliance

This socket head cap screw features a 1/2"-20 UNRF thread with Class 3A fit for precise dimensional accuracy, and a partially threaded rod type. It is manufactured in accordance with ASTM A574 specifications, ensuring consistent mechanical properties. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming its suitability for use in environmentally conscious and regulated industrial markets.