S-91251A375 1/2"-20 x 4 3/4" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi provides superior resistance to breaking and stripping under high-stress loads.
• Class 3A thread fit ensures tighter tolerances and more reliable, vibration-resistant assemblies compared to standard fits.
• Black-oxide finish on alloy steel offers enhanced corrosion resistance for extended service life in demanding environments.
• 3/8" hex drive design allows for high-torque installation with common tools, reducing assembly time and improving efficiency.
• Partially threaded shank provides an unthreaded portion for precise clamping and alignment in fastened joints.
• Rockwell C37 hardness delivers excellent wear resistance, maintaining thread integrity through repeated use.
• Compliance with ASTM A574, RoHS 3, and REACH guarantees material consistency and environmental safety for global industrial applications.

Professional Applications & Engineering Value

This Black-Oxide Alloy Steel Socket Head Cap Screw is engineered to address critical challenges in heavy-duty machinery, automotive, and aerospace assemblies. The 1/2"-20 UNF fine thread with Class 3A fit minimizes the risk of loosening under vibration, a common failure point in dynamic systems. The alloy steel construction and 170,000 psi tensile strength ensure reliable performance in high-load scenarios, while the black-oxide surface treatment provides essential corrosion protection without compromising dimensional accuracy. Its 3/8" hex drive facilitates secure installation in confined spaces, making it ideal for precision equipment where access is limited. This combination of material durability, thread precision, and environmental compliance delivers long-term reliability and reduced maintenance costs.

Specification Summary & Compliance

This socket head cap screw adheres to Class 3A thread fit per UNF standards, ensuring precise engagement and high fatigue resistance. Manufactured in accordance with ASTM A574 for consistent material properties and dimensional accuracy. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming the absence of restricted hazardous substances. Thread specifications include a 1/2"-20 UNF fine thread with a minimum thread length of 1 1/2" on a partially threaded rod, optimized for secure clamping applications.