S-91251A640 3/8"-16 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.
• Superior corrosion resistance from the black-oxide finish prolongs service life in harsh industrial environments, minimizing maintenance needs.
• Precise Class 3A thread fit provides tighter tolerances for secure, vibration-resistant connections in critical assemblies.
• High hardness (Rockwell C37) offers excellent wear resistance, maintaining thread integrity through repeated use.
• Coarse UNC threads enable quicker installation and reduced cross-threading risks, boosting assembly efficiency.
• Partially threaded design allows for controlled clamping force, ideal for applications requiring precise joint security.
• Compliance with ASTM A574, RoHS 3, and REACH ensures material consistency and environmental safety for global supply chains.

Professional Applications & Engineering Value

Engineered for demanding environments, these black-oxide alloy steel socket head cap screws address common industrial challenges like vibration loosening and corrosion. The 3/8"-16 UNC coarse threads with a Class 3A fit deliver superior engagement in metals and composites, preventing slippage in heavy machinery, automotive systems, and construction equipment. The hex drive design (5/16" drive size) allows high-torque installation with standard tools, streamlining assembly in confined spaces. Combined with 170,000 psi tensile strength and Rockwell C37 hardness, these fasteners withstand extreme loads and abrasion, reducing downtime in manufacturing, aerospace, and robotics applications where reliability is critical.

Specification Summary & Compliance

This screw features a 3/8"-16 UNC coarse thread with Class 3A precision fit and a minimum thread length of 1 1/4" on a partially threaded rod. Dimensions include a 4" length, 9/16" head diameter, and 3/8" head height. It conforms to ASTM A574 for material and manufacturing standards, ensuring consistent quality. The product is verified as RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, meeting international environmental and safety regulations for hazardous substances.