S-91251A149 4-40 x 1 1/2" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Enhanced Durability and Corrosion Resistance with black-oxide coating on alloy steel, ideal for harsh industrial environments.
• High Tensile Strength of 170,000 psi ensures reliable performance under heavy loads and stress conditions.
• Precision Class 3A Thread Fit provides superior thread engagement and vibration resistance in critical assemblies.
• Hex Socket Drive Design allows for easy installation with standard 3/32" hex tools, reducing assembly time and tool slip.
• Partially Threaded 1-1/2" Length with 3/4" minimum thread engagement offers flexibility for varied clamping and fastening needs.
• Compliance with ASTM A574 guarantees consistent quality and mechanical properties for industrial applications.
• RoHS 3 and REACH Compliant ensures environmental safety and regulatory adherence in global markets.

Professional Applications & Engineering Value

This Black-Oxide Alloy Steel Socket Head Cap Screw with 4-40 UNC coarse threads is engineered to address common industrial challenges such as vibration loosening and material fatigue. The high tensile strength of 170,000 psi and Rockwell C37 hardness provide exceptional resistance to shear and tensile forces, making it suitable for heavy-duty machinery, automotive assemblies, and precision equipment. The black-oxide surface treatment enhances corrosion resistance, extending service life in humid or corrosive environments. Its partially threaded design allows for secure fastening in applications where unthreaded shank areas are needed for alignment or shear strength, reducing the risk of thread damage and ensuring long-term reliability in industrial screws and fastener systems.

Specification Summary & Compliance

This screw features precise Class 3A thread fit and UNC coarse threads with a minimum thread length of 3/4" on a 1-1/2" overall length, ensuring accurate engagement. It conforms to ASTM A574 specifications for material and mechanical properties, and is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, supporting safe and sustainable industrial use.