S-91771A551 1/4"-20 x 2 1/4" ASME B18.6.3 Stainless Steel Phillips Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with passivated 18-8 stainless steel construction, ideal for harsh industrial environments
• High tensile strength of 80,000 psi ensures reliable fastening under significant mechanical stress
• Rockwell B80 hardness provides excellent durability and resistance to wear over time
• Standard 82° countersink angle allows for flush mounting and clean aesthetic finishes
• Partially threaded design offers optimal grip and clamping force in specific assembly applications
• Phillips No. 3 drive enables efficient installation with common tools, reducing assembly time
• Compliance with RoHS 3 and REACH ensures environmental safety and regulatory acceptance

Professional Applications & Engineering Value

These 1/4"-20 UNC flat head screws are engineered to address critical challenges in industrial assembly where corrosion resistance and structural integrity are paramount. The passivated 18-8 stainless steel material provides a protective oxide layer that significantly extends service life in moist or chemically aggressive environments, reducing maintenance costs and downtime. The coarse UNC thread and Class 2A thread fit ensure quick, secure fastening in metals, plastics, and composite materials, making them ideal for machinery, automotive components, and electrical enclosures. The partially threaded configuration allows for precise clamping without over-tightening, while the flat head with standard profile sits flush to prevent snagging and improve safety. These screws deliver consistent performance in applications demanding high tensile strength and reliability, supported by adherence to ASME B18.6.3 standards for dimensional accuracy and quality.

Specification Summary & Compliance

This screw features a 1/4"-20 UNC coarse thread with Class 2A thread fit for precise tolerance, ensuring compatibility with standard nuts and tapped holes. It is manufactured in accordance with ASME B18.6.3 specifications, guaranteeing consistent dimensions and performance. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming it is free of hazardous substances and safe for various industrial and commercial uses.