S-91500A538 1/4"-20 x 5/8" ASME B18.6.3 Stainless Steel Phillips Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional corrosion resistance with 316 stainless steel construction, ideal for harsh chemical and marine environments
• Superior mechanical strength with 70,000 psi tensile strength and Rockwell B80 hardness for reliable load-bearing performance
• Precision thread engagement with Class 2A UNC coarse threads ensuring secure fastening and vibration resistance
• Enhanced surface durability through passivated finish that increases corrosion protection and extends service life
• Optimized flush mounting with standard 82° countersink angle and flat head design for smooth surface integration
• Efficient installation with Phillips No. 3 drive providing positive torque control and reduced cam-out risk
• Full-threaded design delivering maximum grip length and uniform stress distribution along the entire fastener

Professional Applications & Engineering Value

These 316 stainless steel flat head screws deliver critical performance advantages in demanding industrial settings where corrosion resistance and structural integrity are paramount. The combination of passivated finish and marine-grade 316 stainless steel provides exceptional protection against chloride-induced stress corrosion cracking, making them ideal for chemical processing equipment, marine hardware, and food processing applications. The UNC coarse thread configuration ensures rapid installation and reliable performance in materials where fine threads might strip or fail. With full threading along the 5/8" length, these Phillips drive screws distribute clamping forces evenly, preventing joint relaxation in high-vibration environments while maintaining the sleek profile required for flush-mounted applications.

Specification Summary & Compliance

Manufactured to exacting ASME B18.6.3 specifications with Class 2A thread fit tolerances ensuring consistent performance and interchangeability. The 1/4"-20 UNC coarse thread pattern provides optimal engagement in various materials. Compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations confirms environmental responsibility and material safety. The 82° countersink angle meets industry standards for flat head applications, while the Phillips No. 3 drive ensures compatibility with standard installation tools.