S-91771A112 4-40 x 5/8" ASME B18.6.3 Stainless Steel Phillips Flat Head Screws
Stainless Steel Phillips Flat Head Screws
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Basic Information
Head Parameters
Dimensions
Thread Parameters
Tip & Drive Parameters
Material & Strength
Temperature & Environment
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Key Features & Benefits at a Glance
- Superior corrosion resistance with passivated 18-8 stainless steel construction, ideal for harsh industrial environments
- Exceptional tensile strength of 80,000 psi ensures reliable performance under heavy loads and vibration
- Precise Class 2A thread fit provides smooth installation and secure fastening in UNC coarse thread applications
- Optimized flush mounting with standard 82° countersink angle for seamless surface integration
- Enhanced drive engagement through Phillips No. 1 drive design prevents cam-out during installation
- Full threading along the entire 5/8" length maximizes grip strength and load distribution
- Consistent hardness at Rockwell B80 maintains dimensional stability through repeated use
Professional Applications & Engineering Value
These 4-40 UNC flat head screws deliver critical performance advantages in precision assembly applications where corrosion resistance and flush surface requirements are paramount. The passivated 18-8 stainless steel construction provides excellent protection against chemical exposure and atmospheric corrosion, making these Phillips drive screws ideal for electronic enclosures, machinery panels, and marine equipment. The coarse UNC threading ensures rapid installation in softer materials while maintaining secure fastening, while the standardized 82° countersink angle guarantees proper seating in chamfered holes. With full threading along the entire 5/8" length, these screws distribute clamping force evenly, preventing material distortion in sensitive assemblies and reducing the risk of joint failure in vibrating environments.
Specification Summary & Compliance
Manufactured to exacting ASME B18.6.3 specifications with Class 2A thread fit tolerances for consistent performance. These flat head screws feature right-hand UNC coarse threads with 4-40 sizing and maintain full compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. The combination of 80,000 psi tensile strength and Rockwell B80 hardness ensures mechanical reliability across industrial applications while meeting international fastener standards.
