S-91773A539 1/4"-20 x 5/8" ASME B18.6.3 Stainless Steel Round Head Phillips Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel construction and passivated finish for extended service life in harsh environments
• Exceptional mechanical strength delivering 100,000 psi tensile strength and Rockwell B100 hardness for reliable load-bearing performance
• Precision thread engagement with Class 2A UNC coarse threads ensuring consistent, vibration-resistant fastening connections
• Optimized drive efficiency featuring No. 3 Phillips drive for secure tool engagement and reduced cam-out during installation
• Full-threaded design providing maximum grip length and uniform stress distribution across the entire fastener
• Regulatory compliance assurance meeting ASME B18.6.3 specifications while being RoHS 3 and REACH compliant
• Versatile rounded head profile offering smooth surface transition and reduced risk of snagging in assembled applications

Professional Applications & Engineering Value

Engineered for demanding industrial environments, these 18-8 stainless steel rounded head screws combine material excellence with precision manufacturing to address critical assembly challenges. The passivated surface treatment creates an enhanced protective oxide layer that significantly improves corrosion resistance in moisture-prone applications, while the UNC coarse thread configuration ensures rapid installation and superior vibration resistance in machinery, equipment manufacturing, and structural assemblies. The fully threaded design maximizes engagement surface area, distributing clamping forces evenly to prevent joint failure under dynamic loads. These Phillips drive screws are particularly valuable in applications requiring repeated maintenance access, where their combination of 100,000 psi tensile strength and chemical resistance ensures long-term reliability without compromising disassembly efficiency.

Specification Summary & Compliance

This 1/4"-20 x 5/8" rounded head screw features precision Class 2A thread fit tolerances with UNC coarse thread spacing (20 TPI) and right-hand threading. Manufacturing complies with ASME B18.6.3 standards for dimensional accuracy and mechanical properties. The fastener is fully compliant with RoHS 3 (2015/863/EU) restrictions on hazardous substances and meets REACH (EC 1907/2006) requirements for chemical safety, ensuring environmental regulatory adherence for industrial and commercial applications worldwide.