S-91257A755 1/2"-20 x 5" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional Tensile Strength: With 150,000 psi tensile strength, this screw provides superior load-bearing capacity, reducing the risk of failure in high-stress applications.
• Enhanced Corrosion Resistance: Zinc yellow-chromate plating offers reliable protection against rust and environmental degradation, extending service life in harsh conditions.
• High Hardness for Durability: Rockwell C33 hardness ensures the fastener maintains its integrity under heavy loads and repeated use, minimizing wear and deformation.
• Precise Thread Fit: Class 2A thread fit with UNF fine threading allows for smooth assembly and secure fastening, reducing the chance of cross-threading and improving joint reliability.
• Industry Standard Compliance: Meets ASME B18.2.1 and SAE J429 specifications, ensuring consistent quality and compatibility with existing industrial systems.
• Optimized for Heavy-Duty Use: The partially threaded design and external hex drive enable easy installation and removal with standard tools, saving time in maintenance and assembly.
• Environmental and Safety Compliance: RoHS 3 and REACH compliant, making it suitable for regulated industries without hazardous substance concerns.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to address critical challenges in heavy machinery, construction, and automotive sectors where high tensile strength and corrosion resistance are paramount. The steel material combined with zinc yellow-chromate plating ensures long-term durability in corrosive environments, while the UNF fine thread and Class 2A fit provide precise engagement to prevent loosening under vibration. Its partially threaded design allows for controlled clamping force, making it ideal for bolted joints in structural applications. By meeting ASME B18.2.1 standards, it guarantees reliability in industrial fastening systems, reducing downtime and maintenance costs for engineers and procurement specialists.

Specification Summary & Compliance

This fastener adheres to precise dimensional tolerances, including Class 2A thread fit and UNF fine threading with a thread size of 1/2"-20. It is manufactured in accordance with ASME B18.2.1 and SAE J429 specifications, ensuring consistent performance. Compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) confirms it is free from restricted substances, making it suitable for global industrial use without regulatory concerns.