S-91257A751 1/2"-20 x 3" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Maximum Load-Bearing Capacity – Grade 8 classification and 150,000 psi tensile strength ensure reliable performance in high-stress industrial environments.
• Enhanced Corrosion Resistance – Zinc yellow-chromate plating provides durable protection against rust and environmental degradation.
• Precise Thread Engagement – Class 2A thread fit and UNF fine threading offer superior vibration resistance and secure fastening.
• Optimized Torque Application – External hex drive and 3/4" head width allow for easy installation with standard tools.
• Partial Threading Design – Combines unthreaded shank strength with threaded section grip for versatile load distribution.
• Industry Compliance Assurance – Meets ASME B18.2.1 and SAE J429 standards for consistent quality and interchangeability.
• Environmental Regulation Compliance – RoHS 3 and REACH compliant for safe use in regulated industries.

Professional Applications & Engineering Value

Engineered for heavy-duty industrial applications, these Grade 8 hex head screws address critical challenges in machinery assembly, structural framing, and equipment manufacturing. The UNF fine thread spacing maintains clamping force under vibration, while the Rockwell C33 hardness prevents thread deformation during repeated torque cycles. The zinc yellow-chromate finish extends service life in humid or corrosive environments, making these partially threaded fasteners ideal for automotive, construction, and manufacturing sectors where 150,000 psi tensile strength and regulatory compliance are non-negotiable.

Specification Summary & Compliance

Manufactured to Class 2A thread fit tolerances with 1/2"-20 UNF fine threading and 3" length. Complies with ASME B18.2.1 dimensional standards and SAE J429 material specifications. Meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental directives for hazardous substance restrictions.