S-91257A549 1/4"-20 x 1 5/8" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capacity with 150,000 psi tensile strength and Rockwell C33 hardness for reliable performance in high-stress applications
• Superior corrosion resistance through zinc yellow-chromate plating that protects against rust in demanding industrial environments
• Optimized thread engagement with UNC coarse threads and Class 2A fit ensuring secure fastening and vibration resistance
• Heavy-duty construction meeting Grade 8 specifications for maximum reliability in critical assemblies
• Easy installation and removal with standard external hex drive design compatible with common tools
• Versatile partial threading providing both threaded engagement and smooth shank for precise clamping control
• Industry compliance assurance with ASME B18.2.1 and SAE J429 standards for consistent quality and interchangeability

Professional Applications & Engineering Value

These Grade 8 hex head screws deliver exceptional engineering value in heavy machinery, construction equipment, and industrial assemblies where high tensile strength and reliable clamping force are critical. The steel construction with Rockwell C33 hardness ensures durability under extreme loads, while the zinc yellow-chromate plating provides superior corrosion protection in harsh environments. The 1/4"-20 UNC coarse thread configuration offers excellent engagement in various materials, and the partial threading design allows for precise load distribution. These heavy-duty screws solve common industrial fastening challenges by combining maximum strength with corrosion resistance, making them ideal for structural applications, equipment manufacturing, and maintenance operations requiring ASME B18.2.1/SAE J429 certified components.

Specification Summary & Compliance

This Grade 8 hex head screw features precise Class 2A thread fit with 1/4"-20 UNC coarse thread specifications and 1-5/8" length with 3/4" minimum thread length. Manufactured to exacting ASME B18.2.1 and SAE J429 standards, these fasteners ensure dimensional accuracy and mechanical properties for industrial applications. The external hex drive and inch system measurements provide compatibility with standard tools and existing assemblies. Compliance with industry specifications guarantees consistent performance and interchangeability across applications requiring high-strength fastening solutions.