S-91251A321 1"-14 x 4" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi ensures reliable performance under extreme loads, minimizing the risk of fastener failure in critical applications.
• Superior thread precision with a Class 3A fit provides tighter tolerances and improved vibration resistance, leading to more secure and durable assemblies.
• Corrosion-resistant Black-Oxide finish on alloy steel enhances durability and provides a protective layer against rust in demanding industrial environments.
• High hardness rating of Rockwell C37 offers excellent wear resistance, extending the screw's service life and reducing replacement frequency.
• Partially threaded design allows for precise clamping force control and is ideal for applications where unthreaded shank strength is required.
• Fine UNRF threads enable finer adjustments and better load distribution compared to coarse threads, improving joint integrity.
• 3/4" hex drive socket head facilitates easy installation and high torque application with standard tools, reducing assembly time and effort.

Professional Applications & Engineering Value

This Black-Oxide Alloy Steel Socket Head Cap Screw is engineered to address common industrial challenges such as joint loosening under vibration and corrosion in harsh environments. The 1"-14 UNRF fine thread with Class 3A fit ensures precise engagement and superior clamp load retention, making it ideal for heavy machinery, automotive assemblies, and precision equipment where reliability is critical. The partially threaded rod type provides enhanced shear strength in the unthreaded portion, reducing stress concentration. Combined with high tensile strength and Rockwell C37 hardness, it delivers long-term performance in high-stress applications, minimizing maintenance downtime and improving operational safety.

Specification Summary & Compliance

This screw features a 1"-14 UNRF fine thread with Class 3A thread fit for high precision, a 4" length with minimum thread length of 2 1/2", and partially threaded design. It meets ASTM A574 specification for high-strength alloy steel socket head cap screws, ensuring consistent quality and performance. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, confirming its safety for use in various industrial sectors without hazardous substance restrictions.