S-91781A557 1/4"-28 x 1/2" ASME B18.6.3 Stainless Steel Slotted Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel construction and passivated finish, ideal for harsh industrial environments.
• High tensile strength of 80,000 psi ensures reliable, long-lasting fastening under demanding loads.
• Precision Class 2A thread fit provides smooth assembly and secure engagement in fine-threaded applications.
• Standard 82° countersink angle allows for a flush, low-profile installation in countersunk holes.
• Full threading along the 1/2" length offers maximum grip and holding power across the entire fastener.
• Rockwell B80 hardness enhances durability and resistance to wear during installation and use.
• Compliance with ASME B18.6.3, RoHS 3, and REACH guarantees quality, safety, and environmental standards are met.

Professional Applications & Engineering Value

This 1/4"-28 UNF flat head slotted screw is engineered to address critical challenges in industrial assembly, where corrosion resistance and precise fit are paramount. The 18-8 stainless steel material, combined with a passivated finish, effectively prevents rust and degradation in moist or chemically aggressive settings, reducing maintenance needs. Its fine UNF threading and Class 2A fit ensure tight, vibration-resistant connections in machinery, electronics, and automotive components, minimizing the risk of loosening. The flat head design with an 82° countersink facilitates seamless integration into surfaces, making it ideal for applications requiring a smooth finish, such as in aerospace or precision equipment. By offering high tensile strength and full threading, this screw provides reliable performance in industrial screws applications, enhancing product longevity and operational safety.

Specification Summary & Compliance

This screw features a 1/4"-28 UNF fine thread with Class 2A thread fit for precise dimensional accuracy, ensuring consistent performance in assembly. It adheres to ASME B18.6.3 manufacturing specifications, guaranteeing uniformity and reliability. Additionally, it is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming it is free from hazardous substances and safe for various industrial and consumer applications.