5/8"-11 L9 Hex Head Cap Screw – Coarse Thread Alloy Steel Zinc Yellow CR+3 (Made in U.S.A.)

5/8"-11 L9 Hex Head Cap Screw – Coarse Thread Alloy Steel Zinc Yellow CR+3 (Made in U.S.A.)

Our 5/8"-11 L9 Hex Head Cap Screws represent the pinnacle of strength and durability, making them ideal for the most demanding applications. Manufactured in the USA from premium alloy steel, these fasteners offer exceptional performance and reliability, featuring an impressive tensile strength of 180,000 PSI. Designed for extreme conditions, these screws are perfect for heavy-duty industries and projects where secure fastening is critical.

Why Choose L9 Hex Head Cap Screws?

L9 fasteners are SAE’s highest-grade hex cap screws, designed specifically for applications where maximum strength and durability are essential. Recognized by nine radial lines and an "L9" marking on the head, these screws ensure easy identification. The coarse thread (UNC) design offers robust grip strength, which is ideal for high-vibration applications, while the Zinc Yellow CR+3 finish provides superior corrosion resistance and an attractive look.

Enhanced Design Features:

• Increased Head Height: Slightly higher than standard hex screws per ASME B18.2.1, allowing better wrench engagement and reduced slippage.
• Radius Under Head: Reduces stress concentrations, minimizing the risk of fatigue-related failure.
• Smooth Washer-Bearing Surface: Provides uniform load distribution, preventing loosening under dynamic loads.

Key Mechanical Properties:

• Hardness: 38 to 42 HRC
• Surface Hardness: Maximum HR15N 81.5
• Tensile Strength: 180,000 PSI Minimum
• Yield Strength: 155,000 PSI Minimum
• Proof Load Strength: 145,000 PSI
• Elongation: 12% Minimum
• Reduction of Area: 35% Minimum
• Head Marking: Nine radial lines with "L9" for easy identification

Advanced Surface Finish:

• Zinc Yellow Plated: Meets ASTM F1941/F1941M Fe/Zn 5CN standards with a minimum thickness of 5 microns (0.0002").
• Yellow Trivalent (Cr+3) Coating: Provides excellent corrosion resistance, offering up to 96 hours of protection before red rust appears in salt spray testing.

Technical Specifications:

• Size: 5/8"-11 (Diameter: 0.625", Threads per Inch: 11)
• Length Options: Available in various lengths to fit your project needs (please select from options above)
• Material: High-Grade Alloy Steel (L9)
• Finish: Zinc Yellow CR+3 Plating for enhanced corrosion resistance
• Thread Type: Coarse Thread (UNC)
• Manufactured In: United States

Ideal Applications:

Our 5/8"-11 L9 Hex Head Cap Screws are designed for the toughest environments, including construction, heavy equipment, automotive, and industrial machinery. With their advanced strength and secure hold, they’re the perfect choice for assemblies exposed to high stress and vibration.

Full L9 Product Line

Order Yours Today!

Equip your projects with the strength and reliability of our 5/8"-11 L9 Hex Head Cap Screws. Order now to experience premium quality, fast shipping, and excellent customer service from Monster Bolts.