5/16"-18 L9 Hex Head Cap Screw – Coarse Thread Alloy Steel Zinc Yellow CR+3 (Made in U.S.A.)

5/16"-18 L9 Hex Head Cap Screw – Coarse Thread Alloy Steel Zinc Yellow CR+3 (Made in U.S.A.)

Part Numbers: 440086, 440090 ,440094, 440096, 440098, 440100, 440102 ,440104, 440106, 440110, 440114, 440118

Introducing our premium 5/16"-18 L9 Hex Head Cap Screws, designed to provide exceptional performance in high-stress environments. Manufactured in the USA, these bolts are made from high-grade alloy steel, ensuring peak strength and reliability. With a tensile strength of 180,000 PSI, these screws are ideal for critical applications that demand the utmost durability and resistance to loosening.

Why Choose L9 Hex Head Cap Screws?

L9 fasteners represent the highest SAE grading for hex cap screws, specifically crafted for industries where strength and longevity are essential. Identified by the "L9" marking and nine radial lines on the head, these screws are easy to recognize and trusted for their superior quality. The coarse thread (UNC) design offers robust grip strength, optimal for securing in high-vibration environments. Zinc Yellow CR+3 plating provides excellent corrosion resistance and a professional finish.

Enhanced Design Features:

• Increased Head Height: Slightly higher than standard hex screws per ASME B18.2.1, allowing for better wrench contact and reduced slippage.
• Radius Under Head: Reduces stress concentrations, adding strength against fatigue failure.
• Smooth Washer-Bearing Surface: Ensures even load distribution to prevent 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 96 hours of red rust protection in salt spray testing, enhancing durability.

Technical Specifications:

• Size: 5/16"-18 (Diameter: 0.3125", Threads per Inch: 18)
• Length Options: Available in various lengths (select above)
• Material: High-Grade Alloy Steel (L9)
• Finish: Zinc Yellow CR+3 Plating
• Thread Type: Coarse Thread (UNC)
• Manufactured In: United States

Ideal Applications:

Our 5/16"-18 L9 Hex Head Cap Screws are perfect for use in industries where maximum strength and quick assembly are key, including construction, heavy equipment, automotive, and aerospace. Built for performance, they offer enhanced reliability even in the toughest conditions.

Full L9 Product Line

Order Yours Today!

Secure your assemblies with the unmatched strength of our 5/16"-18 L9 Hex Head Cap Screws. Order now to ensure top-quality fasteners for your demanding projects and benefit from fast shipping and customer support from Monster Bolts.