Metric Zinc Plated Class 10.9 Steel Non-Serrated Flange Nuts
Class 10.9 Metric Non-Serrated Flange Nuts—also called smooth flange nuts, plain flange nuts, washer face nuts, or free-spinning flange nuts—combine a standard hex nut with an integrated flat washer flange at the base, manufactured from high-strength Class 10.9 alloy steel. Unlike serrated flange nuts that grip and dig into surfaces, non-serrated flange nuts feature a smooth bearing surface that allows the nut to rotate freely during tightening without scratching, marring, or damaging the material underneath. This makes them the preferred choice for high-strength applications involving painted, powder-coated, anodized, or polished surfaces where both surface protection and superior clamping force are critical.
Why Choose Class 10.9 Non-Serrated Flange Nuts?
Class 10.9 steel delivers significantly higher strength than standard Class 8.8 fasteners, with a minimum tensile strength of 1,040 MPa (150,000 PSI) and yield strength of 940 MPa. This makes Class 10.9 non-serrated flange nuts ideal for heavy-duty assemblies, high-torque applications, and critical joints where fastener failure is not an option. The smooth flange design distributes clamping force across a larger area, reducing stress concentration and preventing pull-through on softer materials like aluminum, plastic, fiberglass, and thin sheet metal. Because the flange acts as a built-in washer, these nuts eliminate the need for a separate flat washer—saving assembly time, reducing part count, and lowering overall fastener costs without sacrificing strength.
Material & Specifications
Our Class 10.9 metric non-serrated hex flange nuts are manufactured from quenched and tempered alloy steel, heat-treated to achieve the mechanical properties required for high-stress fastening applications. Class 10.9 is the metric equivalent of SAE Grade 8, the highest strength grade commonly available for commercial fasteners. The zinc plated finish provides corrosion resistance for indoor use and moderate outdoor exposure while facilitating smoother installation and visual inspection of installed hardware. Zinc plating meets RoHS compliance standards for environmentally responsible manufacturing.
Class 8.8 vs. Class 10.9: Which Strength Grade Do You Need?
Selecting the correct strength grade ensures safe, reliable performance in your application. Class 8.8 fasteners are suitable for most general-purpose and medium-duty applications, offering a tensile strength of approximately 800 MPa. Class 10.9 fasteners provide roughly 25-30% greater tensile and yield strength, making them necessary for heavy-duty, high-vibration, or safety-critical assemblies. When in doubt, consult engineering specifications or upgrade to Class 10.9 for added safety margin in demanding applications.
Common Applications
Class 10.9 metric smooth flange nuts are specified across industries where high-strength fastening and surface protection are both required:
- Automotive & Motorsports: Suspension components, drivetrain assemblies, engine mounts, roll cages, chassis reinforcement
- Heavy Equipment & Machinery: Structural frames, hydraulic systems, high-load brackets, industrial presses
- Agricultural & Construction Equipment: Implements, loader arms, attachment points, cab assemblies
- Aerospace & Defense: Non-flight-critical assemblies, ground support equipment, vehicle armor mounting
- Structural & Steel Fabrication: Bolted connections, equipment anchoring, safety-critical joints
Serrated vs. Non-Serrated Flange Nuts: Which Do You Need?
Choosing between serrated and non-serrated flange nuts depends on your application requirements. Serrated flange nuts feature teeth on the flange that bite into the mating surface, providing vibration resistance and locking action—but they will permanently mark the surface. Non-serrated (smooth) flange nuts allow free rotation and protect surface finishes but do not provide inherent locking capability. For high-strength applications requiring vibration resistance with a smooth flange nut, consider using a thread locker compound or pairing with a separate lock washer.
Available Sizes
We stock Class 10.9 metric non-serrated flange nuts in a range of popular sizes to cover most heavy-duty applications. Whether you need smaller diameter nuts for equipment assemblies or larger sizes for structural connections, Albany County Fasteners has you covered with competitive bulk pricing and same-day shipping on in-stock items.
Can't find the size or grade you need? Contact our team—with over 18 million fasteners in stock, we can help you source the right metric flange nut for your project.