431 Serrated flange nuts
ISO 4161ASTM A276 / ASTM A479
431 serrated flange nuts engage the member directly through their toothed seat. Hardenable stainless strength for loaded mechanical parts concerns the nut body; the substrate exposed by the serrations remains part of the same connection.
- MOQ
- 100PCS
- Samples · typical
- ~20 days
- Production · typical
- 25–35 days
- Heat treatment
- Annealed / hardened and tempered
EN 10204 3.1 MTC + heat-number traceability
Which standard is on your order?
Raw Material Specifications
Threads · Metric
Threads · Inch
Dimension Reference
Heat Treatment
Hardened and temperedHardening forms the load-bearing martensitic structure, then tempering adjusts hardness and toughness to the specified final condition.
What we can make in 431
Body height: regular / tall
- Regular height
- Fits compact equipment covers and mounting brackets where clearance above the nut is limited.
- Tall body
- Provides longer thread engagement on clamping studs in jigs, fixtures and machine-tool setups that are tightened and released repeatedly.
Bearing face: plain / serrated
- Plain face
- For painted covers and finished equipment faces where serration marks are unwanted.
- Serrated face
- For metal mounting brackets where teeth can bite directly into the seat to resist rotation.
All configurations shown are available on request.
- Bearing face
- Serrated flange
- Drive
- External hex
- Threads
- Metric · Inch
- Key dimensions
- Flange diameter · Nut height
- Final condition
- Annealed · hardened and tempered
- Inspection
- Flange diameter · Serrations · Nut height · Threads
Manufacturing route
Small lots use machined blanks. Volume nut blanks use a forming route compatible with the alloy before machining the bore and tapping.
Heat treatment & final condition
Hardening and tempering set the final hardness and toughness. Finish dimensions are checked after heat treatment.
Finished geometry
Internal thread gauging, usable engagement and bearing-face alignment are checked after final processing.
Where 431 fits — and what matters
Industrial Machinery & Automation
Machine frames and positioning fixtures431 serrated flange nuts clamp machine frames and positioning fixtures through a serrated flange that engages the mounting face. The mating surface must accept the serration contact. Alignment, operating cycles and replacement access define the working interface.
Automotive & EV Manufacturing Equipment
Assembly fixtures and test-rig frames431 serrated flange nuts clamp assembly fixtures and test-rig frames through a serrated flange that engages the mounting face. The mating surface must accept the serration contact. Repeated tooling changes require consistent seating and repeatable assembly dimensions.
Pumps, Valves & OEM
Actuator mounts and pump baseplates431 serrated flange nuts clamp actuator mounts and pump baseplates through a serrated flange that engages the mounting face. The mating surface must accept the serration contact. Repeated maintenance makes fit, engagement and access part of the component specification.
Same serrated flange nut. Different material priorities.
431 material data316L
Molybdenum-bearing stainless performance in wet equipment.
- Connection priority
- Bearing and tooth engagement against the member
- Washdown and retained cleaner
- Cleaner concentration, rinse quality and deposits determine the exposure in covered joints. The low-carbon designation does not independently establish a fastener strength class. Include liquid retained at the serration tips and the covered flange seat in the exposure description.
17-4 PH
Aging-controlled strength and hardness.
- Connection priority
- Bearing and tooth engagement against the member
- H900 versus H1150
- The aging condition changes the balance of strength, hardness and toughness. A replacement part needs the specified H condition, especially where contact wear and shock load occur together.
Inconel 625
Solid-solution strength and resistance to aggressive process liquids.
- Connection priority
- Bearing and tooth engagement against the member
- Annealed or solution-annealed 625
- The delivery condition affects strength and high-temperature response. Keep the specified condition with the component’s mechanical acceptance; 718-style aging is not the strengthening route for 625. Include liquid retained at the serration tips and the covered flange seat in the exposure description.
From drawing to documented delivery
- 01Drawing & BOMForm, dimensions and quantity
- 02Material & formingGrade, heat and manufacturing route
- 03Final inspectionGeometry, threads and ordered tests
- 04Documents & dispatchLot records and identified packing
Order documents
- Material identity
- UNS S43100 · heat number · ordered condition
- Final-part acceptance
- Hardness and mechanical acceptance after hardening and tempering.
- Dimensional record
- Flange diameter · Serrations · Nut height · Threads
- Traceability
- EN 10204 3.1 material certificate · production lot · identified packing
Build your 431 serrated flange nut enquiry
Questions about 431 serrated flange nuts
Will serrations preserve a coated bearing surface?
Serrations work by engaging the surface and can break its coating. Include the exposed substrate in the corrosion assessment; the nut’s own alloy cannot protect coating damage underneath it.