431 Slotted & castle nuts
DIN 935-1ASTM A276 / ASTM A479
431 castle and slotted nuts combine hardenable stainless strength for loaded mechanical parts with visible pin retention. The cross-hole, pin and nut slots complete the system; the nut’s material condition governs its loaded thread.
- 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
Slotted nut
Use on drilled shafts and pins where a cotter pin retains the nut after adjustment. Slots in the hex body provide a lower axial envelope when the installation has limited clearance.
Castle nut
Use the raised slotted crown to position the cotter-pin path above the wrenching body. The crown needs clearance beyond the bearing assembly or linkage end.
Pin alignment
For wheel, pivot and linkage assemblies, align the slots with the cross-hole using the assembly’s preload or end-play procedure. The pin retains the nut; it does not set the bearing adjustment.
- Retention
- Slots · Split pin
- Mating part
- Cross-drilled bolt or shaft
- Patterns
- Slotted · Castellated
- Threads
- Metric · Inch
- Final condition
- Annealed · hardened and tempered
- Inspection
- Slot width · Crown height · Pin clearance · 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
Drive shafts, collars and guide pins431 slotted & castle nuts retain drive shafts, collars and guide pins with a split pin through the nut slots and a cross-drilled shaft. Slot alignment establishes the final positive-retention position. Alignment, operating cycles and replacement access define the working interface.
Automotive & EV Manufacturing Equipment
Fixture pins and positioning shafts431 slotted & castle nuts retain fixture pins and positioning shafts with a split pin through the nut slots and a cross-drilled shaft. Slot alignment establishes the final positive-retention position. Repeated tooling changes require consistent seating and repeatable assembly dimensions.
Pumps, Valves & OEM
Valve stems and pump-drive collars431 slotted & castle nuts retain valve stems and pump-drive collars with a split pin through the nut slots and a cross-drilled shaft. Slot alignment establishes the final positive-retention position. Repeated maintenance makes fit, engagement and access part of the component specification.
Same slotted & castle nut. Different material priorities.
431 material data316L
Molybdenum-bearing stainless performance in wet equipment.
- Connection priority
- Nut preload with separate positive pin retention
- 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 pin slots, cross-drilled shaft and bearing face in the exposure description.
17-4 PH
Aging-controlled strength and hardness.
- Connection priority
- Nut preload with separate positive pin retention
- 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
- Nut preload with separate positive pin retention
- 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 pin slots, cross-drilled shaft and bearing face 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
- Slot width · Crown height · Pin clearance · Threads
- Traceability
- EN 10204 3.1 material certificate · production lot · identified packing
Build your 431 slotted & castle nut enquiry
Questions about 431 slotted & castle nuts
What must be specified with a castle nut?
The cross-drilled shaft, retaining pin material and slot geometry complete the retention system. Slot alignment follows the assembly tightening procedure; the pin does not generate the joint’s clamp load.