431 Hex flange bolts
ISO 4162ASTM A276 / ASTM A479
An integral flange spreads the bearing load of a 431 bolt. Hardenable stainless strength for loaded mechanical parts addresses the service exposure; plain or serrated seating determines contact with the supported surface.
- 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
Finished-Bolt 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
Integral flange
Use on mounting brackets and equipment covers to distribute head load over a wider seat and reduce loose parts during assembly. The flange needs a flat landing clear of nearby walls and radii.
Plain bearing face
Choose a plain underside for finished or coated seats where teeth would mark the surface. It also permits controlled sliding at the head-seat interface during tightening.
Flange vs loose washer
An integral flange speeds repeated assembly by keeping the bearing surface with the bolt. Retain a separate washer when the joint needs a replaceable wear face or a specifically hardened bearing layer.
- Head
- Hex drive · Integral flange
- Bearing face
- Plain or specified surface profile
- Length basis
- Under flange
- Threads
- Metric · UNC · UNF · UNJ
- Final condition
- Annealed · hardened and tempered
- Inspection
- Thread gauges · Head and shank dimensions
Manufacturing route
CNC machining suits samples and small lots. Cold heading or hot forging is selected for volume production according to alloy formability, head section and size.
Heat treatment & final condition
Hardening and tempering set the final hardness and toughness. Finish dimensions are checked after heat treatment.
Finished geometry
Head geometry, bearing face, shank and thread fit are checked after the final machining and thermal operations.
Where 431 fits — and what matters
Industrial Machinery & Automation
Machine frames and positioning fixtures431 hex flange bolts clamp machine frames and positioning fixtures through an integral flange that spreads head load over the mounting face. Alignment, operating cycles and replacement access define the working interface.
Automotive & EV Manufacturing Equipment
Assembly fixtures and test-rig frames431 hex flange bolts clamp assembly fixtures and test-rig frames through an integral flange that spreads head load over the mounting face. Repeated tooling changes require consistent seating and repeatable assembly dimensions.
Pumps, Valves & OEM
Actuator mounts and pump baseplates431 hex flange bolts clamp actuator mounts and pump baseplates through an integral flange that spreads head load over the mounting face. Repeated maintenance makes fit, engagement and access part of the component specification.
Same hex flange bolt. Different material priorities.
431 material data316L
Molybdenum-bearing stainless performance in wet equipment.
- Connection priority
- Clamp load spread over the integral flange
- 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 broad flange underside and its edge against the member in the exposure description.
17-4 PH
Aging-controlled strength and hardness.
- Connection priority
- Clamp load spread over the integral flange
- 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
- Clamp load spread over the integral flange
- 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 broad flange underside and its edge against the member 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
- Thread gauges · Head and shank dimensions
- Traceability
- EN 10204 3.1 material certificate · production lot · identified packing
Build your 431 hex flange bolt enquiry
Questions about 431 hex flange bolts
Can the flange replace a separate washer?
Only when its bearing footprint and the supported surface meet the assembly requirement. A serrated seat can damage a coating, while a thin or slotted member may need a different bearing arrangement.