904L Socket head cap screws
ISO 4762ASTM A276
Where tool access is axial, 904L socket head cap screws bring molybdenum- and copper-bearing resistance to selected acids into a compact head envelope. Counterbore seating and housing-thread engagement determine how the available strength is used.
- MOQ
- 100PCS
- Samples · typical
- ~20 days
- Production · typical
- 25–35 days
- Heat treatment
- Solution annealed
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
Solution annealedSolution annealing and rapid cooling retain alloying elements in solution and restore the specified corrosion-resistant condition.
What we can make in 904L
Partial thread
Use where a plain grip must span the clamped components. Match the under-head length and thread length so the screw tightens the stack before its thread runout reaches the tapped hole.
Full thread
Use for shorter component stacks and varied tapped-hole depths. The longer usable thread offers adjustment, while the screw end must clear the bottom of a blind hole.
- Drive
- Internal hex socket
- Length basis
- Under head
- Thread systems
- Metric · UNC · UNF · UNJ
- Assembly
- Tapped holes · Nuts
- Final condition
- Solution annealed
- 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
The final annealed or specified strengthened condition is linked to the lot; an aging treatment is not assumed for a solid-solution alloy.
Finished geometry
Head geometry, bearing face, shank and thread fit are checked after the final machining and thermal operations.
Where 904L fits — and what matters
Chemical Processing
Chemical pump covers and reactor connections904L socket head cap screws fasten chemical pump covers and reactor connections with axial tool access inside a head counterbore. The socket and under-head seat remain accessible for service removal. Process liquid can remain at the contact after the exposed surface drains.
Pumps, Valves & OEM
Pump casings and valve bonnets904L socket head cap screws fasten pump casings and valve bonnets with axial tool access inside a head counterbore. The socket and under-head seat remain accessible for service removal. Repeated maintenance makes fit, engagement and access part of the component specification.
Mining & Mineral Processing
Chemical-recovery pump and vessel covers904L socket head cap screws fasten chemical-recovery pump and vessel covers with axial tool access inside a head counterbore. The socket and under-head seat remain accessible for service removal. Leach solution and deposits act on the installed part; corrosion duty is separate from abrasive wear.
Same socket head cap screw. Different material priorities.
904L material dataHastelloy C-276
Resistance to chemically aggressive, mixed process streams.
- Connection priority
- Clamp load through the cylindrical head and engaged housing thread
- Process liquid and shutdown chemistry
- C-276 is selected for its nickel–chromium–molybdenum–tungsten chemistry. Residual product, cleaning liquid and oxidising contamination can expose a sheltered connection differently from the main flow. Include liquid retained at the socket recess and the under-head seating pocket in the exposure description.
Inconel 625
Solid-solution strength and resistance to aggressive process liquids.
- Connection priority
- Clamp load through the cylindrical head and engaged housing thread
- 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 socket recess and the under-head seating pocket in the exposure description.
Hastelloy C-22
Corrosion resistance across oxidising and reducing process exposures.
- Connection priority
- Clamp load through the cylindrical head and engaged housing thread
- Production and cleaning cycles
- C-22’s chromium-bearing chemistry is relevant when chemical exposure changes between operating and cleaning cycles. Include both liquids when comparing it with C-276 or a B-type nickel alloy. Include liquid retained at the socket recess and the under-head seating pocket 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 N08904 · heat number · ordered condition
- Final-part acceptance
- Grade chemistry, supplied condition and ordered mechanical requirements.
- Dimensional record
- Thread gauges · Head and shank dimensions
- Traceability
- EN 10204 3.1 material certificate · production lot · identified packing
Build your 904L socket head cap screw enquiry
Questions about 904L socket head cap screws
What changes when the screw is stronger than the housing?
The housing thread can strip before the screw reaches its tensile capacity. The engagement depth and housing material therefore belong in the joint assessment alongside the screw’s final strength condition.