Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Monel 400 Screws - Machine, Cap, Pan & Flat Head, UNS N04400
Monel® 400 screws cover the full small-fastener family: Monel 400 machine screws, cap screws, self-tapping screws, plus sheet-metal variants on indent. UNS N04400 screws are dimensionally controlled by two standards. ASTM F468 governs thread diameters 1/4 in and larger (the Monel 400 cap-screw envelope). Machine screws below 1/4 in (No. 0000 through 1/4 in) sit under ASME B18.6.3 for slotted and recessed head dimensional control, with chemistry referenced to ASTM B164 rod bar. Monel is a registered trademark of Special Metals Corporation; TorqBolt is not authorized by, affiliated with or endorsed by Special Metals.
Screw vs Bolt: Where the Boundary Sits
A screw drives into a tapped hole (or forms its own thread in soft host material) with the head bearing into the joint. A bolt mates with a separate nut and clamps under an external wrench. For Monel 400 procurement three practical buckets cover 95 percent of small-fastener demand: machine screws (No. 0000 to 1/4 in, ASME B18.6.3), cap screws (1/4 in to 1 in into a tapped hole, dimensional control per ASTM F468 or ASME B18.3 for socket cap screws), and self-tapping screws (Type A, AB, B, BP under ASME B18.6.3 Section 4).
Machine Screw Head Styles (ASME B18.6.3)
ASME B18.6.3 recognises ten head families. The five highest-velocity styles for Monel 400 are pan, flat countersunk (82 deg), oval countersunk, fillister and round. Pan supersedes round in modern designs (ASME B18.6.3 paragraph 2.2.7 recommends substitution wherever possible). Flat countersunk requires a chamfered hole and finishes flush. Fillister is the long-cylindrical option for counterbored holes where head-side clearance is tight. Truss (low rounded, wide bearing) is specified where the screw bears on thin sheet without an external washer.
| Head style | Top surface | Bearing | Typical use |
|---|---|---|---|
| Pan | Rounded, blends to cylindrical sides | Flat, perpendicular | Default cross-recessed driver, panel mount |
| Flat countersunk (82 deg) | Conical, 82 deg included angle | Conical (flush) | Flush-mount in chamfered hole |
| Oval countersunk (82 deg) | Domed top, conical underside | Conical (flush) | Decorative flush mount, naval cabinetry |
| Fillister | Rounded top, long cylindrical sides | Flat | Counterbored hole, head-side clearance tight |
| Round | Semi-elliptical (legacy) | Flat | Legacy assemblies; substitute pan in new designs |
| Truss | Low rounded, larger diameter than pan | Flat, wide | Thin sheet, no washer required |
| Hex / hex washer | Six flat sides, flat or indented top | Flat (plain) or flat with integral washer | Driver-accessible heads, sheet-metal lay-up |
Self-Tapping Screws (Limited Availability in Monel 400)
Self-tapping screws in Monel 400 are available on indent rather than ex-stock. The dominant production stream for self-tapping is low-carbon steel (ASME B18.6.3 paragraph 4.7.1 references 1006 through 1022 with Rockwell B69 to 100 baseline), and nickel-copper work-hardens during the forming step in a way that requires tighter tool maintenance. Where seawater, hydrofluoric acid vapour or sour gas wet the screw, the buyer pays the indent premium. Five thread-forming types are catalogued (A, AB, B, BP, U for metallic drive; with thread-cutting variants BF, BT, D, F, G, T and thread-rolling for chip-free installation in untapped holes). The most ordered Monel 400 variants are Type AB (gimlet point, thin metal and resin-impregnated plywood) and Type B (blunt point, non-ferrous castings and plastics).
Drive Types and Recess Geometry
Drive selection is independent of head style. Slot and Phillips Type I cross recess dominate stocked Monel 400 machine screws; Type IA (Pozidrive) penetration gaging follows ASME B18.6.3 Mandatory Appendix III. Six-lobe (Torx) drive is specified where cam-out must be eliminated under high torque. Hex socket (per ASTM F912 / ISO 4762 envelope) is the default for socket cap screws and the highest-torque option on small diameters because it transfers load through six flank surfaces.
| Drive | Standard | Cam-out | Typical use |
|---|---|---|---|
| Slot | ASME B18.6.3 para 2.1.4 | High | Stocked machine screws, hand assembly |
| Phillips Type I | ASME B18.6.3 Appendix III | Moderate (by design) | Default cross recess on stocked screws |
| Type IA / Pozidrive | ASME B18.6.3 Appendix III | Low | Powered driver, no cam-out |
| Square (Robertson) | ASME B18.6.3 Appendix VII | Very low | Cabinet, wood-host applications |
| Hex socket | ASTM F912 / ISO 4762 | None | Socket cap screw, high-torque clamp |
| Torx (six-lobe) | ISO 10664 | None | High torque, security variants on request |
Size Range Stocked
The Monel 400 screw envelope runs #2 (0.086 in basic) to 5/8 in for cap screws, M2 to M16 for metric. The transition between ASME B18.6.3 (below 1/4 in) and ASTM F468 (1/4 in and above) sits at the 1/4 in line in Imperial and approximately M6 in metric. Sizes No. 0000, No. 000 and No. 00 ship on indent for instrumentation and electronics housings (ASME B18.6.3 Mandatory Appendix V).
| Imperial size | Basic dia (in) | UNC tpi | UNF tpi | Governing standard |
|---|---|---|---|---|
| #2 | 0.086 | 56 | 64 | ASME B18.6.3 |
| #4 | 0.112 | 40 | 48 | ASME B18.6.3 |
| #6 | 0.138 | 32 | 40 | ASME B18.6.3 |
| #8 | 0.164 | 32 | 36 | ASME B18.6.3 |
| #10 | 0.190 | 24 | 32 | ASME B18.6.3 |
| #12 | 0.216 | 24 | 28 | ASME B18.6.3 |
| 1/4 | 0.250 | 20 | 28 | ASTM F468 / ASME B18.6.3 boundary |
| 5/16 | 0.3125 | 18 | 24 | ASTM F468 |
| 3/8 | 0.375 | 16 | 24 | ASTM F468 |
| 1/2 | 0.500 | 13 | 20 | ASTM F468 |
| 5/8 | 0.625 | 11 | 18 | ASTM F468 |
Metric stocked: M2, M2.5, M3, M4, M5, M6, M8, M10, M12, M16. M3 and M4 dominate instrumentation; M5 and M6 dominate cabinetry and panel mount.
Mechanical Properties (F468 above 1/4 in, B18.6.3 below)
Above the 1/4 in boundary the F468 tensile and yield minima apply: the Monel 400 cap screw at 0.250 to 0.750 in carries 80 to 130 ksi tensile (552 to 896 MPa) and 40 ksi yield (276 MPa minimum), with a 25 HRC hardness ceiling. Detail on the F468 marking system and class breakdown is on the ASTM F468 page and the bolts page. Below the 1/4 in line, ASME B18.6.3 does not impose mechanical minima on the screw itself; the screw inherits the parent-bar property envelope from ASTM B164 (annealed: 70 ksi tensile, 25 ksi yield, 35 percent elongation as the base condition for sizes through 2 in). Cold-drawn bar shifts the tensile higher (90 to 110 ksi) with elongation around 25 percent. For the full alloy property envelope see mechanical properties.
Applications
Three application clusters absorb the Monel 400 screw output. (1) Instrumentation: pressure transmitter housings on offshore platforms, gauge mounting brackets in HF alkylation units, valve actuator covers in seawater service. Size envelope M3 to M6 (or #4 through #12). (2) Naval and marine: bulkhead cabinetry, switchboard panel screws, non-magnetic instrument mount, deck hardware. Magnetic permeability of Monel 400 sits below 1.005, which is the reason the naval bulkhead spec routes to nickel-copper rather than 304 or 316 stainless. (3) Marine cabinetry and joinery: cabin door hinges, locker stays, drawer slides. Detail on the corrosion envelope is on corrosion resistance and the marine application breakdown on marine applications; magnetic permeability data on magnetic permeability.
Frequently Asked Questions
Are Monel 400 screws covered by ASTM F468? Yes, for nominal diameters 1/4 in and larger. Machine screws below 1/4 in are dimensionally controlled by ASME B18.6.3 with the chemistry sourced from ASTM B164 bar.
What head styles are available? Pan, flat countersunk (82 deg), oval countersunk, fillister, round, truss, binding, hex and hex washer. Pan is the modern default for cross-recessed drives.
What drive types? Slot, Phillips Type I, Type IA, square Robertson, hex socket and Torx. Phillips and slot dominate stock; hex socket is the cap-screw default.
Is self-tapping Monel 400 available? Yes, on indent. Type AB and Type B per ASME B18.6.3 Section 4 are the most ordered variants in UNS N04400.
How is the certificate issued? EN 10204 type 3.1 standard; type 3.2 with third-party witness on request. Heat number traceable to ASTM B164 parent bar.
Related Pages
For larger thread diameters see Monel 400 bolts, the hex cap screw envelope at cap screws, the internal-hex variant at socket cap screws, and the governing spec at ASTM F468. Companion nuts at hex nuts (ASTM F467), washers and threaded rod. Alloy reference: UNS N04400, nickel-copper alloy background, chemical composition.
Request a Quote
Send size, head style, drive, length, finish and quantity to info@torqbolt.com or WhatsApp +91-22-66157017. Ex-Mumbai price and lead time returned within one working day. Domestic India 3 to 7 working days; export through JNPT. Pricing page for budgetary indication.
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