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
Hiduron vs Toughmet 3
Hiduron 191 (UNS C72420) and Toughmet 3 (UNS C72900) are both high-strength copper-base alloys specified into subsea connectors and downhole hardware service, but they carry different strengthening mechanisms. Hiduron 191 is a Cu-Ni-Mn-Al alloy with gamma-prime Ni3Al precipitation hardening on the solution-anneal plus age cycle. Toughmet 3 is a Cu-Ni-Sn alloy with spinodal decomposition strengthening, where the tin addition drives a spinodal-modulated microstructure on the age cycle without forming a discrete precipitate phase. Both alloys carry seawater corrosion resistance, non-magnetic response and high-strength bolting envelopes; the two occupy adjacent positions on the subsea-connector materials selection table.
At a Glance: Hiduron 191 vs Toughmet 3
| Property | Hiduron 191 (C72420) | Toughmet 3 (C72900) |
|---|---|---|
| Family | Cu-Ni-Mn-Al precip-hardened | Cu-Ni-Sn spinodal-strengthened |
| Strengthening mechanism | Gamma-prime Ni3Al + Mn SS | Spinodal decomposition (Cu-Ni-Sn modulation) |
| Heat treatment | Solution anneal + age 475-525 C | Solution anneal + age 350-400 C |
| Tensile (Rm) | 820 to 1000 MPa | 900 to 1100 MPa |
| 0.2 percent proof | >=580 MPa | >=620 MPa |
| Hardness (HRC) | <=28 HRC for NACE | typically 22 to 30 HRC age-dependent |
| NACE MR0175 hardness ceiling | Qualified at 286 HBW (28 HRC) | Acceptance to heat lot; check ceiling |
| Magnetic permeability | <1.005 mu_r | <1.005 mu_r |
| Primary procurement | NES 835, DEF STAN 02-835, DOD-C-24676 | ASTM B505 (cast), proprietary mill spec |
| Primary use case | Naval bolting, splash zone, sour service | Subsea connector bodies, downhole hardware |
Chemistry Comparison
| Element | Hiduron 191 typical | Toughmet 3 typical |
|---|---|---|
| Cu | balance (~76 to 78) | balance (~77 to 79) |
| Ni | 14.0 to 15.5 | 14.5 to 15.5 |
| Sn | n/a | 7.5 to 8.5 |
| Al | 1.5 to 2.5 | n/a |
| Mn | 4.0 to 5.0 | up to 0.30 |
| Fe | 0.5 to 1.5 | up to 0.50 |
When to Specify Hiduron 191 vs Toughmet 3
- Specify Hiduron 191 when the application is Royal Navy or US Navy bolting and the procurement chain (NES 835, DEF STAN 02-835, DOD-C-24676) is binding. Toughmet 3 is not in scope of the naval procurement chain.
- Specify Hiduron 191 when the application carries a NACE MR0175 sour-service requirement at the 286 HBW (28 HRC) hardness ceiling. Hiduron 191 is qualified at the ceiling; Toughmet 3 acceptance is to heat lot and the hardness must be verified against the NACE limit.
- Specify Toughmet 3 when the application is a subsea connector body or downhole hardware component where the slightly higher strength envelope (Rp0.2 above 620 MPa) and the spinodal microstructure stability under load are the selection drivers, and the procurement chain is open to proprietary mill specifications.
- Cross-reference projects can specify either alloy on the materials selection table; the decision lands on the binding procurement chain and the NACE qualification path, not on the strength envelope alone.
Form Availability
Hiduron 191 is supplied in the bolting and machined-component form range (round bar, stud bolts, hex bolts, heavy hex bolts, anchor bolts, U-bolts, threaded rod, nuts, heavy hex nuts, washers, forgings, machined components) detailed in the shared Forms block below, with EN 10204 type 3.1 or 3.2 certification to NES 835, DEF STAN 02-835 or DOD-C-24676. Toughmet 3 is supplied in wrought rod and machined components from adjacent mill sources for subsea connector and downhole hardware applications.
Frequently Asked Questions
Q. What is the difference between Hiduron 191 and Toughmet 3?
Hiduron 191 is a Cu-Ni-Mn-Al alloy with gamma-prime Ni3Al precipitation hardening. Toughmet 3 (UNS C72900) is a Cu-Ni-Sn alloy with spinodal decomposition strengthening. Both are non-magnetic copper-base alloys with seawater corrosion resistance and high-strength bolting envelopes, but the strengthening mechanisms are different.
Q. Which has higher strength?
Toughmet 3 carries slightly higher tensile (900 to 1100 MPa vs 820 to 1000 MPa) and 0.2 percent proof (above 620 MPa vs above 580 MPa). The difference is small and within heat-to-heat variation; the selection decision typically lands on the procurement chain and the NACE qualification, not the strength envelope alone.
Q. Both NACE MR0175 qualified?
Hiduron 191 is qualified to NACE MR0175 at the 286 HBW (28 HRC) maximum hardness ceiling on the standard solution-anneal plus age cycle. Toughmet 3 NACE acceptance is verified to heat lot against the same hardness limit; the hardness should be verified on the mill test certificate before NACE-binding specification.
Q. Which carries the Royal Navy procurement chain?
Hiduron 191. The grade is the controlled alloy under NES 835, DEF STAN 02-835 (UK MoD) and DOD-C-24676 (US DoD). Toughmet 3 is supplied to proprietary mill specification and is not in scope of the formal naval procurement chain.
Q. Do you supply both?
TorqBolt supplies Hiduron 191 in the bolting and machined-component form range with EN 10204 type 3.1 or 3.2 certification to NES 835, DEF STAN 02-835 or DOD-C-24676. Toughmet 3 is sourced from adjacent mills for project supply when the cross-reference is required on the same purchase order.
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