| UNS Designation | British STD | Werkstoff No. | European STD | Swedish STD | Japanese STD |
|---|---|---|---|---|---|
| – | – | – | – | – | – |
Mp 35n Square nuts are internally threaded fasteners that mate with bolts and studs to form clamped joints. TorqBolt manufactures Mp 35n Square nuts per ASME B18.2.2, ISO 4032/4033/4034, DIN 934/EN 24032, and DIN 6915 (heavy hex), in sizes M6–M100 and 1/4"–4".
For vibration-loaded joints, Mp 35n Square nuts are available as nyloc (polymer insert), all-metal prevailing-torque (DIN 980, distorted-thread style), flange-serrated (DIN 6923, integral washer face with anti-back-off teeth), and castle / slotted (DIN 935, cotter-pin retention). Each locking style trades reusability against prevailing-torque retention.
Mp 35n Square nut threads are gauged per ASME B1.1 / ISO 965 to Class 2B / 6H by default; high-strength variants use 3B / 4H6H. Proof-load testing per ASTM F606 verifies the nut can develop the bolt's full strength without thread strip; hardness range is controlled to prevent stress-corrosion susceptibility (HV 250–353 typical for high-grade nuts). Each lot is EN 10204 3.1 / 3.2 certified.
TorqBolt also produces Mp 35n Square nuts in weld-nut, T-nut, square-nut, knurled thumb-nut, and rivet-nut patterns. NACE MR0175 / ISO 15156 sour-service certification available; NORSOK M-650 qualified mills supplying high-temperature service grades.
MP35N (UNS R30035) is a multiphase nickel-cobalt-chromium-molybdenum alloy combining ultra-high tensile strength with outstanding corrosion resistance — positioned where Inconel 718 lacks sufficient corrosion resistance and Hastelloy C-276 lacks sufficient strength. The cold-work + age-hardening response yields tensile strength >2000 MPa with excellent fatigue and stress-corrosion performance.
The MP35N microstructure is a two-phase mix of fcc + hcp regions; specific cold-work reduction (40-50%) followed by ageing at 540-650°C transforms the matrix to deliver the alloy's signature combination of strength + corrosion resistance. Composition centers on ~35% Ni, 35% Co, 20% Cr, 10% Mo.
MP35N is the dominant material for sour-well wireline + casing bolting, downhole completion equipment, surgical implants requiring biocompatibility + fatigue strength, and high-pressure aerospace fasteners. The alloy is fully qualified to NACE MR0175 / ISO 15156 across the standard hardness range (up to ~52 HRC), making it one of the few materials capable of meeting both extreme-strength and sour-service criteria simultaneously.
MP35N fasteners are supplied per ASTM F562 / AMS 5844 / 5845 with EN 10204 3.2 third-party-witnessed certification including chemistry, mechanicals, hardness, fatigue, and stress-corrosion testing. Welding is generally avoided; mechanical joints with matching MP35N hardware are preferred.