Cupronickel 70-30 Lock washers manufactured at TorqBolt are seawater resistant,crevice resistant,stress corrosion crack resistant & hydrogen embrittlement resistant.
Dimensional standards as per DIN 6797,DIN 6827 are provided.
The raw material of these fasteners is classified as copper based nickels. Being a PED certified Fasteners Manufacturer by TUV Rheinland,our fasteners are accompanied with EN 10204 3.1/3.2 certification. Cupronickel 70-30 Lock washers are available in hot forged,cold forged and bar stock machined conditions depending upon the order quantity.
Cupronickel 70 30 Lock washers distribute clamp load over a wider bearing area, prevent surface damage, and accommodate bolt-hole oversize. TorqBolt manufactures Cupronickel 70 30 Lock washers per ASME B18.21.1 / B18.22.1, DIN 125 / 126 / 127 / 9021, and ISO 7089 / 7090 / 7093 / 7094, in metric (M3–M100) and imperial (#4–4") sizes.
Plain Washer Dimensions
Cupronickel 70 30 Lock plain washers are characterized by three critical dimensions: ID (clearance over bolt diameter), OD (load distribution area), and thickness (compressive stiffness). Standard tolerances are h13 on OD and H13 on ID per ISO 286-2; flatness 0.05 mm/100 mm and parallelism 0.05 mm/100 mm verified per lot. Edge break / chamfer per drawing.
Form Variants
Form A (regular) — DIN 125-A / ISO 7089, the default plain washer
Form B (large OD) — DIN 9021 / ISO 7093, for soft mating surfaces
Form C (heavy) — DIN 7349 / ISO 7094, for slotted holes / structural use
Spring (split) — DIN 127 / ASME B18.21.1, helical anti-vibration
Conical / Belleville (DIN 6796 / 2093) — preload maintenance
Hardness & Surface
Cupronickel 70 30 Lock washers are hardness-controlled to balance load-distribution stiffness against surface damage to mating parts. Typical Vickers HV ranges: plain 140–180 HV; spring 380–440 HV; Belleville 460–540 HV. Surface finish Ra 1.6 µm or better; on critical sealing applications, Ra 0.8 µm available.
Special Patterns
TorqBolt produces Cupronickel 70 30 Lock washers in square (DIN 436), fender (oversized OD), tab / lock-tang (DIN 462 / 463), and spherical seat washer + cup combinations. EN 10204 3.1 / 3.2 material certificates standard; NACE MR0175 / ISO 15156 on request.
Copper-Nickel & Cupronickel Alloys
Copper-nickel (cupronickel) alloys combine copper's bio-fouling resistance with nickel's strength and corrosion enhancement. The two production grades dominate marine + desalination service where titanium is too costly: 90/10 Cu-Ni (~90% Cu, 10% Ni) and 70/30 Cu-Ni. Cu-Ni alloys are the only commercial materials inherently resistant to marine bio-fouling, eliminating the need for antifouling coatings on heat-exchanger tubes and ship hulls.
C70600 (90/10 Cu-Ni) is the high-volume marine alloy: yield ~105 MPa, used for desalination tubing, condenser tubes, hull cladding, and offshore piping fasteners. C71500 (70/30 Cu-Ni) increases nickel for higher strength (~160 MPa yield) and better seawater erosion-corrosion at higher flow velocities — the choice for naval condensers and high-pressure desalination. C71640 (70/30 + Fe + Mn) extends service to even higher flow rates.
Cu-Ni fasteners ship per ASTM B151 (rod/bar) and B171 (plate/forging) with EN 10204 3.1 / 3.2 certificates. Welding uses ERCuNi or ENiCu-7 filler with low-heat-input technique to avoid hot cracking. NACE MR0175 sour-service application is limited; ammoniacal stress-corrosion can occur if exposed to NH₃ in service.
