Nitronic 60 Flat Washers Specification

NITRONIC 60 Equivalent Designation
| UNS Designation | British STD | Werkstoff No. | European STD | Swedish STD | Japanese STD |
|---|---|---|---|---|---|
| S21800 | – | – | – | – | – |
Nitronic 60 Flat washers distribute clamp load over a wider bearing area, prevent surface damage, and accommodate bolt-hole oversize. TorqBolt manufactures Nitronic 60 Flat 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.
Nitronic 60 Flat 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.
Nitronic 60 Flat 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.
TorqBolt produces Nitronic 60 Flat 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.
Nitronic stainless steels are nitrogen-strengthened austenitic alloys that achieve high yield strength (1.5-2× conventional 304/316) without the heat-treatment required for precipitation-hardening grades. Nitrogen acts as a powerful interstitial solid-solution strengthener while remaining fully austenitic, retaining the corrosion resistance and toughness of standard austenitics.
Nitronic 50 (UNS S20910) is the dominant grade: 22Cr-13Ni-5Mn-2Mo-0.3N giving yield ~380 MPa in the annealed condition (vs ~205 MPa for 316L) and corrosion resistance better than 316L. The standard choice for high-strength corrosion-resistant fasteners in marine + chemical-process service. Nitronic 60 (S21800) trades some corrosion for outstanding galling and wear resistance — the workhorse for valve trim, threaded couplings, and wear-prone bolting where galling would destroy a 304/316 thread. Nitronic 32 / 33 / 40 are low-Ni variants for cost-sensitive applications.
Nitronic fasteners ship per ASTM A276 / A479 with EN 10204 3.1 / 3.2 certification covering nitrogen content (critical for property reproducibility), tensile, hardness, and stress-corrosion testing. NACE MR0175 sour-service is fully qualified in the annealed condition for both Nitronic 50 and 60.