Material specification page for all-metal hex flange lock nuts in A4 Stainless Steel. Covers the grade designation (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80), corrosion and magnetic behavior, comparable grades and their trade-offs, and the sizes available to GB/T 6187 / DIN 6927 / ASME B18.2.2.
Why Choose A4 Stainless Steel for All-Metal Hex Flange Lock Nuts
Specified for marine, coastal and chemical applications. For all-metal hex flange lock nuts, this matters when superior, including marine and chloride environments is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80 |
|---|---|
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C, subject to the property class and the joint |
| Corrosion characteristic | Superior, including marine and chloride environments |
Corrosion Behavior in Service
A4 (316) adds 2–3% molybdenum to the A2 (304) composition, which dramatically improves resistance to chloride-pitting corrosion. For All-Metal Hex Flange Lock Nuts in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Comparable Grades
For All-Metal Hex Flange Lock Nuts, the alternative stainless grade is A2 (304). A2 (304) covers general indoor and outdoor service. A4 (316) adds molybdenum, which is what buys the chloride resistance for marine and de-icing-salt exposure. Where strength matters more than corrosion, plated alloy steel in class 8.8 or 10.9 is the swap to make.
Using Stainless Fasteners in Aluminum
The galvanic couple here runs the wrong way: aluminum is the less noble metal, so it corrodes and the fastener does not. What governs the rate is the ratio of areas — a large anode and a small cathode is a tolerable combination, the reverse concentrates the attack into thin material around the hole. An isolating washer plus sealant breaks the circuit; where that is impractical, match the fastener to the substrate.
Sizes of All-Metal Hex Flange Lock Nuts Available in A4 Stainless Steel
| Strength class | Material | Locking method | Finish options | Service |
|---|---|---|---|---|
| 8 | carbon steel | deformed all-metal thread | black oxide or zinc | general vibration-exposed joints |
| 10 | carbon steel or alloy steel | deformed all-metal thread | black oxide or zinc | higher-preload vibration service |
| 12 | alloy steel | deformed all-metal thread | black oxide or zinc | high-temperature and high-preload service |
Dimensions are independent of the material: every size above is available in A4 Stainless Steel.
Custom manufacturing · Made to drawing
Need this nut in a grade that is not listed?
A4 Stainless Steel is one of the grades the catalog describes. Height and across-flats are the two most often changed — a thinner nut for clearance, a larger hex for a tool that is already on the line. Made by cold heading or tapping.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
