A4 Stainless Steel (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80) is specified for marine, coastal and chemical applications. When low and high cap (acorn) nuts, inch are specified in this grade, the dimensions remain per SAE J483; the material determines corrosion behavior (superior, including marine and chloride environments) and the service temperature range (approx. -200 °C to +400 °C, subject to the property class and the joint). Both are covered below with the size table.
Why Choose A4 Stainless Steel for Low and High Cap (Acorn) Nuts, Inch
Specified for marine, coastal and chemical applications. For low and high cap (acorn) nuts, inch, 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 |
Galvanic & Galling Considerations
Two important notes for stainless low and high cap (acorn) nuts, inch: (1) stainless can gall on stainless threads under load — use a thread lubricant or anti-galling compound, especially for M6 and below; (2) when joined to aluminum or galvanized steel, stainless can drive galvanic corrosion of the less-noble metal in wet service — isolate with a coating or sleeve where appropriate.
Comparable Grades
For Low and High Cap (Acorn) Nuts, Inch, the alternative stainless grade is A2 (304). The practical dividing line is chlorides: A2 (304) is fine until salt is involved, and A4 (316) exists for the cases where it is — coastal, marine and road-salt service. Neither reaches the strength of a plated class 8.8 or 10.9 fastener.
Using Stainless Fasteners in Aluminum
Stainless steel is more noble than aluminum, so with an electrolyte present — rain, condensation, salt spray — the aluminum becomes the anode and corrodes at the joint. Area ratio decides how bad it gets: a small stainless fastener in a large aluminum section is normally acceptable, a large stainless fastener in thin aluminum is not. Where the joint gets wet, isolate the metals with a coated or nylon washer and a sealant, or specify an aluminum or coated fastener instead.
Sizes of Low and High Cap (Acorn) Nuts, Inch Available in A4 Stainless Steel
| Size | Type | Threads per inch | Width across flats s (in) | A (in) | Nut height m (in) | Q (in) | U (in) | Reference standard |
|---|---|---|---|---|---|---|---|---|
| #6 | Low cap nuts | 32 | 0.312 | 0.3 | 0.34 | 0.16 | 0.16 | SAE J483 |
| #8 | Low cap nuts | 32 | 0.312 | 0.3 | 0.34 | 0.16 | 0.16 | SAE J483 |
| #10 | Low cap nuts | 24 | 0.375 | 0.36 | 0.41 | 0.19 | 0.19 | SAE J483 |
| #12 | Low cap nuts | 24 | 0.375 | 0.36 | 0.41 | 0.19 | 0.22 | SAE J483 |
| 1/4" | Low cap nuts | 20 | 0.438 | 0.41 | 0.47 | 0.22 | 0.25 | SAE J483 |
| 5/16" | Low cap nuts | 18 | 0.5 | 0.47 | 0.53 | 0.25 | 0.31 | SAE J483 |
| 3/8" | Low cap nuts | 16 | 0.562 | 0.53 | 0.62 | 0.28 | 0.38 | SAE J483 |
| 7/16" | Low cap nuts | 14 | 0.625 | 0.59 | 0.69 | 0.31 | 0.44 | SAE J483 |
| 1/2" | Low cap nuts | 13 | 0.75 | 0.72 | 0.81 | 0.38 | 0.5 | SAE J483 |
| 9/16" | Low cap nuts | 12 | 0.875 | 0.84 | 0.94 | 0.44 | 0.56 | SAE J483 |
| 5/8" | Low cap nuts | 11 | 0.938 | 0.91 | 1 | 0.47 | 0.62 | SAE J483 |
| 3/4" | Low cap nuts | 10 | 1.062 | 1.03 | 1.16 | 0.53 | 0.75 | SAE J483 |
| 7/8" | Low cap nuts | 9 | 1.25 | 1.22 | 1.36 | 0.62 | 0.88 | SAE J483 |
| 1" | Low cap nuts | 8 | 1.438 | 1.41 | 1.55 | 0.72 | 1 | SAE J483 |
| 1 1/8" | Low cap nuts | 7 | 1.625 | 1.59 | 1.75 | 0.81 | 1.12 | SAE J483 |
| 1 1/4" | Low cap nuts | 7 | 1.812 | 1.78 | 1.95 | 0.91 | 1.25 | SAE J483 |
| #6 | High cap nuts | 32 | 0.312 | 0.3 | 0.42 | 0.17 | 0.19 | SAE J483 |
| #8 | High cap nuts | 32 | 0.312 | 0.3 | 0.42 | 0.17 | 0.19 | SAE J483 |
| #10 | High cap nuts | 24 | 0.375 | 0.36 | 0.52 | 0.2 | 0.25 | SAE J483 |
| #12 | High cap nuts | 24 | 0.375 | 0.36 | 0.52 | 0.2 | 0.28 | SAE J483 |
| 1/4" | High cap nuts | 20 | 0.438 | 0.41 | 0.59 | 0.23 | 0.31 | SAE J483 |
| 5/16" | High cap nuts | 18 | 0.5 | 0.47 | 0.69 | 0.28 | 0.38 | SAE J483 |
| 3/8" | High cap nuts | 16 | 0.562 | 0.53 | 0.78 | 0.31 | 0.47 | SAE J483 |
| 7/16" | High cap nuts | 14 | 0.625 | 0.59 | 0.88 | 0.34 | 0.53 | SAE J483 |
| 1/2" | High cap nuts | 13 | 0.75 | 0.72 | 1.03 | 0.42 | 0.62 | SAE J483 |
| 9/16" | High cap nuts | 12 | 0.875 | 0.84 | 1.19 | 0.48 | 0.69 | SAE J483 |
| 5/8" | High cap nuts | 11 | 0.938 | 0.91 | 1.28 | 0.53 | 0.78 | SAE J483 |
| 3/4" | High cap nuts | 10 | 1.062 | 1.03 | 1.45 | 0.59 | 0.94 | SAE J483 |
| 7/8" | High cap nuts | 9 | 1.25 | 1.22 | 1.72 | 0.7 | 1.09 | SAE J483 |
| 1" | High cap nuts | 8 | 1.438 | 1.41 | 1.97 | 0.81 | 1.25 | SAE J483 |
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. Thread size is the obvious variable and rarely the interesting one — height for clearance, across-flats for the tool already in the cell, and the locking feature for the vibration actually present. Made by cold heading or tapping.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
