A4 Stainless Steel (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80) is specified for marine, coastal and chemical applications. When fillister head machine screws, unc (slotted and phillips) are specified in this grade, the dimensions remain per ASME B18.6.3; 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 Fillister Head Machine Screws, UNC (Slotted and Phillips)
Specified for marine, coastal and chemical applications. For fillister head machine screws, unc (slotted and phillips), 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 fillister head machine screws, unc (slotted and phillips): (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 Fillister Head Machine Screws, UNC (Slotted and Phillips), 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
Expect the aluminum to corrode, not the fastener — stainless sits higher in the galvanic series, so the aluminum is the one that gives up material. A small fastener in a thick section spreads the loss over a large area and is usually fine; a large fastener in thin sheet concentrates it and is not. Keep water out of the joint, or isolate the two metals with a nylon or coated washer and a sealant.
Sizes of Fillister Head Machine Screws, UNC (Slotted and Phillips) Available in A4 Stainless Steel
| Size | Type | Pitch P (in) | Head diameter dk (in) | Head height k (in) | O (in) | J (in) | T (in) | Length range l (in) | Reference standard |
|---|---|---|---|---|---|---|---|---|---|
| #0 | Cross recessed fillister head screws | 0.013 | 0.096 | 0.043 | 0.055 | 0.023 | 0.025 | 1/16"~1 1/2" | ASME B18.6.3 |
| #0 | Slotted fillister head screws | 0.013 | 0.096 | 0.043 | 0.055 | 0.023 | 0.025 | 1/16"~1 1/2" | ASME B18.6.3 |
| #1 | Cross recessed fillister head screws | 0.016 | 0.118 | 0.053 | 0.066 | 0.026 | 0.031 | 1/16"~1 1/2" | ASME B18.6.3 |
| #1 | Slotted fillister head screws | 0.016 | 0.118 | 0.053 | 0.066 | 0.026 | 0.031 | 1/16"~1 1/2" | ASME B18.6.3 |
| #2 | Cross recessed fillister head screws | 0.018 | 0.14 | 0.062 | 0.083 | 0.031 | 0.037 | 1/16"~2 1/2" | ASME B18.6.3 |
| #2 | Slotted fillister head screws | 0.018 | 0.14 | 0.062 | 0.083 | 0.031 | 0.037 | 1/16"~2 1/2" | ASME B18.6.3 |
| #3 | Cross recessed fillister head screws | 0.021 | 0.161 | 0.07 | 0.095 | 0.035 | 0.043 | 1/8"~2 1/2" | ASME B18.6.3 |
| #3 | Slotted fillister head screws | 0.021 | 0.161 | 0.07 | 0.095 | 0.035 | 0.043 | 1/8"~2 1/2" | ASME B18.6.3 |
| #4 | Cross recessed fillister head screws | 0.025 | 0.183 | 0.079 | 0.107 | 0.039 | 0.048 | 1/8"~4" | ASME B18.6.3 |
| #4 | Slotted fillister head screws | 0.025 | 0.183 | 0.079 | 0.107 | 0.039 | 0.048 | 1/8"~4" | ASME B18.6.3 |
| #5 | Cross recessed fillister head screws | 0.025 | 0.205 | 0.088 | 0.12 | 0.043 | 0.054 | 3/16"~4" | ASME B18.6.3 |
| #5 | Slotted fillister head screws | 0.025 | 0.205 | 0.088 | 0.12 | 0.043 | 0.054 | 3/16"~4" | ASME B18.6.3 |
| #6 | Cross recessed fillister head screws | 0.031 | 0.226 | 0.096 | 0.132 | 0.048 | 0.06 | 1/8"~4" | ASME B18.6.3 |
| #6 | Slotted fillister head screws | 0.031 | 0.226 | 0.096 | 0.132 | 0.048 | 0.06 | 1/8"~4" | ASME B18.6.3 |
| #8 | Cross recessed fillister head screws | 0.031 | 0.27 | 0.113 | 0.156 | 0.054 | 0.071 | 1/8"~5" | ASME B18.6.3 |
| #8 | Slotted fillister head screws | 0.031 | 0.27 | 0.113 | 0.156 | 0.054 | 0.071 | 1/8"~5" | ASME B18.6.3 |
| #10 | Cross recessed fillister head screws | 0.042 | 0.313 | 0.13 | 0.18 | 0.06 | 0.083 | 3/16"~8" | ASME B18.6.3 |
| #10 | Slotted fillister head screws | 0.042 | 0.313 | 0.13 | 0.18 | 0.06 | 0.083 | 3/16"~8" | ASME B18.6.3 |
| #12 | Cross recessed fillister head screws | 0.042 | 0.357 | 0.148 | 0.205 | 0.067 | 0.094 | 1/4"~8" | ASME B18.6.3 |
| #12 | Slotted fillister head screws | 0.042 | 0.357 | 0.148 | 0.205 | 0.067 | 0.094 | 1/4"~8" | ASME B18.6.3 |
| 1/4" | Cross recessed fillister head screws | 0.05 | 0.414 | 0.17 | 0.237 | 0.075 | 0.109 | 3/8"~10" | ASME B18.6.3 |
| 1/4" | Slotted fillister head screws | 0.05 | 0.414 | 0.17 | 0.237 | 0.075 | 0.109 | 3/8"~10" | ASME B18.6.3 |
| 5/16" | Cross recessed fillister head screws | 0.056 | 0.518 | 0.211 | 0.295 | 0.084 | 0.137 | 1/2"~10" | ASME B18.6.3 |
| 5/16" | Slotted fillister head screws | 0.056 | 0.518 | 0.211 | 0.295 | 0.084 | 0.137 | 1/2"~10" | ASME B18.6.3 |
| 3/8" | Cross recessed fillister head screws | 0.062 | 0.622 | 0.253 | 0.355 | 0.094 | 0.164 | 1/2"~12" | ASME B18.6.3 |
| 3/8" | Slotted fillister head screws | 0.062 | 0.622 | 0.253 | 0.355 | 0.094 | 0.164 | 1/2"~12" | ASME B18.6.3 |
| 7/16" | Cross recessed fillister head screws | 0.071 | 0.625 | 0.265 | 0.368 | 0.094 | 0.17 | 3/4"~12" | ASME B18.6.3 |
| 7/16" | Slotted fillister head screws | 0.071 | 0.625 | 0.265 | 0.368 | 0.094 | 0.17 | 3/4"~12" | ASME B18.6.3 |
| 1/2" | Cross recessed fillister head screws | 0.077 | 0.75 | 0.297 | 0.412 | 0.106 | 0.19 | 3/4"~12" | ASME B18.6.3 |
| 1/2" | Slotted fillister head screws | 0.077 | 0.75 | 0.297 | 0.412 | 0.106 | 0.19 | 3/4"~12" | ASME B18.6.3 |
Dimensions are independent of the material: every size above is available in A4 Stainless Steel.
Custom manufacturing · Made to drawing
Need this screw in a grade that is not listed?
A4 Stainless Steel is one of the grades the catalog describes. Thread size and pitch, length, property class, drive form, head geometry and head marking are all specifiable — the standard part is where it starts, not where it stops. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.

