Slotted Pan Head Machine Screws, UNC manufactured in A4 Stainless Steel (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80) are dimensioned to ASME B18.6.3. The sections below give the mechanical and physical properties of the grade, its behavior in corrosive and elevated-temperature service, and the full size table.
Why Choose A4 Stainless Steel for Slotted Pan Head Machine Screws, UNC
Specified for marine, coastal and chemical applications. For slotted pan head machine screws, unc, 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 Slotted Pan Head Machine Screws, UNC in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Comparable Grades
For Slotted Pan Head Machine Screws, UNC, 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 Slotted Pan Head Machine Screws, UNC Available in A4 Stainless Steel
| Size | Pitch P (in) | Head diameter dk (in) | Head height k (in) | R (in) | J (in) | T (in) | Length range l (in) | Reference standard |
|---|---|---|---|---|---|---|---|---|
| #0 | 0.013 | 0.116 | 0.039 | 0.02 | 0.023 | 0.022 | 1/16"~1 1/2" | ASME B18.6.3 |
| #1 | 0.016 | 0.142 | 0.046 | 0.025 | 0.026 | 0.027 | 1/16"~1 1/2" | ASME B18.6.3 |
| #2 | 0.018 | 0.167 | 0.053 | 0.035 | 0.031 | 0.031 | 1/16"~2 1/2" | ASME B18.6.3 |
| #3 | 0.021 | 0.193 | 0.06 | 0.037 | 0.035 | 0.036 | 1/8"~2 1/2" | ASME B18.6.3 |
| #4 | 0.025 | 0.219 | 0.068 | 0.042 | 0.039 | 0.04 | 1/8"~4" | ASME B18.6.3 |
| #5 | 0.025 | 0.245 | 0.075 | 0.044 | 0.043 | 0.045 | 3/16"~4" | ASME B18.6.3 |
| #6 | 0.031 | 0.27 | 0.082 | 0.046 | 0.048 | 0.05 | 1/8"~4" | ASME B18.6.3 |
| #8 | 0.031 | 0.322 | 0.096 | 0.052 | 0.054 | 0.058 | 1/8"~5" | ASME B18.6.3 |
| #10 | 0.042 | 0.373 | 0.11 | 0.061 | 0.06 | 0.068 | 3/16"~8" | ASME B18.6.3 |
| #12 | 0.042 | 0.425 | 0.125 | 0.078 | 0.067 | 0.077 | 1/4"~8" | ASME B18.6.3 |
| 1/4" | 0.05 | 0.492 | 0.144 | 0.087 | 0.075 | 0.087 | 3/8"~10" | ASME B18.6.3 |
| 5/16" | 0.056 | 0.615 | 0.178 | 0.099 | 0.084 | 0.106 | 1/2"~10" | ASME B18.6.3 |
| 3/8" | 0.062 | 0.74 | 0.212 | 0.143 | 0.094 | 0.124 | 1/2"~12" | ASME B18.6.3 |
| 7/16" | 0.071 | 0.863 | 0.247 | 0.153 | 0.094 | 0.142 | 3/4"~12" | ASME B18.6.3 |
| 1/2" | 0.077 | 0.987 | 0.281 | 0.175 | 0.106 | 0.161 | 3/4"~12" | ASME B18.6.3 |
| 9/16" | 0.083 | 1.041 | 0.315 | 0.197 | 0.118 | 0.179 | 3/4"~12" | ASME B18.6.3 |
| 5/8" | 0.091 | 1.172 | 0.35 | 0.219 | 0.133 | 0.197 | 3/4"~14" | ASME B18.6.3 |
| 3/4" | 0.1 | 1.435 | 0.419 | 0.263 | 0.149 | 0.234 | 1"~14" | 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.
