A2 Stainless Steel (ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70) is the most common stainless group for indoor and general outdoor fasteners. When inch hex-socket shoulder screws are specified in this grade, the dimensions remain per ASME B18.3; the material determines corrosion behavior (good general corrosion resistance) 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 A2 Stainless Steel for Inch Hex-Socket Shoulder Screws
The most common stainless group for indoor and general outdoor fasteners. For inch hex-socket shoulder screws, this matters when good general corrosion resistance is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70 |
|---|---|
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C, subject to the property class and the joint |
| Corrosion characteristic | Good general corrosion resistance |
Galvanic & Galling Considerations
Two important notes for stainless inch hex-socket shoulder screws: (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 Inch Hex-Socket Shoulder Screws, the alternative stainless grade is A4 (316). 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
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 Inch Hex-Socket Shoulder Screws Available in A2 Stainless Steel
| Shoulder diameter (in) | Shoulder length (in) | Hex socket across-flats (in) | Thread series | Material options | Reference standard |
|---|---|---|---|---|---|
| 1/8 | 1/8~1-1/2 | 5/64~1/4 | #4-40 through #10-32 | alloy steel / 303-316 stainless / 416 stainless / brass | ASME B18.3 |
| 1/4 | 1/8~1-1/2 | 5/64~1/4 | #4-40 through 1/4-20 | alloy steel / 303-316 stainless / 416 stainless / brass | ASME B18.3 |
| 1/2 | 1/8~1-1/2 | 5/64~1/4 | #4-40 through 3/8-16 | alloy steel / 303-316 stainless / 416 stainless / brass | ASME B18.3 |
| 3/4 | 1/8~1-1/2 | 5/64~1/4 | 1/4-20 through 1/2-13 | alloy steel / 303-316 stainless / 416 stainless / brass | ASME B18.3 |
Dimensions are independent of the material: every size above is available in A2 Stainless Steel.
Custom manufacturing · Made to drawing
Need this bolt in a grade that is not listed?
A2 Stainless Steel is one of the grades the catalog describes. Where the standard stops, the drawing takes over: fine pitches, left-hand threads, partial threading, and property classes above the catalogued grade where material and heat treatment allow. Made by cold heading or hot forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
