304 Stainless Fasteners
304 is the common austenitic stainless alloy: about 18% chromium and 8% nickel. It resists general corrosion well but is not the first choice in salt water.
Chemistry (typical)
| Alloy | Chromium | Nickel | Molybdenum | Best for |
|---|---|---|---|---|
| 304 | 18 - 20% | 8 - 10.5% | - | General corrosion resistance |
| 316 | 16 - 18% | 10 - 14% | 2 - 3% | Chlorides, marine, chemical |
Strength by specification
| Specification | Class / condition | Tensile (min) |
|---|---|---|
| ASTM F593 Group 1 | CW1, 1/4 - 5/8 in | 100 ksi |
| ASTM F593 Group 1 | CW2, 3/4 - 1-1/2 in | 85 ksi |
| ISO 3506 | A2-70 | 700 MPa |
These tables carry the same figures as the printed sheet below.
The printed sheet
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Text version of this sheet
Alloy 304 · austenitic stainless · 18-8 family
What it is
FIELD IDENTIFICATION
304 is the common austenitic stainless alloy: about 18% chromium and 8% nickel. It resists general
corrosion well but is not the first choice in salt water.
MFG
304*
Alloy/condition marking varies
Chemistry (typical)
Alloy
Chromium
Nickel
Molybdenum
Best for
304
18 - 20%
8 - 10.5%
-
General corrosion resistance
316
16 - 18%
10 - 14%
2 - 3%
Chlorides, marine, chemical
Strength by specification
Specification
Class / condition
Tensile (min)
ASTM F593 Group 1
CW1, 1/4 - 5/8 in
100 ksi
ASTM F593 Group 1
CW2, 3/4 - 1-1/2 in
85 ksi
A2-70
700 MPa
ISO 3506
Key points
"304" on a box is an alloy name. It is not F593 or ISO 3506 certification.
Non-magnetic when annealed; cold work can make it slightly magnetic. A magnet is not a reliable alloy test.
"316" or "304" on a head is an alloy mark, not a manufacturer logo and not a strength grade.
Governing standards: ASTM F593-24; ASTM F594-24 (nuts); ISO 3506-1/-2:2020. Editions shown are the latest confirmed as of September 2026. The drawing and the governing
standard always take precedence over this sheet.
torquing any fastener. Verify the current governing standard, project documents, OEM requirements, size, thread, coating and lot certification. To the fullest extent permitted by law, The Fastener App disclaims liability
arising from reliance on this reference.
Fastener Guide reference FG-F73F65 · thefastenerapp.com/fastener-guide/technical-reference/304-stainless-fasteners · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.
