Key facts
Where to buy| Property | Value | Source |
|---|---|---|
| Composition | Chromium 17.5–19.5 %, nickel 8.0–10.5 %, carbon up to 0.07 % | ASTM A240/A240M Table 1 (UNS S30400) |
| Specs by temper | AMS 5513 annealed, 5910 ¼ H, 5911 ½ H, 5912 ¾ H, 5913 full hard | MIL-HDBK-5J, Table 2.7.1.0(b) footnote b |
| Allowables | The 301 table applies for those specifications | MIL-HDBK-5J, Table 2.7.1.0(b) footnote b |
| Welding rod | 308L, AWS A5.9 | AC 43.13-1B CHG 1, Table 4-15 |
| Class | Austenitic, nonmagnetic, 300 series | AC 43.13-1B par. 6-164b |
Design allowables — sheet and strip by temper (properties of AISI 301 table, applicable to 304)
0.187 in and under. MIL-HDBK-5J Table 2.7.1.0(b), L and LT as printed.
| Temper | Specification | Ftu L / LT, ksi | Fty L / LT, ksi | Fsu, ksi | Basis |
|---|---|---|---|---|---|
| Annealed | AMS 5513 | 73 / 75 | 26 / 30 | 50 | S |
| ¼ hard | AMS 5910 | 124 / 122 | 69 / 67 | 66 | A |
| ½ hard | AMS 5911 | 141 / 142 | 93 / 92 | 77 | A |
| ¾ hard | AMS 5912 | 157 / 163 | 118 / 113 | 88 | A |
| Full hard | AMS 5913 | 174 / 175 | 137 / 125 | 95 | A |
Properties of the 300-series alloys that the handbook ties to Table 2.7.1.0(b) by footnote. Fsu and Ftu: Table 2.7.1.0(b), p. 2-223; E 29.0 × 10³ ksi annealed (L and LT), falling to 26–28 ksi × 10³ in the hard tempers; density 0.286 lb/in³. Cold-worked tempers lose strength above 900 °F. Yield, particularly in compression, and longitudinal modulus can be raised appreciably by stress relieving at 500 to 800 °F. MIL-HDBK-5J (2003) is superseded by MMPDS.
Thicknesses and forms
Sheet and strip in the five tempers; design values to 0.187 in. Tube, bar and wire are common but are not detailed in the public documents used here.
Forming
Anneal for forming; hard tempers for strength. No public bend radius table for stainless; the drawing or SRM governs.
Stainless work-hardens as you form it and springs back more than carbon steel; plan the tooling accordingly.
Quick check
Which rod welds 304 stainless according to AC 43.13-1B?
- 4130 rod
Not this one. That welds mild and 4130 steel.
- 308L (AMS 5692)
Best fit. Right, Table 4-15.
- 4043
Not this one. 4043 is for aluminum.
On a real job, the SRM decides.
Welding
AISI 300-series austenitic steels are weldable with most processes except 303 and 303Se, which carry sulfur or selenium for machinability. They are slightly harder to weld than mild steel: lower melting temperature and conductivity, but higher expansion, so distortion needs skip or back-step welding, fixtures and twice the tack welds. Clean with a non-chlorinated solvent and a stainless wire brush; shield both sides with inert gas or flux (AMT Handbook, Chapter 5, p. 5-22).
AC 43.13-1B Table 4-15: 308L rod (AWS A5.9) welds 304 stainless.
Corrosion
Austenitic steels get their corrosion resistance from an oxide film that should not be removed even if the surface is discoloured. If the film is broken by abrasion it may not restore itself without repassivation. If corrosion affects the part's structural integrity or serviceability, the part is removed (AC 43.13-1B, par. 6-164b).
Where it is used on aircraft
General stainless fittings, ducts and brackets. MS20995 stainless safety wire is 302/304. Drawing and SRM name the alloy.
Data sheet
Questions people actually ask
What rod welds 304?
308L, AWS A5.9 (AC 43.13-1B Table 4-15).
Is 304 stronger than 301?
Not per the handbook: it applies the 301 table, and 301 is the one that work-hardens most.
Limits — when NOT to use this
- Values come from the 301 table by footnote.
- Not for firewalls or hot parts by default. Those call for the alloy on the drawing (321, 347, 301).
Where to buy
Distributors coming soon.
Sources
- MIL-HDBK-5J, Metallic Materials and Elements for Aerospace Vehicle Structures (31 Jan 2003) — Table 2.7.1.0(b), footnote b, p. 2-223. Cancelled; superseded by MMPDS.
- FAA AC 43.13-1B CHG 1 — Table 4-15 and par. 6-164.
- FAA-H-8083-31B, Aviation Maintenance Technician Handbook, Airframe, Volume 1 — Chapter 5, p. 5-22.
- MMPDS (formerly MIL-HDBK-5) — the current home of design allowables. A repair substantiation cites MMPDS or the SRM, not a website.
- ASTM A240/A240M, Plate, Sheet, and Strip of Chromium and Chromium-Nickel Stainless Steel — Table 1, chemical requirements (edition 10b read).