Our cold-rolled tempered stainless — Quarter Hard, Half Hard and Full Hard — is listed as 302 / 304 for the same reason our annealed material is triple certified: it is one material, certified to both alloys at once.
A temper is not a different alloy
A temper is the same 302 / 304 chemistry, cold rolled after annealing to raise its strength. The more the material is reduced, the harder the temper. Because we buy to an overlapping chemistry that sits inside both the 302 and 304 limits, the finished coil can be certified to the 302 temper specification and the 304 temper specification at the same time.
Temper is proven by testing
Chemistry says what the material is; mechanical testing proves its temper. At each temper, the tensile and yield minimums are the same for both types — so material that passes the test satisfies whichever type your drawing or purchase order calls out.
Temper Specifications & Strength Minimums
| Temper | Type 302UNS S30200 | Type 304UNS S30400 | MinimumsTensile / Yield, psi |
|---|---|---|---|
| Quarter Hard | AMS 5903 ASTM A666 | AMS 5910 ASTM A666 | 125,000 75,000 |
| Half Hard | AMS 5904 ASTM A666 | AMS 5911 ASTM A666 | 150,000 110,000 |
| Full Hard | AMS 5906 ASTM A666 | AMS 5913 AMS only — see note | 185,000 140,000 |
Note on 304 Full Hard: ASTM A666 covers the Three-Quarter Hard and Full Hard tempers for Types 301 and 302 only — Type 304 is not listed in ASTM A666 at Full Hard. 304 Full Hard is therefore certified to AMS 5913 rather than ASTM A666.
The chemistry overlap
Where the two alloys’ limits differ, the tighter limit wins: carbon to 304’s 0.08% maximum, chromium to the 18.0–19.0% band the two ranges share, and nickel to 302’s 10.0% ceiling. Temper doesn’t change any of these values — cold rolling changes strength, not chemistry.
Chemical Requirements — Type 302 & 304 (weight %)
| Element | 302UNS S30200 | 304UNS S30400 | Dual-CertifiedOverlap Range |
|---|---|---|---|
| Carbon (C) | 0.15 max | 0.08 max | 0.08 max |
| Manganese (Mn) | 2.00 max | 2.00 max | 2.00 max |
| Silicon (Si) | 0.75 max | 0.75 max | 0.75 max |
| Phosphorus (P) | 0.045 max | 0.045 max | 0.045 max |
| Sulfur (S) | 0.030 max | 0.030 max | 0.030 max |
| Chromium (Cr) | 17.0–19.0 | 18.0–20.0 | 18.0–19.0 |
| Nickel (Ni) | 8.0–10.0 | 8.0–10.5 | 8.0–10.0 |
| Nitrogen (N) | 0.10 max | 0.10 max | 0.10 max |
| Iron (Fe) | Balance | Balance | Balance |
Some AMS editions permit silicon to 1.00% max; the ASTM A666 limit of 0.75% max is shown because it governs.
What it means on your paperwork
A purchase order that calls out 302 or 304 in Quarter, Half or Full Hard can be filled from the same dual-certified material, and the mill test report and certificate of conformance show the alloys and specifications it meets.
Values shown are specification limits, not a mill analysis — actual chemistry and test results appear on the certified mill test report supplied with your order. Minimum elongation varies by type and thickness and is stated on the mill certificate. This article is educational information only; always order to the current revision of the governing specification.