304H is 304 stainless with carbon deliberately held at 0.04–0.10% (EN 1.4948, SUS 304H, GB 07Cr19Ni10) — the extra carbon raises creep and rupture strength so the grade keeps its code rating above ~500 °C. It is the specified grade for boilers, heat exchangers, superheaters and pressure vessels. Nikasteel supplies 304H plate and coil with EN 10204 3.1 MTC — MOQ 5 t, FOB/CIF.
Buyers who specify 304H are usually building something that gets hot and stays hot: boiler drums, superheater headers, heat exchanger shells, furnace internals. The chemistry is nearly identical to ordinary 304 — the difference is that carbon is a controlled minimum as well as maximum, and the material must be solution annealed with a coarse enough grain structure to deliver that strength in service.
304 vs 304L vs 304H — Choosing by Service Temperature
| Grade | Carbon | Strength Point | Watch Out | Typical Use |
|---|---|---|---|---|
| 304L (1.4307) | ≤ 0.03% | Welds thick sections without sensitization | Low creep strength — derates quickly above 400 °C | Welded tanks, chemical equipment below 400 °C |
| 304 (1.4301) | ≤ 0.08% | General-purpose balance | Neither best weldability nor best hot strength | Kitchen, architectural, general |
| 304H (1.4948) | 0.04–0.10% | Creep/rupture strength retained above 500 °C | Post-weld solution anneal for pressure service; min grain size 7 | Boilers, superheaters, HX, pressure vessels |
Equivalent Grades
| Standard | Designation |
|---|---|
| EN 10028-7 (vessel plate) / EN 10216-5 (tubes) | 1.4948 — X5CrNi18-10 |
| ASTM A240 (plate) / A312 (pipe), ASME II | 304H (UNS S30409) |
| JIS G4303 / G3459 | SUS 304H |
| GB/T 24511 (China) | 07Cr19Ni10 (old 0Cr19Ni10) |
Chemical Composition (ladle, %)
| C | Si | Mn | Cr | Ni | P | S | N |
|---|---|---|---|---|---|---|---|
| 0.04–0.10 | ≤ 0.75 | ≤ 2.00 | 17.5–19.5 | 8.0–10.5 | ≤ 0.040 (typ. ≤0.030) | ≤ 0.015 | ≤ 0.10 |
Mechanical Properties
| Property | Room Temp (EN 10028-7) | High-Temp Note |
|---|---|---|
| Yield Rp0.2 | ≥ 210 MPa | ≈ 120 MPa at 500 °C (vs ~70 MPa for 304L) |
| Tensile Rm | 520–670 MPa | creep rupture governed above 550 °C |
| Elongation A | ≥ 40% | — |
| Condition | Solution annealed 1040–1150 °C, rapid cool | min grain size 7 (ASTM E112) per H-grade requirement |
Typical Applications
- Boiler pressure parts, superheater and reheater tubes/headers
- Shell-and-tube heat exchangers handling hot process streams
- Petrochemical furnace coils and reformer fittings (with 321H/316H alternatives where design requires)
- Steam piping and ASME-code pressure vessels rated for sustained service 500–800 °C
Procurement Notes That Save Arguments Later
- Ask the mill for heat treatment certificates showing solution anneal temperature — H-grades are code-invalid without it.
- Check the MTC grain size line (ASTM E112 #7 or coarser); 304H without this check risks a rejected inspection.
- For welded pressure parts, order filler 308H/316H, not 308L, and anneal after welding per code.
- EN 10204 3.1 MTC comes standard from Nikasteel; 3.2 (third-party endorsed by TUV/BV) can be arranged for code projects.
Supply from Nikasteel
We supply 304H hot-rolled plate (3–100 mm), coil and sheet with solution-annealed condition and full 3.1 MTC listing chemistry, mechanicals, grain size and heat treatment. Recent shipments include 304H + 409L consolidated containers to Haiphong, Vietnam. Mixed grades, plasma/flame cut-to-size and third-party inspection welcome. Cross-standard stainless equivalents chart → · 409L exhaust grade →
Need 304H plate or coil with proper H-grade certificates?
Email [email protected] or WhatsApp +86 191 5745 8011 with thickness, size and code requirement — quotation within one working day, MOQ 5 tons.
Request a 304H Quotation