A182 F304 is the standard stainless steel forging grade, F304L is the low-carbon version suitable for welding, and F304H is the high-carbon version used for high-temperature and high-strength applications.
What is A182 Gr. F304 / F304L / F304H?
A182 Gr. F304, F304L, and F304H are forged stainless steel grades within the 304 series, used for manufacturing flanges, fittings, valve bodies, pressure-vessel components, and other parts that operate under high-temperature or high-pressure conditions. All three belong to the ASTM A182 standard.
The primary difference among them is carbon content, which determines weldability, resistance to intergranular corrosion, and high-temperature creep strength.
A182 Gr. F304 / F304L / F304H — Equivalent Materials
| Grade (ASTM A182) | F304 | F304L | F304H |
| UNS Number | S30400 | S30403 | S30409 |
| EN / DIN | 1.4301 | 1.4307 | ≈ 1.4948 |
| EN Name | X5CrNi18-10 | X2CrNi18-9 | X6CrNi18-11 |
| JIS | SUS304 | SUS304L | No exact JIS equivalent |
| GB (China) | 06Cr19Ni10 | 06Cr19Ni10 (Low C) | 10Cr19Ni10 |
| Typical ASTM Plate/Pipe | A240 304 / A312 TP304 | A240 304L / A312 TP304L | A240 304H / A312 TP304H |
| Notes | Standard 304 stainless steel | Low-carbon 304L for welding | High-carbon, high-temperature grade |
Chemical Composition
(Typical ranges, for reference only — exact values depend on ASTM A182)
| Identification Symbol | UNS | C | Mn | P | S | Si | Ni | Cr | N |
| F 304 | S30400 | 0.08 | 2 | 0.045 | 0.03 | 1 | 8.0–11.0 | 18.0–20.0 | ≤ 0.10 |
| F 304H | S30409 | 0.04–0.10 | 2 | 0.045 | 0.03 | 1 | 8.0–11.0 | 18.0–20.0 | … |
| F 304L | S30403 | 0.03 | 2 | 0.045 | 0.03 | 1 | 8.0–13.0 | 18.0–20.0 | 0.10–0.16 |
Mechanical Properties
(General reference for forged condition)
| Grade Symbol | Tensile Strength, min. | Yield Strength, min. | Elongation min. % | Reduction of Area min. % | Brinell Hardness HBW |
| F 304 | 75 ksi (515 MPa) | 30 ksi (205 MPa) | 30 | 50 | … |
| F 304H | 75 ksi (515 MPa) | 30 ksi (205 MPa) | 30 | 50 | … |
| F 304L | 70 ksi (485 MPa) | 25 ksi (170 MPa) | 30 | 50 | … |
Applications of A182 Gr. F304 / F304L / F304H
A182 F304 — General Purpose (Standard 304)
Suitable for medium-temperature, normal-pressure, or general corrosion-resistance conditions, including:
- Various flanges (WNRF / SORF / BLRF)
- Piping systems, fittings, valve components
- Food processing equipment
- Pharmaceutical industry equipment
- Chemical plants with mild corrosion (weak acids, weak alkalis)
- Heat exchanger shells, pump bodies, mechanical structures
Feature:
Balanced overall performance with the widest range of applications.
A182 F304L — Low Carbon, Welding-Optimized (Low-Carbon)
Ideal for conditions requiring extensive welding or enhanced resistance to intergranular corrosion:
- Pressure vessel welded systems
- Welded pipelines and welded flanges
- Oil & gas pipelines
- Chemical plants with chloride exposure
- Refrigeration equipment or low-temperature service (not cryogenic)
- LNG/LPG system pipelines at normal temperatures
Feature:
Does not easily develop intergranular corrosion after welding, ensuring long-term reliability.
A182 F304H — High-Temperature Strength Grade (High-Carbon)
Designed specifically for high-temperature environments:
- Boilers and furnace components
- High-temperature heat exchangers
- Heat-treatment furnace tubes, plates, and supports
- High-temperature steam piping
- Power-plant hot-section pipelines
- High-temperature pressure-vessel components
Feature:
Higher carbon content increases creep strength, making it suitable for continuous operation at 525–870°C.
Conclusion
A182 F304, F304L, and F304H belong to the same stainless steel family, yet each grade serves distinct performance needs:
- F304 for general use
- F304L for welding and corrosion resistance
- F304H for high-temperature strength
By understanding their differences in carbon content, welding behavior, and temperature resistance, engineers and buyers can choose the most suitable material for their application.
