Type 304H is the high carbon version of 304 and 304L. T304H (high carbon) in a wide range of gauges and finishes. Type 304H has a carbon content between .04% and .10%
Grade 304H with its higher carbon content finds application at elevated temperatures. The austenitic structure also gives these grades excellent toughness, even down to cryogenic temperatures.
It is common for certifications of Grade 304H to be dual certified as 304/304H when the material has a higher carbon content.
These properties are specified for ASTM A240/A240M. Similar but not necessarily identical properties are specified for other products such as pipe and bar in their respective specifications.
Specifications
AMS 5513, ASME SA240, ASTM A240, ASTM A959, UNS S30400, UNS S30409
Composition
Grade | C | Mn | Si | P | S | Cr | Mo | Ni | N | |
304 | min.max. | -0.08 | -2.0 | -0.75 | -0.045 | -0.030 | 18.020.0 | - | 8.010.5 | -0.10 |
304L | min.max. | -0.030 | -2.0 | -0.75 | -0.045 | -0.030 | 18.020.0 | - | 8.012.0 | -0.10 |
304H | min.max. | 0.040.10 | -2.0 | -0.75 | -0.045 | -0.030 | 18.020.0 | - | 8.010.5 | - |
Grade | Tensile Strength (MPa) min | Yield Strength 0.2% Proof (MPa) min | Elongation (% in 50mm) min | Hardness | |
Rockwell B (HR B) max | Brinell (HB) max | ||||
304 | 515 | 205 | 40 | 92 | 201 |
304L | 485 | 170 | 40 | 92 | 201 |
304H | 515 | 205 | 40 | 92 | 201 |
304H also has a requirement for a grain size of ASTM No 7 or coarser. |
Grade | Density (kg/m3) | Elastic Modulus (GPa) | Mean Coefficient of Thermal Expansion (mm/m/°C) | Thermal Conductivity (W/m.K) | Specific Heat 0-100°C (J/kg.K) | Electrical Resistivity (nW.m) | |||
0-100°C | 0-315°C | 0-538°C | at 100°C | at 500°C | |||||
304/L/H | 8000 | 193 | 17.2 | 17.8 | 18.4 | 16.2 | 21.5 | 500 | 720 |
Grade | UNS No | Old British | Euronorm | Swedish SS | Japanese JIS | ||
BS | En | No | Name | ||||
304 | S30400 | 304S31 | 58E | 1.4301 | X5CrNi18-10 | 2332 | SUS 304 |
304L | S30403 | 304S11 | - | 1.4306 | X2CrNi19-11 | 2352 | SUS 304L |
304H | S30409 | 304S51 | - | 1.4948 | X6CrNi18-11 | - | - |
These comparisons are approximate only. The list is intended as a comparison of functionally similar materials not as a schedule of contractual equivalents. If exact equivalents are needed original specifications must be consulted. |
Applications:
Pressure vessels, petrochemical equipment, welded components or chemical,