Overview
Type 304L is a lower carbon variant of Grade 304 – the steel can be welded without the resulting issue of carbon precipitation (precipitation of chromium carbide as heat is applied during the welding process which depletes the chromium element of the steel thus reducing its anti-corrosive/oxidation effectiveness). As a result, Type 304L stainless steel is a sought after material for use in severely corrosive conditions. Weld annealing is only necessary in applications where stress loads are excessive.
Grade 304L, the low carbon version of 304, does not require post-weld annealing and so is extensively used in heavy gauge components (over about 6mm).
Specification
ASTM A213/A213M-21a Standard Specification for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes.
Chemical Composition
Grade | C | Mn | Si | P | S | Cr | Mo | Ni | N | |
304 | min. | - | - | - | - | - | 18.0 | - | 8.0 | - |
max. | 0.08 | 2.0 | 0.75 | 0.045 | 0.030 | 20.0 | 10.5 | 0.10 | ||
304L | min. | - | - | - | - | - | 18.0 | - | 8.0 | - |
max. | 0.030 | 2.0 | 0.75 | 0.045 | 0.030 | 20.0 | 12.0 | 0.10 | ||
304H | min. | 0.04 | - | - | - | - | 18.0 | - | 8.0 | - |
max. | 0.10 | 2.0 | 0.75 | 0.045 | 0.030 | 20.0 | 10.5 | |||
Mechanical Properties
Grade | Tensile Strength | Yield Strength | Elongation | Hardness | |
Rockwell B | Brinell | ||||
304 | 515 | 205 | 40 | 92 | 201 |
304L | 485 | 170 | 40 | 92 | 201 |
304H | 515 | 205 | 40 | 92 | 201 |
Physical Properties
| Grade | Density (kg/m3) | Elastic Modulus (GPa) | Mean Coefficient of Thermal Expansion (μm/m/°C) | Thermal Conductivity (W/m.K) | Specific Heat 0-100°C (J/kg.K) | Electrical Resistivity (nΩ.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 |
Applications
1. Food processing equipment, particularly in beer brewing, milk processing & wine making.
2. Kitchen benches, sinks, troughs, equipment and appliances
3. Architectural panelling, railings & trim
4. Chemical containers, including for transport
5. Heat Exchangers
6. Woven or welded screens for mining, quarrying & water filtration
7. Threaded fasteners
8. Springs
