Is 1.4301 stainless steel 304 or 304L?

1.4301 is an austenitic stainless steel grade (X5CrNi18-10) in the EU EN standard. Its chemical composition is exactly the same as the 304 stainless steel (UNS S30400) in the US ASTM standard, but it is significantly different from 304L stainless steel (UNS S30403). The following is the core correspondence between the three:

Standard System Comparison Table for 1.4301, 304, and 304L Stainless Steels

Key Notes:
1.4301 is the European EN-standard equivalent of 304 stainless steel (ASTM S30400).
304L (ASTM S30403) is a low-carbon variant of 304, with ≤0.03% carbon to minimize intergranular corrosion after welding. 

Corrosion resistance
1.4301/304: Excellent performance in conventional environments (such as atmosphere, fresh water, food contact), and the salt spray corrosion resistance time can reach more than 500 hours.
304L: The corrosion resistance is more stable after welding, especially suitable for scenes that require frequent welding such as chemical equipment and pressure vessels. For example, 304L is used for battery coolant pipelines in Tesla's super factory and is resistant to hydrofluoric acid (HF) corrosion.
Mechanical properties
Strength: The yield strength of 304 is 205MPa, and that of 304L is 170MPa, but 304L can be increased to 520MPa through cold working.
Processability: The cold work hardening index (n=0.30) of 304 is slightly lower than that of 304L (n=0.35), which is more suitable for complex stamping.
Welding performance
304: Solution treatment (1040-1150℃) is required after welding to eliminate the risk of intergranular corrosion and increase the complexity of the process.
304L: Its low carbon properties allow it to maintain corrosion resistance without heat treatment after welding, reducing welding costs by 20%.