What is 1.4307 Stainless Steel?

1.4307 stainless steel, commonly known as 304L or UNS S30403, is the low-carbon version of the ubiquitous 304 austenitic stainless steel. By reducing the maximum carbon content, it provides excellent resistance to intergranular corrosion in the as-welded condition, making it the preferred choice for heavy welded fabrications, such as tanks, pipelines, and structural components in the chemical, food, and architectural industries.

 

This low-carbon variant is standardized under all major international systems.

	1.4307
	304L, UNS S30403
	SUS304L
	STS304L

The key differentiating element is its strictly controlled low carbon content.

	C			P	S
	<= 0.03	<= 1.0	<= 2.0	<= 0.045	<= 0.03	17.5 - 19.5	8.0 - 10.5

 

Its mechanical properties are very similar to standard 304, with excellent ductility.

	Yield Strength (Rp0.2)
	>= 180 MPa	490 - 690 MPa	>= 40%	<= 215

Key Characteristics and Applications of 1.4307 / 304L

The low carbon content minimizes the formation of chromium carbides in the heat-affected zone during welding, preventing the depletion of chromium and thus maintaining corrosion resistance without the need for post-weld heat treatment.

Retains the excellent all-around corrosion resistance of the 304 family against a wide range of atmospheric, chemical, and food industry environments.

 

Maintains the high ductility and formability characteristic of austenitic stainless steels, suitable for deep drawing, bending, and spinning.

Large storage tanks, pressure vessels, and process piping systems in chemical and petrochemical plants.

Welded vats, fermentation tanks, and conveyor systems where sanitization is critical.

Welded façades, railings, and structures in corrosive atmospheres.

Tubing and plates in applications where welding is extensive.

 

When should I choose 304L (1.4307) over standard 304 (1.4301)?
The primary rule is to choose 304L when the component will be heavily welded and cannot be subsequently heat treated (annealed) to dissolve harmful chromium carbides. For thin sections or applications with minimal welding, standard 304 is often sufficient and cost-effective. 304L is also mandated for service in the "sensitization" temperature range (450-850℃) where standard 304 would suffer from intergranular corrosion.

 

Does 304L have lower strength than 304 due to its lower carbon content?
In practice, the difference in room temperature mechanical strength between annealed 304 and 304L is very small and often within the specification overlap. Both grades meet similar minimum strength requirements. The lower carbon content primarily affects the material's behavior after exposure to high temperatures (like welding), not its ambient strength in the supplied condition.

 

Looking for a Reliable Supplier of 1.4307 / 304L Stainless Steel?
GNEE Steel stocks extensive quantities of versatile 304L (1.4307) stainless steel in all forms-plate, sheet, coil, pipe, and bar-perfect for welded fabrication projects. We provide full material certification and processing services. If you have any requirements, please feel free to contact us