What is the difference between 304 and 304L?

304L has less carbon (0.03% max). That keeps welded joints from losing corrosion resistance, which matters most on thick sections and corrosive service. Strength is a little lower.

Is most SS304 sheet actually dual certified?

Often yes. Many mills make material that meets both 304 and 304L limits and certify it as 304/304L. The mill test certificate shows the actual carbon content.

Should I use 304L or 316L for a food tank?

304L suits most dairy and food duty. Choose 316L where there are chlorides, salty products or strong cleaning chemicals.

SS304L stainless steel: properties, 304 vs 304L, uses

SS304L is the low-carbon version of SS304, with about 18% chromium and 8–12% nickel and 0.03% carbon max. The low carbon stops chromium carbides forming next to welds, so thick welded parts keep their corrosion resistance without annealing after welding. It is used for welded tanks, pipes, dairy and food equipment.

Quick facts

Type: Austenitic stainless steel
Carbon: 0.03% max (SS304: 0.07–0.08% max)
Corrosion: Like 304; better at welds in corrosive service
Hardening: Not hardenable by heat treatment; work-hardens
Magnetic: No (annealed); slightly after cold work
Weldability: Excellent

Equivalent grades

Standard	Grade
AISI / ASTM	304L
EN	1.4307 (X2CrNi18-9)
UNS	S30403
JIS	SUS304L

Equivalents are close, not identical. Name the grade and standard on the drawing.

Typical chemical composition

Element	%
Carbon (C)	0.03 max
Chromium (Cr)	About 17.5–20
Nickel (Ni)	About 8–12
Manganese (Mn)	Up to 2
Silicon (Si)	Up to 0.75–1

Values are typical. The exact limits depend on the standard and supplier; ask for the mill test certificate when it matters.

SS304 or SS304L?

	SS304	SS304L
Carbon	0.07–0.08% max	0.03% max
Thick welded parts	Risk of weld decay in some media	Keeps corrosion resistance at welds
Strength	Slightly higher	Slightly lower
Typical use	Sheet work, machined parts	Welded tanks, vessels, pipelines

Typical uses

Storage tanks and process vessels
Dairy, brewery and food equipment
Welded pipes and fittings
Heat exchanger tubes
Architectural and structural stainless work

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Questions

What is the difference between 304 and 304L?: 304L has less carbon (0.03% max). That keeps welded joints from losing corrosion resistance, which matters most on thick sections and corrosive service. Strength is a little lower.
Is most SS304 sheet actually dual certified?: Often yes. Many mills make material that meets both 304 and 304L limits and certify it as 304/304L. The mill test certificate shows the actual carbon content.
Should I use 304L or 316L for a food tank?: 304L suits most dairy and food duty. Choose 316L where there are chlorides, salty products or strong cleaning chemicals.

The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 18 October 2026.