Grades 304 vs 304L Product Data Sheet

Grade 304L is used in welded sections of about 5mm and thicker. When comparing 304 vs 304L stainless steel, the lower carbon content (0.03% maximum) avoids the formation of coarse chromium carbide particles at grain boundaries due to extended times at elevated temperatures during welding. Grade 304 may suffer corrosion at grain boundaries due to sensitisation after welding at these gauges. Grade 304 is usually adequate at lighter gauges. There are several different national & international specifications for grade 304L. This note details some of these differences.

Country	Australia		USA		Japan		Europe
Specification	AS1449:1994		ASTM A240		JIS G4305		En10088-2:1995
Grade Name	304	304L	304	304L	304	304L	304	304L
			S30400	S30403			1.4301	1.4306
Chemistry %
Carbon	< 0.08	< 0.03	< 0.08	< 0.03	< 0.08	< 0.03	< 0.07	< 0.03
Nitrogen	–	< 0.10	< 0.10	< 0.10	–	–	< 0.11	< 0.11
Chromium	18.0-20.0	18.0-20.0	18.0-20.0	18.0-20.0	18.0-20.0	18.0-20.0	17.0-19.5	18.0-20.0
Nickel	8.0-10.5	8.0-12.0	8.0-10.5	8.0-12.0	8.0-10.5	9.0-13.0	8.0-10.5	10.0-12.0
Properties (min)
0.2% Proof Stress (MPa)	205	170	205	170	205	175	230	220
Tensile Strength (MPa)	520	485	515	485	520	480	540-750	520-670
Elongation (%)	40	40	40.0	40.0	40	40	45	45

 

This diagram (for grade 304) shows curves which separate the area to the left, where sensitisation is negligible, from that to the right of the curve, where sensitisation is present. It can be seen that the critical cooling rate to avoid sensitisation depends strongly on the carbon content.

The critical time to avoid sensitisation is slightly different for each grade, but the form of the effect is the same.

304 stainless steel has a range of applications across different industries. Brewing and dairy equipment, evaporators, drums, barrels, heat exchangers, hospital equipment, refrigeration parts, chemical and food processing, shop fittings, benchtops, kitchens, kitchen utensils, sinks, wash troughs, urinals, handrails, dishwashers, clothes dryers, ovens, heating trays, air conditioning equipment, guttering and rain water goods, counters and display cabinets, hot and cold food bars, commercial oven hoods, beer barrels.

 

Grade 304 stainless steel contains 18% chromium, which makes it resistant to many corrosive environments. It is austenitic in structure because of the 8% nickel it contains. The very tough and ductile austenitic structure gives grade 304 excellent formability and fabrication characteristics.

In most applications, 304 stainless steel is used where its corrosion resistance gives long-lasting appearance and service life. The ease of cleaning and of maintaining a hygienic surface on the steel make it excellent for many purposes.

The low carbon version, 304L stainless steel, may be required for full corrosion resistance when sections thicker than about 6mm are welded. The version with guaranteed high carbon, 304H stainless steel, may be required for elevated temperature service, such as pressure vessels.

 

304 grade stainless steel offers excellent corrosion resistance in a wide range of environments. GNEE is happy to provide advice for specific applications.

304 stainless steel performs well under general atmospheric conditions and can withstand most environments, except for marine environments or areas with heavy industrial pollution. Optimal appearance can be maintained if the design allows for even rinsing of the surface by rainwater or if dirt is regularly removed from the steel surface.

304 stainless steel performs well in some drinking water applications. However, pitting and crevice corrosion may occur in the presence of high chloride levels; 200 ppm is generally considered the upper limit for chloride content.

Due to its susceptibility to crevice corrosion under deposits, sediments, and biofouling, 304 grade stainless steel is generally not used in seawater environments.

 

 

We provide a comprehensive range of stainless steel grades, including the widely used 304 and 316 series, as well as specialized grades such as 430, 201, duplex, and super austenitic steels, tailored to meet diverse industrial and environmental requirements. Whether you need corrosion-resistant solutions for marine applications, food-grade compliance, high-temperature durability, or custom specifications, our expert team is ready to assist.

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Each batch of exported stainless steel products adheres to the most stringent testing standards: from spectral analysis of raw materials to ensure precise composition, to surface polishing precision inspection for mirror-like smoothness; from salt spray testing to verify corrosion resistance lifespan, to physical performance testing that guarantees strength and toughness. We possess a complete laboratory testing system and third-party authoritative certifications, ensuring every product not only complies with international ASTM, JIS, and EN standards but also delivers a "zero-defect" commitment, providing you with complete peace of mind throughout your procurement process.

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