Type 304 (S30400), Type 304L (S30403)

Type 304/304L is the modern version of "18-8" stainless steel containing approximately 18% chromium and 8% nickel and is the most commonly specified stainless steel used throughout the world. Type 304/304L is a versatile, general purpose stainless steel with good resistance to atmospheric corrosion, and to many chemicals and food and beverages. These grades can be specified in the annealed condition where they have very good formability. Higher nickel versions can be specified to enhance multi-stage deep drawing characteristics. Higher strength, cold-worked conditions can also be specified for Type 304/304L for spring type applications. Type 304/304L is non-magnetic in the annealed condition but may become slightly magnetic as a result of cold working.

Type 304L can be dual certified as 304 when the composition meets the lower carbon limit of 304L and the slightly higher strength levels of 304. Type 304L should be specified for welded applications as the low carbon version eliminates chromium carbide precipitation and enhances the corrosion resistance in the as-welded condition.

 

Chemical Composition (wt%) limits as specified in ASTM A240 and ASME SA240*

Element	304	304L
Carbon	0.07	0.03 max
Chromium	17.5-19.5	17.5-19.5
Nickel	8.0-10.5	8.0-12.0
Manganese	2.00	2.00
Silicon	0.75	0.75
Nitrogen	0.10	0.10
Phosphorus	0.045	0.045
Sulfur	0.030	0.030

 

Mechanical property requirements for annealed product as specified in ASTM A240 and ASME SA240

Property	304	304L
Yield Strength, min. (ksi)	30	25
Tensile Strength, min. (ksi)	75	70
Elongation, min. (%)	40	40
Hardness, max. (Rb)	92	92

 

Physical properties for Type 304/304L stainless steel

Property	304/304LData
Density, lb/in3	0.285
Modulus of Elasticity, psi	28 x 106
Coefficient of Thermal Expansion, 68-212˚F, /˚F	9.2 x 10-6
Thermal Conductivity, Btu/ft hr ˚F	9.4
Specific Heat, Btu/lb ˚F	0.12
Electrical Resistivity, Microohm-in	28.3

 

Typical standards for Type 304/304L stainless steel

304	304L
ASTM A240	ASTM A240
ASTM A666	ASTM A666
ASME SA240	ASME SA240
AMS 5513	AMS 5511

 

Q1: What is the main difference between 304 and 304L stainless steel?
A: The main difference is the carbon content. 304 stainless steel contains up to 0.08% carbon, while 304L stainless steel contains a maximum of 0.03% carbon. This lower carbon content in 304L significantly improves its resistance to weld decay.

Q2: Is 304 stronger than 304L stainless steel?
A: At room temperature, 304 and 304L stainless steel have very similar strength. The main mechanical difference is that 304 stainless steel generally has slightly higher strength at elevated temperatures compared to 304L stainless steel.

Q3: When should I choose 304L over 304 stainless steel?
A: Choose 304L stainless steel over 304 stainless steel when the component will be heavily welded and used in a corrosive environment without subsequent heat treatment. 304L stainless steel is also specified for certain chemical processing and food industry applications.

Q4: When is standard 304 better than 304L stainless steel?
A: Standard 304 stainless steel is a better choice than 304L stainless steel for applications that require high-temperature strength or for parts that will be fully heat-treated (annealed) after welding to restore corrosion resistance.

 

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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