Sep 12, 2026Procurement Guides
Physical Properties of 304 Stainless Steel: What Designers Need
Type 304 is an 18/8 austenitic stainless steel with about 8 g/cm3 density and good corrosion, formability and weldability. Compare 304, 304L and 304H.
Quick answer: type 304 is an austenitic chromium-nickel stainless steel, commonly referred to as 18/8 because it contains roughly 18 percent chromium and 8 percent nickel. Its density is about 8 g/cm3 (0.289 lb/in3), it is non-magnetic in the annealed condition, and it offers a good balance of corrosion resistance, formability, weldability and strength at moderate cost. The main variants are 304, 304L (maximum 0.03 percent carbon) and 304H (0.04 to 0.10 percent carbon), and designers choose between them based on welding and high-temperature service.
What Type 304 Stainless Steel Is
The 3xx family of stainless steels is built on chromium and nickel. Type 304 is one of the most widely used austenitic grades. Its austenitic structure, a face-centered cubic arrangement of the iron-chromium-nickel alloy, gives it the combination of ductility, toughness and corrosion resistance that makes it a default choice for general service. The AISI and SAE naming systems both describe these alloys, which is why the same chemistry may appear under more than one identifier; the composition, not the label, defines the material.
Key Physical Properties of 304
The density of 304 stainless steel is about 8.0 g/cm3, or 0.289 lb/in3, which is close to that of carbon steel and slightly higher than many aluminium alloys. Typical room-temperature properties include a modulus of elasticity of roughly 193 to 200 GPa, thermal conductivity of about 16 W/m-K, and a mean coefficient of thermal expansion of roughly 17 x 10-6 per degree C over the range 0 to 100C. The melting range is typically about 1400C to 1450C. These values are typical for the annealed condition and should be confirmed against the mill certificate for critical design work.
One property that often matters more than designers expect is magnetic response. Annealed 304 is generally non-magnetic, but cold working such as bending, drawing or machining can form small amounts of martensite and make the material slightly magnetic. If a project requires strictly non-magnetic behaviour, that should be stated on the enquiry.
304 vs 304L vs 304H
The three main variants differ mainly in carbon content. Standard 304 has a maximum carbon content of 0.08 percent. 304L has a maximum of 0.03 percent, which raises ductility and makes it the usual choice for large welded assemblies that will not be solution annealed after welding, because low carbon reduces the risk of sensitization and intergranular corrosion. 304H has a carbon content of 0.04 to 0.10 percent, which supports strength retention at elevated temperature and makes it suitable for high-temperature service where creep and long-term strength matter.
Mechanical Behaviour, Formability and Weldability
Type 304 work-hardens readily, which is why it can be stretched, formed and drawn into complex shapes. It welds well by most common processes, with or without filler, and it is used in a wide range of fabricated products. The low carbon content of austenitic grades generally keeps them tough, and in the low-carbon variants nitrogen can be controlled to maintain strength. Designers should still account for the strength increase caused by cold working, because formed or drawn parts are stronger and less ductile than the starting sheet.
Corrosion Resistance and Temperature Limits
Type 304 resists atmospheric corrosion and many mildly corrosive media, and it performs well in many food, dairy, water and architectural applications. It is not the best choice for chloride-rich environments, where pitting and crevice corrosion can occur and where a molybdenum-bearing grade such as 316 is commonly preferred. For continuous high-temperature service, the carbon content and the specific grade matter, and 304H is commonly selected where long-term elevated-temperature strength is required.
Design and Specification Notes
When specifying 304, state the product form, the variant (304, 304L or 304H), the condition (annealed, cold worked or as-welded), the finish, and the applicable standard such as ASTM or ASME. On the enquiry, include the required tolerances, test certificates and any non-magnetic requirement. Third-party inspection through SGS, BV, TUV or TUBOSCOPE can be arranged where the project requires it.
A grade name alone does not define performance. Carbon level, condition, finish and the service environment decide whether 304, 304L or 304H is the right choice.
How SPAI STEEL Supports Stainless Projects
SPAI STEEL, operated by Hunan Spai Pipe Industry Co., Ltd under SP Group, has supplied pipe and stainless products since 1996 and exports to more than 100 countries. Stainless and alloy production is based in Wenzhou Longwan, and the company works to GB, API, ASTM, ASME/ANSI, BS, DIN, JIS and GOST standards across ERW pipe, seamless pipe, LSAW and SSAW pipe, fittings and flanges, structural sections and stainless and alloy pipe.
FAQ
Is 304 stainless steel magnetic?
Annealed 304 is generally non-magnetic, but cold working can make it slightly magnetic. If a strictly non-magnetic condition is required, specify it clearly and confirm the delivered condition.
What is the density of 304 stainless steel?
The density is about 8.0 g/cm3, or 0.289 lb/in3, which is similar to carbon steel.
When should 304L be used instead of 304?
304L is normally chosen for large welded parts that will not be annealed after welding, because its lower carbon content reduces the risk of sensitization and intergranular corrosion.
Can 304 be used at high temperature?
Yes, within its limits. For long-term elevated-temperature service, 304H with its higher carbon content is commonly selected for better strength retention.
Send your grade, size, condition and service environment to our engineering team for a confirmed stainless pipe and tube recommendation.
