304 stainless steel properties. Sometimes referred to as 18/8 steel, 304 stainless steel is the most commonly used stainless steel in manufacturing. Chances are that you will have interacted with something made from 304 stainless steel in your daily routine. The biggest breakthrough in the use of stainless steel came in 1912 when engineers Eduard Maurer and Benno Strauss realized the value of chrome-nickel steel. But what makes it so popular, what are 304 stainless steel properties?
What is 304 stainless steel?
The steel patented by Eduard Maurer and Benno Strauss is known as austenitic steel. This steel makes up the vast majority of stainless steel production in the world (around 70%) and of this total stainless steel production, 304 stainless steel makes up the majority. In it’s simplest terms, 304 steel is 18% chromium and 8% nickel, hence 18/8 steel.
The exact composition of SAE 304 steel was developed by W. H. Hatfield at Firth-Vickers in 1924 and was marketed under the trade name “Staybrite 18/8”.
Type 304 stainless steel has good forming and welding properties as well as strong corrosion resistance and strength. You can find out more in our 304 stainless steel data sheet.
Properties and usage
Corrosion Resistance
304 steel has very good resistance to corrosion in many (non-specialist) environments, it is able to resist corrosion when in contact with a wide range of corrosive substances. Though it is not completely corrosion resistant; pitting and crevice corrosion will occur in environments which contain, for instance, chlorides and stress corrosion cracking can occur to some degree in temperatures above 60°C.
304 is considered to be resistant to potable water with up to about 200 mg/L chlorides at ambient temperatures, reducing to about 150 mg/L at 60 °C.
When 304 is considered too susceptible to corrosion it is preferable to use 316 stainless steel instead.
Heat Resistance
Type 304 has very good resistance to oxidation for temperatures up to 870°C in intermittent service and up to 925°C when in continuous service. But it is not recommended to be used when temperatures range between 425 – 860°C. This is when 304L (the lower carbon version of 304) is preferable, due to the far better resistance to carbide precipitation. When higher temperatures are expected, then yet another version of 304 is used, in this case, 304H.
Cost
Even with 304 Stainless steel properties, it costs the same as 302 but with all the extra benefits.
Advantages in outdoor applications
The key to 304 stainless steel’s success, particularly in outdoor applications, is the high nickel count. Any stainless steel which is high in nickel will resist stress-corrosion cracking better than other types of stainless steel. The higher count of nickel means that 304 is not magnetic and will resist iron oxide, making it ideal for application in the great outdoors, such as in architectural trims and even the humble barbecue.
Weldability
304 stainless steel has excellent fusion welding performance, with and without fillers. When using filler rods and electrodes it is recommended to use 308 stainless steel. Any heavy sections may require post-welding annealing.
Heat Treatment
It is not recommended to heat treat 304 for hardening. It can, however, be annealed or solution treatment carried out by rapid cooling after heating to 1010- 1120°C.
Hot Working
Methods of fabrication such as forging should be used after uniform heating to 1149-1260°C. It is also worth noting that in order to achieve the best possible corrosion resistance, 304 should be rapidly cooled after the heating process.
Cold Working
The steel will readily work harden, for that reason fabrication methods involving cold working may require an intermediate annealing stage. This is done to alleviate work hardening and therefore avoid any tearing or cracking. It is also recommended that after the completion of fabrication, a full annealing operation must be carried out to reduce any internal stresses and to optimize the corrosion resistance.
Fabrication
Any fabrication carried out using 304 stainless steel should only ever be carried out with tools dedicated to stainless steel materials. It is important to clean all surfaces before use. The reason for taking these precautions is simple; to reduce cross-contamination of the stainless steel with other, easily corroded, metals.
Machinability
One of the reasons that 304 steel is so popular is because it has good machinability. Cutting edges must be sharp and kept sharp, dull edges will cause excess work hardening. Cuts need to be light but deep enough to prevent work hardening. Coolants and lubricants are a necessity when working with 304 in any of its variations.
Applications
- Auto moldings and trim
- Wheel covers
- Storage Tanks
- Kitchen equipment/appliances
- Electrical enclosures
- Kitchen benches, sinks, troughs, equipment, and appliances
- Chemical containers, including for transport
- Food processing equipment, particularly in beer brewing, milk processing, and winemaking
- Heat exchangers
- Architectural trim and molding
- Woven or welded screens for mining, quarrying & water filtration
- Automotive and aerospace structural use
- Nuts, bolts, screws, and other fasteners in the marine environment
- Construction material in large buildings
- Dyeing industry
304 Stainless Steel Physical Properties
- Density: 8.03g/cm3
- Electrical resistivity: 72 microhm-cm (20C)
- Specific Heat: 500 J/kg °K (0-100°C)
- Thermal conductivity: 16.3 W/m-k (100°C)
- Modulus of Elasticity (MPa): 193 x 103 in tension
- Melting Range: 2550-2650°F (1399-1454°C)
You can find full details of our 304 stainless steel here.
We supply 304 stainless steel as well as 304L stainless steel in bar, wire, sheet, strip, and billets. Contact us for full details of our service.
