Alloy 304 (UNS S30400, 1.4301) is one of the most common grades of stainless steel, thanks to its relatively low alloy content and cost compared with other corrosion-resistant alloys. Its other main elements are manganese, silicon and carbon, with the remainder of the composition primarily iron.
Where 304 is used
It is widely used across domestic and industrial applications, including:
- Saucepans
- Springs, screws, nuts and bolts
- Sinks and splashbacks
- Architectural panelling
- Tubing
- Brewery, food, dairy and pharmaceutical production equipment
- Sanitary ware and troughs
Where a part can be made without welding, it is sometimes substituted with lower cost ferritic stainless steels. Because 304 is easy to source in many product forms, easy to fabricate and easy to weld, other common uses include food processing equipment, automotive trim, fasteners, springs, heat exchangers and industrial equipment.
304 stainless steel properties
Alloy 304 offers excellent corrosion resistance in challenging environments and in contact with corrosive media. Pitting and crevice corrosion can occur in chloride-containing environments, and stress corrosion cracking occurs above 60°C.
It also offers good resistance to oxidation in intermittent service up to 870°C and in continuous service to 925°C, although continuous use between 425°C and 860°C is not recommended.
Alloy 304 readily work hardens. Cold-working fabrication requires an intermediate annealing stage to reduce work hardening and avoid cracking and tearing. Once fabrication is complete, a full annealing operation reduces internal stresses and optimises corrosion resistance. Fusion welding performance is excellent, with and without fillers.
| Alloy 304 property | Value |
|---|---|
| Stress corrosion cracking risk | above 60°C |
| Continuous service oxidation limit | 925°C |
| Intermittent service oxidation limit | 870°C |
| Continuous use not recommended | 425-860°C |