304 Stainless Steel: Complete Guide to Properties, Composition & Uses

304 is the default stainless for kitchen sinks and equipment, food and beverage processing tanks, architectural trim and handrails, mild-chemical storage vessels, heat exchangers, medical instruments, fasteners, and automotive trim. Specify it whenever no particular corrosion requirement calls for a higher alloy like 316.

Annealed 304 is essentially non-magnetic. Cold working (forming, drawing, machining) transforms some austenite to martensite, causing cold-worked areas (bent corners, drawn corners, machined surfaces) to become slightly magnetic. This is normal and does not affect corrosion resistance. For strictly non-magnetic applications, consider 316L or a high-nickel alloy.

304 resists rust in atmospheric, freshwater, and mild chemical environments. However, it can develop cosmetic 'tea staining' (surface rust) in coastal areas or when exposed to chlorides (salt spray, pool water, de-icing salts). For coastal or chloride service, specify 316/316L instead. 304 can also pit in stagnant seawater or strong chloride solutions—never use it for seawater immersion.

Yes, 304 has excellent weldability by all standard processes (TIG, MIG, SMAW, resistance). Use ER308L filler metal for matching chemistry. For welded components that will see corrosive service, specify 304L (low carbon) to prevent intergranular corrosion (sensitization) in the heat-affected zone. Standard 304 is acceptable for welded components in mild environments or when post-weld solution annealing is performed.

316 adds 2-3% molybdenum, dramatically improving resistance to chloride pitting and crevice corrosion. Choose 304 for indoor, freshwater, food, and mild chemical service. Choose 316/316L for marine, coastal, pharmaceutical, or any chloride-containing environment. 316 costs roughly 25-40% more than 304, so avoid specifying it unnecessarily.