304 stainless is the reference austenitic grade for general corrosion resistance, clean appearance, and reliable formability. In sheet form, it bends, forms, and welds easily while work hardening during forming. In annealed condition it is non-magnetic (slight magnetism may appear after cold deformation).
It resists rust in most indoor environments and many outdoor settings, particularly in washing and food service areas. Surfaces come in 2B (up to 3/16") or #1 (1/4" to 1/2") and accept passivation or electropolishing. Ideal for panels and enclosures, food/pharmaceutical equipment, architectural hardware, guards, tanks, flanges, and durable, easy-to-clean components.
Composition and Properties
Cr-Ni austenitic alloy (≈18% Cr, 8% Ni) balancing corrosion, formability, and weldability; surface hardness superior to aluminum for sharp edges with appropriate tooling.
Corrosion Behavior
Performs well in atmospheric, fresh water, and mild chemical environments; tolerates regular washing in food service.
In chloride-rich environments (coastal spray, de-icing brines, bleach), risk of pitting/crevice corrosion increases; 316 is generally preferred for severe exposures.
After fabrication, passivation restores/thickens the protective oxide.
Forming and Mechanics
Good bending and moderate stamping; work hardens rapidly—plan for appropriate radii and progressive forming for deep shapes.
Springback higher than carbon steel—account for this in bend developments.
Magnetism: Non-magnetic when annealed; may become slightly magnetic after rolling/bending.
Welding and Assembly
MIG/TIG/resistance welding common. Heat-affected zones may be slightly less corrosion resistant; 304L is often chosen to limit sensitization during heavy welding.
Galling possible between stainless threaded surfaces—use compatible anti-seize and reasonable speeds; consider dissimilar or coated hardware.
Isolate from carbon steels to avoid contamination/contact rust.
Surfaces and Finishes
Standard finishes: 2B (rolled) up to 3/16" and #1 beyond (1/4" to 1/2"). Passivation to improve resistance; electropolishing enhances cleanliness and luster.
For uniform appearance on an assembly, group parts from the same batch/finish.
Thicknesses and Typical Uses
0.025"–0.060" (≈0.6–1.5 mm): Panels, light cladding, appliance covers, architectural facings.
0.063"–0.125" (≈1.6–3.2 mm): Enclosures, flanges, machine guards, sink components, food equipment.
0.188"–0.312" (≈4.8–8.0 mm): Structural plates, heavy flanges, tank heads/ends, wear surfaces.
0.375"–0.500" (≈9.5–12.7 mm): Bases, frames, clamping plates, and high-rigidity assemblies.
Cutting and Machining
Fiber laser, waterjet, or machining with sharp edges and thermal management; when drilling/tapping, use lubricant, moderate speeds, and positive feeds to limit work hardening.
Typical 2D cutting tolerance: ±0.005"; small tabs may hold parts for optimal precision.
Common Applications
Food and beverage equipment, architectural hardware and facings, handrails, chemical/pharmaceutical equipment, machine panels and guards, tanks and lids, flanges, supports, and components requiring cleanliness and everyday rust resistance.
In Brief
304 combines attractive appearance, good corrosion resistance, and broad fabrication versatility across a wide thickness range—a reliable choice for industrial and architectural parts meant to last.