Stainless Steel Foils

A human hair measures about 0.05 mm across. The thinnest stainless steel foils leave the rolling mill at one fifth of that — and still carry the corrosion resistance, strength and temperature tolerance of full-thickness plate. That combination of extreme thinness and full alloy performance is why foil keeps showing up wherever engineers run out of space but not out of demands.

Eata Energy supplies stainless steel foils across the industrial and research spectrum: austenitic 304/304L, 316/316L, 301 and 321, heat-resistant 310S, and ferritic 430 — in thicknesses from 0.01 mm to 0.2 mm, tempers from dead-soft annealed to super-elastic full hard, and finishes from matte 2D to bright-annealed mirror. Coils are slit to width, cut to length, or blanked to your drawing.

Master coils of cold-rolled stainless steel foil awaiting precision slitting.

What Exactly Is a Stainless Steel Foil?

The industry draws clean lines by thickness: below 0.2 mm you have foil, between 0.2 and 2 mm it is strip, and above 2 mm it becomes sheet. Within the foil range, the 0.01–0.1 mm band is classed as ultra-thin — territory that only repeated cold rolling on multi-roll precision mills (Sendzimir-type 20-high stands) can reach, with intermediate annealing at 950–1,100 °C between passes to restore ductility. Automated gauge control holds thickness within a tolerance band of just ±1–2 microns.

Chemically, nothing separates a foil from its parent plate — 304 foil still carries 18–20% chromium and 8–10% nickel and grows the same self-repairing passive film. What changes everything is temper. Cold work accumulates with every rolling pass, so the same grade can leave the mill dead soft and formable, or harder than many structural steels, depending on how the customer intends to use it.

Why Foil Gauge Changes Everything

• Strength is a choice, not a fixed value. Annealed 304 foil sits near 515 MPa tensile with 40% elongation; in full-hard temper the same chemistry exceeds 1,275 MPa. One alloy, a whole spectrum of mechanical behavior.
• Formability or springiness — pick one per part. Dead-soft foil deep-draws into complex shapes; extra-hard 301B at 480–580 HV and above snaps back like spring steel for clips, diaphragms and flexible couplings.
• Corrosion resistance survives the thinning. The passive chromium-oxide film forms identically at 0.01 mm as at 10 mm, so foil performs in chemical, marine and process environments without special provision.
• Heat tolerance depends on grade, not gauge. Standard 304 serves continuously to about 870 °C; 310S pushes past 1,100 °C in air, making foil wrap and furnace fixtures viable.
• Magnetic when you need it. Annealed austenitic foils are essentially non-magnetic, while ferritic 430 foil stays magnetic — useful for shielding and sensing designs.
• Precision is the product. At foil gauges, ±1–2 μm thickness tolerance and controlled flatness are not marketing extras; they are what make stamping, laminating and winding processes repeatable.

Grades We Stock

Ultra-thin stainless foil — flexible enough to curl, strong enough to hold a spring temper.

Tempers, Finishes and Supply Forms

• Tempers to standard conventions — annealed (≤200 HV), quarter and half hard (200–340 HV), three-quarter and full hard (340–480 HV), plus extra-hard and super-hard 301B beyond 480 HV for the most demanding spring work.
• Surface finishes — 2B general-purpose bright, BA bright-annealed for electronics and clean applications, 2D matte, HL hairline, and mirror finishes on 304 and 316L.
• Supply forms — master coils, slit coils down to a few millimeters wide, cut-to-length sheets, and blanked discs or shapes; edge condition is controlled for stamping and winding operations.
• Standards coverage — material is produced and certified to ASTM A240/A666, EN 10088-2, JIS G4305 or GB/T 4239 as your project file requires.

Precision slitting turns master coils into the narrow widths that stamping and winding lines need.

Where These Foils Earn Their Keep

Precision Shims, Gaskets and Seals

Alignment, spacing and sealing all depend on material that holds its dimension under bolt load and thermal cycling. Full-hard stainless foil stamps cleanly into shim washers, gasket rings and seal elements that stay put — and resist the media they seal against.

Shim washers and gasket rings stamped from full-hard stainless foil.

Springs, Diaphragms and Bellows

Pressure-sensing diaphragms, instrument springs, flexible couplings and disc springs live or die by elastic memory. Extra-hard 301-series foil delivers that memory in a corrosion-proof package, which is why it dominates this application space.

Corrugated diaphragms and disc springs rely on high-temper 301 foil for elastic memory.

Energy and Electrochemical Devices

Battery and fuel-cell laboratories reach for thin stainless foil constantly: as substrate and carrier material, as cell hardware and spacer stock, as blanks for bipolar-plate development, and as corrosion-stable partitions in electrolysis and flow-battery experiments. For energy research, foil gauge and edge quality often decide whether a prototype cell behaves or leaks.

In battery and fuel-cell labs, stainless foil serves as substrate, spacer and cell hardware material.

EMI Shielding and Electronics

Shielding cans, connector springs, cable wrap and enclosure gaskets exploit the same trio of properties: conductivity, formability and corrosion-proof surfaces that keep contact resistance low for years.

Heat Treatment and High-Temperature Work

Toolmakers wrap parts in 321 or 310S foil packets before hardening to shield surfaces from oxidation and decarburization; furnace builders use the same grades for fixtures, liners and exhaust components that cycle past 1,000 °C.

Research and Prototyping

Universities and corporate labs order mixed-grade, mixed-temper trial packs — a few meters each of 304, 316L and 301 in several gauges — to screen materials before committing a design. We treat these small, varied orders as first-class work, not as exceptions.

Why Order Foil from Eata Energy

• Tolerance you can measure. Thickness is verified by micrometer and certified per lot — the ±1–2 μm control that foil work demands is documented, not implied.
• Temper verified, not assumed. Vickers hardness is checked and reported with every shipment, so your spring design or drawing die sees the temper you specified.
• Edges built for production. Precision-slit, burr-controlled edges protect stamping dies and winding equipment alike.
• Quantities matched to the program. A ten-meter laboratory roll or full coil quantities — both are routine orders for us.
• Grade guidance without the upsell. 304 versus 316L, half-hard versus full hard: describe the part and its environment, and we will help you choose — including when the less expensive option is the right one.

Custom Foil Services

Non-standard thickness windows, coils slit to unusual widths, sheets cut to size, discs and blanks to drawing, special tempers between standard conventions, finishes beyond the standard menu, and mixed-grade trial packs for material screening — if your design needs it, ask. Send us the grade, gauge, temper and quantity you have in mind, and Eata Energy will reply with a technical proposal and a quotation.

For Research or Industrial Raw Materials, Not For Personal Medical Use!