SS 430 ferritic stainless: nickel-free and magnetic

Nickel. 304 carries 8–10.5% nickel, and nickel is one of the most expensive and price-volatile alloying elements in stainless steel. 430 has none beyond a 0.75% residual limit. Its corrosion resistance comes from chromium alone, at 16–18%.

Without nickel, the steel does not form austenite. It stays ferritic, with a body-centred crystal structure like ordinary carbon steel. That is why a magnet sticks to it firmly, and why it behaves differently in forming and welding. The price difference against 304 changes with the nickel market, but 430 is consistently the cheaper of the two.

Indoors, in kitchens, in dry or mildly humid air and in contact with most foods and mild detergents, 430 stays bright with ordinary cleaning. It also handles nitric acid well, which is why it was historically used in nitric acid plant equipment.

It is less forgiving than 304 in wet, salty or acidic service. Near the sea, in bathrooms with chlorinated cleaners, or outdoors where dirt and moisture sit on the surface, 430 can develop surface rust, staining and pitting faster. It also tends to stain in crevices. For exterior work or anything that stays wet, choose SS 304 or 316 instead.

430 forms well in moderate operations such as bending, light drawing and roll forming. It work-hardens less than 304, which helps on press lines. Very deep draws are harder than with 304, because ferritic steel has lower ductility.

Welding is where you need care. The heat of welding causes grain growth in the heat-affected zone, which reduces toughness and ductility, and 430 cannot be refined back by heat treatment. Thin-gauge appliance work welds acceptably. Heavy sections and load-bearing welds are not what 430 is for. Stabilised ferritic grades exist for better weldability, but for structural welded work, an austenitic grade is the usual answer.

430 resists scaling in air to about 870 °C intermittently and about 815 °C in continuous service. Long exposure around 400–500 °C can cause 475 °C embrittlement, a loss of toughness at room temperature, so avoid holding it in that range.

Choose 430 when the part lives indoors or in mild conditions, does not carry heavy welded loads, and benefits from being magnetic or lower in cost. Typical uses include appliance panels and liners, cooker hoods, sink and counter trim, automotive trim, decorative interior panels, fasteners for mild service, and induction-compatible cookware bases, where the magnetic response is needed for the hob to work.

In industry, 430 appears in heat-exchanger parts and furnace components that stay below its scaling limit, and in some solenoid and magnetic applications.

• Indoor, dry or mildly humid environments: good fit
• Food contact and kitchens: good fit with regular cleaning
• Coastal, outdoor or constantly wet service: use 304 or 316
• Heavy welded structures: use an austenitic grade

In the Indian market, buyers sometimes worry that a magnetic sheet means they have been sent the wrong material. With 430 the magnet sticks by design. The real check is the certificate. 430 should show chromium of 16–18% and nickel under 0.75%. 304 shows nickel of 8% or more, and 200-series grades show high manganese with reduced nickel.

If you have ordered 304 and a magnet sticks firmly to flat, unworked sheet, ask for the test certificate before fabricating. If you have ordered 430, a magnet test that sticks is simply confirmation.

430 is mainly supplied as cold-rolled sheet and strip in 2B, BA and brushed finishes, plus round bar and wire. Perforated and shim sheet are also available. Sizes are confirmed at enquiry. Every lot comes with a test certificate, and the low nickel figure on that certificate is your quick confirmation that you have 430 rather than a 200-series or 300-series grade. Browse our sheets, strips and sections for flat products.