Tri-Ply Circles
SS304 vs SS430 in Tri-Ply Circles: Grades Explained
Two stainless grades in one circle, each doing a different job. Understand them and you can spec circles like a metallurgist - and catch substitutions.
SS304 - the food side
18/8 chromium-nickel steel. Excellent corrosion resistance, non-reactive with food, easy to polish to a hygienic finish. Used on the inner layer (and sometimes the outer for non-induction lines). The nickel content is what you are paying for.
SS430 - the flame side
Ferritic, magnetic steel. Less corrosion-resistant than 304, but magnetic - which makes the vessel induction-compatible. Used on the outer layer. Cheaper than 304; perfectly adequate where it never touches food.
The aluminium core
Usually 1050/3003 series. The heat-spreader: aluminium conducts heat ~15x better than steel, killing hotspots. Core proportion (often 40-60% of thickness) sets heating performance.
Substitutions to watch for
- 201 instead of 304: cheaper, less corrosion-resistant - the classic downgrade
- Thinner aluminium core: same total gauge, worse heating
- Non-magnetic outer: kills induction compatibility silently
Verify: magnet test (outer must attract), mill test certificates per lot, and periodic third-party PMI (positive material identification).
Frequently asked questions
Why is the outer layer SS430?
SS430 is magnetic, making triply cookware induction-compatible. SS304 is non-magnetic and would not work on induction hobs.
How do I verify steel grades?
Mill test certificates per lot, a magnet check on the outer layer, and periodic third-party PMI testing for high-value orders.
Have a cookware project in mind?
We manufacture triply cookware and supply tri-ply circles for OEM, private label and distribution. Tell us your specs - we reply with a quote.