The common materials compared
| Material | What it is | Corrosion resistance | Typical use |
|---|---|---|---|
| SS304 | Austenitic stainless with roughly 18% chromium and 8% nickel | High; handles moisture, food acids and salt well | Interiors, worktops, exteriors in wet or coastal sites |
| SS430 | Ferritic stainless with chromium but essentially no nickel | Moderate; fine in dry indoor use, more prone to rust with salt and acids | Exterior panels and doors in dry, indoor locations |
| 200-series (e.g. 201/202) | Austenitic stainless where manganese partly replaces nickel | Lower than 304; can stain or rust in humid or salty conditions | Lower-cost panels and fabrication |
| GI (galvanised iron) | Mild steel with a zinc coating | Good until the coating is scratched or cut, then rusts | Hidden structural parts, backs and bases |
| Powder-coated or pre-painted steel | Mild or galvanised steel with a baked paint finish | Good while the coating is intact; chips expose steel | Exteriors of visi coolers and display units |
Why 304 resists corrosion better
Stainless steel resists rust because chromium forms a thin, self-healing oxide film on the surface. Nickel stabilises the austenitic structure and improves resistance to acids and chlorides. That is why 304 tolerates salt water, tamarind, vinegar, lemon juice and many cleaning chemicals better than 430, which has a similar chromium content but no nickel.
No grade is immune. Bleach and strong chlorine cleaners, salt left drying on the surface and steel wool scrubbing can all break the protective film, even on 304.
Where the grade matters most
- Interiors, where brine, marinades, meat juices and condensation sit on the surface.
- Worktops on undercounter and prep units, which see acidic food and daily cleaning.
- Coastal cities such as Mumbai, Chennai, Kochi and Visakhapatnam, where salt-laden air attacks steel even indoors.
- Seafood, pickle and meat processing areas with heavy salt and acid exposure.
- Kitchens that clean with strong chemicals or high-pressure water.
Mixed builds are normal; hidden ones are the problem
It is common and reasonable for a cabinet to use 304 inside, 430 or coated steel on the outside, and galvanised steel for hidden backs and bases. Each choice balances cost and durability. The problem arises when a quote just says 'stainless steel body' and you discover later that the interior or worktop is a lower grade.
Ask suppliers to state the grade separately for the interior, exterior, doors, worktop and base, and to put it in the quotation.
How to check what you are buying
The magnet test is often suggested, but it is only half a test. Ferritic grades like 430 are magnetic, so a strong magnet sticking firmly suggests a ferritic grade. But 200-series stainless is also austenitic and non-magnetic, just like 304, so a magnet cannot tell 304 from 202. Formed or welded 304 can also be slightly magnetic in places.
For larger orders, ask for material test certificates from the steel supplier, or have a sample checked with a handheld analyser at a testing lab. A supplier confident in their material will not object.
Caring for stainless in Indian kitchens
- Wipe with mild detergent and warm water, then dry; avoid leaving salt or acid on the surface overnight.
- Use soft cloths or non-scratch pads and wipe along the grain of the brushed finish.
- Avoid bleach and chlorine-based cleaners on stainless; if used, rinse thoroughly.
- Remove tea-coloured staining early with a cleaner made for stainless steel before it develops into pitting.
- Touch up chipped powder coat promptly so the steel underneath does not rust.
Frequently asked questions
- Is SS430 good enough for a commercial refrigerator?
- For exterior panels in a dry, indoor, air-conditioned space it often performs well. For interiors, worktops, wet kitchens and coastal sites, 304 is the safer choice.
- Can a magnet tell me if steel is SS304?
- Not reliably. A magnet can flag a ferritic grade such as 430, but it cannot distinguish 304 from 200-series grades, which are also non-magnetic. Ask for material certificates.
