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Stainless Steel or (Just) Steel?

Stainless steel, as a whole, is "rust-resistant" (although not "rust-proof"). Different grades provide different degrees of rust-resistance. Nevertheless, the following 2 statements holds true:

  1. A higher "grade number" for stainless steel does not necessarily mean better rust-resistance.
  2. Galvanised steel and mild steel are not stainless steel

In this article, we will discuss the commonly-seen and used stainless steel grades in a commercial kitchen equipment environment as well as the reason they are priced differently.

A substantial portion of the cost of any metal is made up of the price of each individual element that is used in the composition. Importantly, Nickel and Chromium are 2 main elements that contribute to rust-resistance (as well as costs).

The following table indicates the commonly-found percentages of these important elements in each of the stainless steel grades:

  Stainless Steel
  430 (Economic) 201
(Basic)

304
(Standard)

Nickel Composition
(important ingredient in rust-resistance)

0% 3.5% - 5.5% 8% - 10.5%
Chromium Composition
(contributes to rust-resistance)
16% - 18% 16% - 18% 17.5% - 19.5%
Rust-Resistance
(eg. How effective is the rust-resistance?)
Average Good Excellent
Durability of Rust-Resistance
(eg. For how long will the rust-resistance last?)
Average Good Excellent

 

Stainless Steel Grade: 304

  • Is generally more expensive than 210 or 430
  • Contains between 8% and 10.5% nickel
  • More rust-resistant than both 201 and 430

Stainless Steel Grade: 201

  • Is generally cheaper than 304
  • Contains between 3.5% and 5.5% nickel
  • More rust-resistant than 430 (but less than 304)

Stainless Steel Grade: 430

  • Contains 0% of Nickel, a critical element in rust-resistance
  • Depending on usage style, less durable than both 201 and 304
  • Typically polished, which provides a glossy look

 Galvanised Steel (NOT Stainless Steel)

  • Regular steel coated in a layer of zinc (hot-dipping / electro-dipping)
  • Significantly weaker than stainless steel
  • Does not provide protection against rusting for as long a period as stainless steel

Mild Steel (NOT Stainless Steel)

  • Mild steel does not have a chromium oxide protective layer (unlike stainless steel)
  • The iron present in mild steel reacts with the moisture in the air to produce iron oxide or ‘rust’
  • Requires further processing such as galvanising in order to give it a protective surface

 Fully Stainless Steel? (Or Fully 304-Grade Stainless Steel?)

There's a difference. Manufacturers, in a bid to remain competitive, sometimes combine different grades of stainless steel in a single product - and simply label them "fully stainless steel" or "made of 304-grade stainless steel". However, not all parts may be of the same grade. eg. The surface of a work table may be 304-grade, but its legs may not be. Always ask and clarify whether the product you are interested in is fully 304-grade stainless steel for ALL of its parts as its rust-resistance may be influenced by the grade used.

Conclusion

In short, different grades of stainless steel are manufactured and designed for different purposes. Depending on your usage style and cost-concerns, you may require a different grade. However, galvanised steel and mild steel are not stainless steel, and should only be considered as alternatives rather than substitutes. At the same time, always ask and clarify if the product you were quoted is made fully of a single grade of stainless steel (or a combination which may affect quality and/or rust-resistance).