18 / 8 stainless steel: Iron + 18% chromium + 8% nickel, which can resist chemical oxidation. This stainless steel is No. 304 in JIS code, so it is also called 304 stainless steel. Stainless steel is an alloy composed of iron, chromium, carbon and many different elements. Iron is the main component element and chromium is the main alloy element.
Generally speaking, the chromium content must account for at least 10.5% to be called stainless steel, because if the chromium content is insufficient, the stainless steel surface will not be able to form a dense chromium oxide protective film and lose the anti-corrosion function. If chromium content is enough, it is not easy to rust in normal temperature atmosphere. There are more than 180 kinds of standard stainless steel visible on the market, but the so-called stainless steel usually refers to 300 series stainless steel (especially 304 series stainless steel).
The characteristic of this kind of stainless steel is non-magnetic, and its metallographic structure and processing properties cannot be changed by heat treatment. However, due to the increase of the population using induction cooker, other metals will be added to this kind of stainless steel to have magnetic conduction effect. And because it contains the alloy element nickel, the corrosion resistance is better than that of stainless steel containing only chromium but no nickel.