STAINLESS STEEL

Stainless steel—a term derived from the French word acier inoxydable—is technically defined as any steel alloy composed essentially of iron (Fe) and carbon (C), incorporating a minimum chromium (Cr) content of 10.5% by mass. This proportion of chromium is sufficient to form a passive layer of chromium oxide (Cr₂O₃) on the surface of the material, giving it remarkable resistance to atmospheric and chemical corrosion, even in aggressive environments.

However, in industrial and commercial practice, the term "stainless steel" is applied with some flexibility. It is common to refer to any ferrous alloy that exhibits significant resistance to oxidation, even if it does not strictly meet the aforementioned chromium threshold. This broad use can lead to ambiguity, especially when comparing metallurgical compositions or evaluating specific properties in regulatory contexts. Therefore, in this space, the standard definition based on the iron-chromium alloy will be adopted as the main reference, reserving for later a detailed analysis of the variants and exceptions that arise in contemporary metallurgical practice.