Which material is characterized by having more than 15% chromium and excellent corrosion resistance?

Stainless steel is defined by its high chromium content, typically more than 15%, which is a critical alloying element that significantly enhances its resistance to corrosion and oxidation. This property is vital for applications where exposure to moisture or corrosive environments is common, making stainless steel an ideal choice in various industries, including food processing, medical devices, and marine applications.

The presence of chromium forms a thin, passive layer of chromium oxide on the surface of the steel, which protects the underlying metal from further corrosion. The unique balance of chromium and other alloying elements in stainless steel contributes to its strength and durability, while also allowing for the potential of various finishings and aesthetic qualities.

Other materials mentioned do not possess these characteristics to the same degree. Tool steel and carbon steel generally have lower chromium content, resulting in reduced corrosion resistance while providing different mechanical properties suited for tooling applications. Alloy steel, while it can have various alloying elements, also typically lacks the high chromium content needed for the exceptional corrosion resistance that distinguishes stainless steel. Thus, stainless steel stands out in this context due to its specific alloy composition and its functional characteristics.