Wiki-Special steel

Steel is an alloy of iron and carbon that contains more than a certain amount of elements other than Fe (iron) and C (carbon). Stainless steel is one of these steels, and is called as such if its Cr (chromium) content is more than 10,5% and C content is less than 1,2%.

Related websites
Stainless Steel in Japanese Knives: Rust Resistance & Sharpness | KIREAJI