Period 4 element in period 4, between chromium and iron. Manganese is often found free in nature, but is also found in combination with iron. Manganese, like chromium before it, is an important component in stainless steel, preventing the iron from rusting. Manganese is also often used in pigments, again like chromium. Manganese is also poisonous; if enough is inhaled, it can cause irreversible neurological damage. Iron (Fe) is an element in period 4, between manganese and cobalt. Iron is probably the most well-known element in period 4, being the most common element in the earth and a major component of steel. Iron-56
Stainless steel there are other materials that are corrosion-resistant but not stainless steel. There are over 150 grades of stainless steel, of which 15 are most commonly used. There are a number of systems for grading stainless and other steels, including US SAE steel grades. Standard mill finishes can be applied to flat rolled stainless steel directly by the rollers and by mechanical abrasives. Steel is first rolled to size and thickness and then annealed to change the properties of the final material. Any oxidation that forms on the surface (mill scale) is removed by pickling, and a passivation layer is created