Manganese in Steel

Manganese in steel improves its hot working properties and increases strength, toughness and hardenability. Most steels contain up to 1% manganese.

The amount of manganese in steel can be determined by oxidising it to permanganate ion (MnO₄^-) and comparing the intensity of the purple colour with the colour of known permanganate solutions.

The method involves dissolving a sample of steel in nitric acid followed by the addition of phosphoric acid and potassium periodate (KIO₄) which oxidises Mn²⁺ to MnO₄^-.

There are numerous published methods, for example see this link.

The graph below shows a calibration curve for potassium permanganate.