What should be added to pure iron to make stainless steel?
Chromium and nickel are added to a pure iron to make stainless steel.
Chromium
Chromium is a highly reactive element and accounts for the “passive” nature of all stainless steels. The resistance to the chemical effects of corrosion and the typical “rusting” (oxidation)that occurs with unprotected carbon steel, is the direct result of the presence of chromium. The higher the chromium level the greater the protection.
Nickel
Nickel is the essential allying element in the stainless steel. The role of nickel has no direct influence on the development of the “passive” surface layer, it results in significant improvement in resistance to acid attack, particularly with sulfuric acid.