When first discussing the differences between 304 stainless steel and 316 steel we must first understand what stainless steel is. Stainless steel is always made using chromium. The minimum amount of chromium used to make stainless steel is 10.5%; it is chromium that makes the steel stainless. Chromium also improves the corrosion resistance by forming a chromium oxide film on the steel. This very thin layer, when placed under the right conditions, can also be self-repairing.
Other elements used to make stainless steel as well, including nickel, nitrogen and molybdenum. Bringing these elements together forms different crystal structures that enable a variety of properties in machining, welding and forming.
There are four major types of stainless steel. The first and most widely used is austenitic It has a nickel content of at least 7%, which makes it very flexible. It is used in a range of houseware products, industrial piping and vessels, constructional structures and architectural facades.
Ferritic stainless steel has similar properties to mild steel, but better corrosion resistance. This type of steel is commonly used in washing machines, boilers and indoor architecture. Martensitic stainless steel is a very hard, strong steel. It contains around 13% chromium and is used to make knives and turbine blades.