The discovery of stainless steel in 1912

In 1912 Friedrich Krupp AG filed a patent for a steel grade with high corrosion resistance. The chromium-nickel alloy needs a special heat treatment to develop its corrosion resistance, however it is cheap to produce and easy to machine.

Flanges and dome covers

In 1960 the trademark “Edelstahl rostfrei” was registered in Germany. Until then however, production of stainless steel was very low at around 2.2 million tons per year. Only after the discovery of new applications in the sixties, for example in household appliances, production started to rise. In 2011 the production of stainless steel reached 32 million tons.

Today the most important applications of stainless steel are in the production of medical instruments and household appliances. The Chrysler building provides a good example of the high durability of stainless steel. The roofing shingles did not have to be replaced since 1930. At the Burj Khalifa in Dubai stainless steel was used for parts of the façade.

The underlying principles of stainless

Stainless steel contains chromium which reacts with oxygen in the air to form a protective chromium oxide layer on the surface. This effect is called passivation and can also be observed in aluminium and magnesium.

To achieve passivation, the proportion of chromium in the alloy must be above 10.5%. A high amount of chromium leads to bad machining properties and high hardness. Nickel is added to reduce these unwanted effects.

Tube plate

Machining and processing can be difficult

Machining of stainless steel is similar to machining of standard construction steel. It is important however, to prevent contact with other less noble metals. When stainless steel comes into contact with iron oxide, the passivation can be inhibited, leading to corrosion of stainless steel.

Originally the width of stainless steel coils was limited due to the high deformation energy needed to roll wide sheets. With the introduction 20-high sendzimir mill clusters it became possible to roll sheets with widths above 1500mm.

INTERSTAHL offers many services for stainless steel. We can deliver many grades from stock and also offer machining.