History Of Stainless Steel
Only a few corrosion resistant iron has achieved to survive from ancient times up to today. The most famous and largest example of this is the "Iron Pillar of Delhi", which was built by Kumara Gupta I in Delhi, India in the 400's. But unlike stainless steel, the non-corrosive function of this iron monument does not come from chromium, but it comes from it's being rich in phosphorus.
Phosphorus, together with suitable regional weather conditions, forms a protective surface layer consisting of iron-oxide and phosphorus on the surface of the monument and provides resistance to the iron against corrosion.
The corrosion resistance of iron-chromium alloys was first recognized by French metallurgist Pierre Berthier in 1821.
The technology at that time was not enough to process the iron and chromium as it is today, so they could not achieve to use it in practice. In the 1890s, the German Hans Goldschmidt discovered the aluminothermic method leading to the production of carbon-free chromium. Since that time, many studies have been conducted in the field of stainless steel.
The beginning of modern stainless steels began in 1913 by the British metallurgist, Harry Brearly. Coincidentally, he discovered the stainless steel when he was making research to develop rifle barrels. Then, it became the starting point of stainless steel. In later studies, austenitic stainless steel (304), which was described as 18-8, came onto the market in the 1920s and a huge success was achieved through its practice.
Since the 1930s, stainless steel has been irreplaceable in the industry and in our daily lives. Researchers, who continued these developments with other alloying elements, developed different kinds of stainless steel qualities that we know today. About 70 years ago, duplex stainless steels have been developed to be used in the sulfide paper industry. At the first stage, duplex alloys were used to cope with the corrosion problem caused by chlorite bed cooling water and other sharp chemical process fluids.
In the 1970s, a second generation of duplex stainless steel was developed with the development of gas and oil stations in the North Sea. Accordingly, a certain amount of nitrogen addition increased the toughness, weldability, chlorite corrosion resistance. The most commonly used mixed composition called UNS S31803 was standardized in 1996 in the duplex steel UNS S32205.
