How did the Stainless Steel born?
We have so far spoken extensively about stainless steel, its main property ? the passivation ? about the different methods to make a proper and effective pickling, how and why passivate the stainless.
Many curious people (rightly!) write to me asking: ‘How did the Stainless Steel born??
As often it happens in history, even the discovery – or rather invention – of stainless steel came from studies in the field of war.
At the beginning of ‘900, an English chemist named Harry Brearley was working in Sheffield at the Brown Firth research laboratories, trying to find a new steel alloy that could withstand erosion caused by high temperatures in the gun barrels.
It was already known that adding a little of chromium to the steel alloy increased the melting point and the study of the Dr. Brearley aimed at accurately establishing the relationship between the melting points and the chromium content of various steel samples. To do this and to study the microstructure it was necessary to carry out a polishing and etching of the various samples of steel alloy: the standard method to perform this process was a treatment in mild solution of nitric acid and alcohol.
Dr. Brearley realized that not only some samples were resistant to attack in nitric acid, but even if left at open air, after several days their appearance was still brilliant and would not show even a point of oxidation. Dr. Brearley didn?t know, but he created the first stainless steel and with the nitric acid solution he even well-passivated it!
After several researches, it was determined that the samples with these characteristics showed a high chromium content (at least 10.5% as already seen, to ensure proper passivation). Starting from this research, around the area of ??Sheffield a new industry arose, and it was specifically dedicated to the production and study of stainless steels.
Still today, the stainless steel is also applied in the industry of firearms.