Harry Brearley (1871-1948) is usually credited with the invention of "rustless steel" (later to be called "stainless steel"), although Krupp filed a patent for its brand of Nirosta a few months before Brearley's breakthrough.
1871 February 18th. Brearley was born in Sheffield the son of a steel melter.
He left school at the age of twelve to enter employment as a labourer in Thomas Firth and Sons steelworks, being transferred soon afterwards to the post of general assistant in the company's chemical laboratory.
For several years, in addition to his laboratory work, he studied at home and later in evening classes, to specialize in steel production techniques and associated chemical analysis methods.
By his early thirties, Brearley had earned a reputation as an experienced professional and for being very astute in the resolution of practical, industrial metallurgical problems.
1901 he left Firths to start a new laboratory at another Sheffield steelworks, Kayser, Ellison and Co. While there, he wrote the first of his technical texts (with Fred Ibbotson), The Analysis of Steel-works Materials (1902).
1903 Brearley returned to Firths, after its acquisition by John Brown and Co. He became chief chemist at Firth's Salamander works at Riga
1907 Brearley became the first director of a newly created research division — the Brown-Firth Research Laboratories, jointly financed by the 2 companies.
1912 While researching steel for small arms use (to reduce erosion of gun barrels), Brearley tried low carbon steels containing about 12 % chromium. Brearley found that the new chromium steels were very resistant to chemical attack (used to etch the surfaces for study) - in fact such steels resisted corrosion. He saw their commercial possibilities and alerted Firths but they showed little interest. He suggested using the steel for cutlery and made tests to establish the materials' potential.
Brearley initially called the new alloy "rustless steel"; the term "stainless steel" was later suggested by Ernest Stuart of R. F. Mosley, a local cutlery manufacturer. It is reported that the first true stainless steel, a 0.24wt% C, 12.8wt% Cr ferrous alloy, was produced by Brearley in an electric furnace on August 13, 1913.
1914 the Sheffield cutlery firm of George Ibberson and Co succeeded in making knife blades from the new alloy
WWI Production of stainless steel was well established. Virtually all research projects into the further development of stainless steels were interrupted by the War, but efforts were renewed in the 1920s.
1915 Harry Brearley left the Brown Firth Laboratories, following disagreements regarding patent rights, but the research continued under his successor, Dr. W. H. Hatfield, who is credited with the development, in 1924, of a stainless steel which even today is probably the widest-used alloy of this type, the so-called "18/8", which includes nickel (Ni) in its composition (18wt% Cr, 8wt% Ni).
Brearley became works manager of Brown, Bayleys Steel Works in Sheffield, a company he was to be associated with until his death.
1920 Brearley was awarded the Iron and Steel Institute's Bessemer Gold Medal.
Stainless steel was never patented in Britain but Firths and Brearley protected the rights in the USA, Canada, Italy, France, and Japan, so that any Sheffield firm intending to export to these countries needed a licence from the Firth-Brearley Stainless Steel Syndicate — an organization founded in 1917, which made good profits for Firths and Brearley in the 1920s.
1848 August 12th. Died in Torquay. He is buried at Sheffield Cathedral.
1948 Obituary 
Mr. Harry Brearley, Technical Director of Brown, Bayley's Steel Works Ltd., died on 14 July 1948 at his home in Torquay at the age of 77.
He was born in February 1871, and received his schooling at Woodside Board School, but began work at the age of 12 with Thomas Firth and Sons Ltd., as a cellar lad. Subsequently he entered the laboratory under James Taylor, to whom Mr. Brearley frequently paid tribute for his help and encouragement.
Returning to Firth's in 1903, he was offered, in 1904, the appointment of chief chemist at their Salamander Works, Riga, and in 1905 was appointed works manager there. While at the Salamander Works he became interested in the production of pyrometers, and in that connection was responsible for the formation of Amalgams Company Ltd., which produces the pyrometer bearing his name.
At the end of 1907 he returned to Sheffield to design and equip the proposed joint research laboratories for Thos. Firth and Sons Ltd. and John Brown and Co. Ltd. While studying the causes of erosion and fouling in rifle barrels in 1912, experiments were carried out by Mr, Brearley which eventually led to the discovery of the stainless properties of high-chromium steels. As a result of further investigations with these high-chromium steels, the first stainless knives were made for Mr. Brearley in June 1914, by Mr. E. Stuart, of R. F. Mosley and Co. Ltd.
Early in 1915 Mr. Brearley left the Brown—Firth research laboratories to become works manager of Brown, Bayley's Steel Works Ltd., the firm with which he was associated until the time of his death. Later he was appointed technical director of the Company. He was also a director of the Firth—Brearley Stainless Steel Syndicate, Chairman of Amalgams Company Ltd. and of Welding Rods Ltd., and a director of the Brearley Ingot Co. Ltd.
He was the author of several technical books, notably "The Case-Hardening of Steel", "The Heat-Treatment of Tool Steel", "Ingots and Ingot Moulds ", and "Files and Filing". In 1933 he wrote "Steel-Makers", and in 1946 the American Society for Metals published in America a volume entitled "Talks About Steelmaking", which was originally a series of articles contributed to The British Steelmaker.
He contributed many other articles to the technical press, and in 1941 he wrote "Knotted String: Autobiography of a Steel-Maker", which was closely followed by further reminiscences under the title "Earning a Living".
In 1920 he was awarded the Bessemer Gold Medal of the Iron and Steel Institute, and in 1939 he was made a Freeman of the City of Sheffield. He became a member of the Institute of Metals in 1919. There was a very strong humanitarian side to Mr. Brearley's personality. His interest in his fellow-men, their hopes and aspirations, found expression in the formation of the Freshgate Trust Foundation. It was formed, as he himself put it, "to help lame dogs over stiles", or, in other words, to make life more livable for those whose occupations obliged them and their families to live in unlovely industrial areas.
Mr. Brearley is survived by his wife, their only son having died two years ago.
1948 Obituary 
Discovery of Stainless Steel
"The so called "stainless steel" was first introduced in 1914 in the form of table cutlery, and its a almost exclusive use for cutlery purposes for some time after that date has led to the belief that "stainless steel " is simply a special type of cutlery steel with a very limited range of mechanical properties. In reality, however stainless steel is really "a whole series of steels whose mechanical and physical properties vary widely in a manner similar to the variation met with in the different varieties or tempers of ordinary carbon steels, all of which have the distinguishing property of great resistance to corrosion conferred upon them primarily by the presence of a suitable percentage of chromium." As a general rule, the amount of this element present from 11 to 14 percent.
The original discovery was made by Harry Brearley in 1913, at that time chief of the research laboratory maintained by John Brown and Co, and Thomas Firth and Co of Sheffield. The story is told of Mr Monypenny in the following words:-
"He (Brearley) was at the time engaged on an extensive research on the resistance to erosion of various steels in reference to their use for rifle and naval guns. Among the steels examined for this purpose were some containing large amounts of chromium. In the course of these investigations numbers of samples in different conditions of heat treatment were examined microscopically, as is, of course, usual in such investigations. In carrying out this examination Mr. Brearley noticed that these high chromium steels were either not etched at all or only attacked very slowly by the usual reagents used for etching the polished surfaces of sections of steels prepared for microscopic examination, and that, moreover, they had not rusted when exposed for considerable periods to the atmosphere of the physical laboratory. He also found that, both with the usual microscopical reagent and also with new types developed for the purpose, the same steel, under different conditions of heat treatment, would sometimes etch and sometimes not. He was at once struck with these marked characteristics, and proceeded to investigate both the limiting ranges of composition for producing a steel practically resistant to ordinary corrosion and also the conditions of heat treatment necessary with any particular steel for developing to the greatest extent his resistance to corrosion."