|In 1901, he left Firth's to start a new laboratory at Kayser Ellisons steel works but in 1903, he returned to Firth's and then spent three years in Russia, becoming works manager of Firth's steel plant in Riga.
In 1907 he returned to Sheffield to take charge of the Brown - Firth Research Laboratory.
In 1912, he was investigating corrosion (rusting) of rifle barrels. As a result of his investigations, he developed a chrome alloy steel which was much more rust resistant than the steel which had been used until then.
Brearley resigned from the Firth company in 1915 after arguments about the ownership of the rights to the invention of stainless steel. The company claimed that they owned the rights as Brearley was an employee of the firm. Brearley claimed that he should be entitled to at least half of the ownership.
Harry became works manager at Brown Bayley's Steel Works in Sheffield, where he continued with the development and production of stainless steel. He was awarded the Iron and Steel Institute's Bessemer Gold Medal in 1920. He eventually became a director of Brown Bayley in 1925.
Brearley's chrome steel formed the basis for the wide range of stainless and special steels which are now used so widely.
Harry Brearley died on the 14th July 1948, in Torquay.