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Tempered Will

Stainless steel celebrates a century of rustless existence

Tempered Will
AFP (From Outlook 12 August 2013)
Tempered Will

Stainless steel—that long-enduring, lustrous material which we reflexively think of as a marker of ‘modern’ life, much like neon lights, Disney cartoons and zip fasteners—is one hundred years old. Well, saying it like that immediately raises two possible points of contention. One relates to the “rustless wonders” made of that old Indian alloy, panchaloha, which has a minor headstart of some two millennia. The other is less grandiose, a quibble about dates. By now, it’s well accepted that stainless steel was invented in August 1913 by Harry Brearley, a self-taught metallurgist and analytical chemist. He made the first commercial cast of stainless steel on August 20, 1913, at Tho­mas Firth and Sons. Cast No. 1008, as it was known, had a composition of 12.8% chrom­ium, 0.24% carbon, 0.44% manganese and 0.20% silicon. Like many other inventions, it was a happy accident. And yes, society was slow to grasp its utility.

Harry Brearley was born in 1871 in Sheffield into a penurious family of a steel plant worker. To supplement the family income, he started doing odd jobs at age 11. A determined lad, he progressed rapidly from being a laboratory bottle-washer to become works manager at the steel factory of Firth and Sons. In 1908, Firth and Sons joined hands with John Brown, another steel manufacturer, to create Brown Firth Research Laboratories, where Brearley was appointed as the research director. Those were the days leading up to World War I and there was a flourishing trade in arms and ammunitions. A particularly pernicious problem plaguing gun manufacturers was the excessive erosion of the rifling of gun barrels. Brearley started researching on steel that could resist erosion better at high temperatures. His efforts were focused on studying the effect of varying concentrations of chromium and carbon.

The various experimental compositions had to be scrutin­ised for their microstructure, for which it had to be etc­hed with a dilute nitric acid solution. Brearley found that samples with high chromium content were not so easily etc­hed. He describes the discovery in his autobiography: “When microscopic studies of this steel were being made, one of the first noticeable things was that the usual reagent used for etching the polished surface of a microsection would not etch or etched slowly. The significance of this is that etching is a form of corrosion....” It was a Eureka moment for Brearley.

The tradition of cutlery manufacture in Sheffield dates back to the 16th century. Knives and other items made of carbon steel were prone to rusting and had to be frequently polished. Brearley tested his high-chromium steel on vinegar and lime juice. The result was astonishing; he promptly christened it “rustless steel”. Starting out with the aim of finding a more wear-resistant steel, Brearley had unwittingly stumbled upon a more corrosion-resistant material. But the invention got a cold reception. One of the bosses at Firth pompously declared, “Rustlessness is not so great a virtue in cutlery, which of necessity must be cleaned after every use.”

Brearley turned to R.F. Mosley, a local cutler, to manufacture kitchen knives with his newfound alloy. The first kni­ves tur­ned brittle, but Brearley got it right by fine-tuning the harden­ing temperature. Ernest Stuart, the manager at Mosley, dec­l­ared that “this steel sta­ins less” and thus was coined ‘Stainless Steel’. Brearley’s farsightedness over its utility was evident when he wrote in 1914: “These materials would appear specially suited for the manufa­cture of spindles for gas or water met­ers, pistons and plungers for pumps, ventilators and valves in gas engines.”

In 1915, Brearley quit Brown Firth after repeatedly being denied consent to apply for a patent. It was John Maddox who coa­xed Brearley to apply for a patent in the US. He did so on March 6, 1916, and was gran­ted one by September. Oddly, the patent was for cutlery. His application reads, “My invent­ion rel­ates to new and useful improvements in cutlery or other hardened and polished articles of manufacture where non-staining properties are desired and has for its object to provide a tempered steel cutlery blade or other hardened article having a polished surface and composed of an alloy which is practically untarnishable when hardened or hardened and tempered.” In celebrating Brearley’s achie­vement, it would be unfair to ignore other pioneers. Like Germans Eduard Maurer and Benno Strauss, who in 1912 created an alloy of 23% chromium and 9% nickel, similar to the most widely used stainless steel of today and also Ame­rican Elw­ood Haynes, who got into a patent litigation with Brearley, claiming his discovery was similar. The two later agree to a cordial commercial cooperation.

(The author is head of engineering, Uhde India, Pune.)

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