This day in tech 1913- Stainless Steel

Making the Delorean and hence time travel possible.

This monument to stainless steel pioneer Harry Brearley stands at the former Brown Firth Research Laboratories, where he formulated the alloy in 1913.
Courtesy David Morris/Geograph project collection.

1913: English metallurgist Harry Brearley casts a steel alloy that's resistant to acidity and weathering. Because his sponsor names it "stainless steel," Brearley will often be credited as the inventor, but there are more metallurgists than metals in this story.

Even the hometown British Stainless Steel Association acknowledges that Brearley was not alone.

English and French researchers had learned as early as the 1820s that iron-chromium alloys resisted some acids. But they were restricted to low- rather than high-chromium-content alloys, because they hadn't yet figured out the necessity of lowering the carbon content.

Two Englishmen filed a patent for an acid-resistant steel with 30 to 35 percent chromium and 2 percent tungsten in 1872. But it was a French researcher named Brustlein who in 1875 detailed the importance of low carbon content. He determined that a high-chromium alloy would need carbon content below 0.15 percent or thereabouts.

The race was on. Very slowly. Many attempts produced many failures over the next 20 years.

Hans Goldschmidt of Germany broke the logjam in 1895 with the development of the aluminothermic reduction process for producing carbon-free chromium. French metallurgist Leon Guillet forged ahead, so to speak, with work on iron-nickel-chromium alloys in the first decade of the 20th century, but seemingly ignored their resistance to corrosion. Back in Germany, P. Monnartz and W. Borchers discovered in 1911 that having a minimum 10.5 percent chromium seriously increased steel's resistance to corrosion.

Enter Harry Brearley of Sheffield, England. He started working on a project in 1912 for a small-arms manufacturer that wanted to prevent its rifle barrels from eroding away quickly from the heat and friction of gunshot. Brearley needed to etch his steel-alloy samples to examine their granular structure under the microscope, but when he used nitric acid, the high-chromium samples resisted being dissolved. His focus shifted from erosion resistance to corrosion resistance.

After trying various combinations with 6 to 15 percent chromium and differing measures of carbon, he made a new alloy on Aug. 13, 1913, containing 12.8 percent chromium and 0.24 percent carbon. It resisted not only nitric acid, but lemon juice and vinegar as well.

So he took his discovery of "rustless steel" to Sheffield cutler R.F Mosley. A manager there, Ernest Stuart, renamed it "stainless steel."

But wait, there's more. Metallurgists at Germany's Krupp Iron Works were also working on high-chromium, corrosion-resistant steel alloys of various compositions between 1908 and 1914. Elwood Haynes and two other Americans were doing parallel work in the years 1908-1911, and Max Mauermann of Poland displayed something similar at the 1913 Adria exhibition in Vienna. And there's a Swedish claimant as well.

Brearley, however, did formulate the first alloy to be called stainless steel, and he recognized potential uses others had not seen. Today is the 95th anniversary of his discovery.