191;;] on Recent Advances in Scientific Steel IVletallurgyl 607 



perhaps 100° C, thus enabling engineers to take bigger cuts and 

 work at higher speeds. Later, about 1880, Mushet still further 

 t'ortiiied his liardeuite by the addition of relatively small percentages 

 of chromium, and between 1880 and 1900 self- or air-hardening steels 

 were produced by many steel manufacturers in consideral)le variety. 

 The slide on the screen (Table I.) shows roughly the ranges of 

 chemical composition of turning-tool steels from 1740 to 1912. 



In connexion with cutting steels, a profound sensation was made 

 throughout the steel world when, at the Paris Exhibition in 1900, the 

 Bethlehem Steel Company, of America, showed turning tools made 

 under the alleged patent of Messrs. Taylor and White, cutting very 

 mild steel at a speed which rendered the nose of the tool red-hot. It 

 was obvious that in these tools the thermal stability of the hardenite 

 had been raised to perhaps 600° C. The chemical compositions in 

 the patent embodied nothing which had not been included in the 

 Mushet type of steel for a period of about 20 years prior to the date 

 ui the American patent. In fact what Taylor and White had really 

 done was to show that this type of steel was capable of retaining its 

 cutting edge at a much higher temperature than most engineers and 

 metallurgists had realized. For this demonstration every credit is 

 due to the Bethlehem Company. Sheffield steel-makers, realizing 

 future possibilities, made from the year 1900 and onward a series of 

 experimental researches, which eventually gave to engineers that 

 astonishing material known as High Speed Steel, in which the thermal 

 stability of the fortified hardenite was raised to about 700° C. The 

 slide on the screen (Tal)le I.) shows the striking difference in chemical 

 composition between Mushet's and high speed steels ; nevertheless, 

 the latter are merely a progressive experimental development of the 

 Vol. XX. (No. 107) 2 s 



