4 8 



NATURE 



[March 13, 1913 



of the hardenite was raised to a tempera- 

 ture of perhaps 400° C, thus enabling 

 engineers to take bigger cuts and work at higher 



^3 



C^5 



*1I 



U I) 'J 



1800 



Hardening Temperature in 

 Degrees Fahrenheit 



Fig. 4.— Physical diagram claimed by Messrs. Taylor and White for tungsten 



speeds. Later, about 1880, Mushet still further forti- 

 fied his hardenite by the addition of relatively small 

 percentages of chromium, and between 1880 and 1900 

 self- or air- 

 hardening 

 steels were pro- 

 duced by many 

 steel manufac- 

 turers in con- 

 S i d e r a b 1 e 

 variety. 



In connec- 

 tion with cut- 

 ting steels, a 

 profound sensa- 

 tion was made 

 throughout the 

 steel world 

 when , at the 

 Paris Exhibi- 

 tion in 1900, 

 the Bethlehem 

 Steel Co. of 

 America 

 showed turn- 

 ing tools made 

 under the 

 alleged patent 

 of Messrs. 

 Taylor and 

 White, cutting 

 very mild steel 

 at a speed 

 which ren- 

 dered 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 6oo° 



C. The chemical compositions 

 embodied nothing which had not 



twenty years prior to the date of the American patent 

 In fact, what Taylor and White had really done was 

 to show that this type of steel was capable of retaining 

 _B its cutting edge at a much higher tempera- 

 ture than most engineers and metallurgists 

 had realised. For this demonstration every 

 credit is due to the Bethlehem Company. 



Sheffield steel-makers, realising future 

 possibilities, made from the year 1900 and 

 onwards a series of experimental researches 

 which eventually gave to engineers that 

 astounding material known as high-speed 

 steel, in which the thermal stability of the 

 fortified hardenite was raised to about 700° 

 C, and the striking difference in chemical 

 composition between Mushet's and high- 

 speed steels was shown ; nevertheless, the 

 latter are merely a progressive experimental 

 development of the former. 



The claims of the Taylor-White patent 



were the subject of a protracted lawsuit, the 



costs of which were about 50,000^. In the 



end, Mr. Justice Cross, of the United States 



Circuit Court, in a lengthy and luminous 



judgment, pronounced the Taylor-White 



ome steels patent to be absolutely invalid. Nevertheless, 



it is still claimed that the patent in suit was 



utilised by British manufacturers in producing modern 



high-speed steel. It is, therefore, only fair to consider 



what this patent really claimed. 



1900 2000 



O2UU0 



28000 



24000 



20000 



16000 



12000 



8000 



4000 



1500 1600 1700 



1800 1900 2000 2100 



Quenching Temperatures 



Degrees Fahrenheit 



5.— Physical curves obtained by Arnold and McWilliam for tungsten-chr 



2200 2300 2400 



1 the patent 

 been included 

 in the Mushet type of steel for a period of about 

 xi '. 2263, VOL - 9 1 ] 



Fig. 4 shows a physical curve 

 chrome steels which the patentees 



of tungsten- 

 claimed to 



have discovered. The coordinates are vertically the 



