[ 460 ] 



ON THE MAGNETIC MOMENT AND OTHER PHYSICAL CON- 

 STANTS OF STEEL CONTAINING FROM ONE TO TWENTY- 

 ONE PER CENT. OF MANGANESE. By Professor W. F. 

 BARRETT. 



[Eead November 20, and December 18, 1889.] 



Having lately received from my friend Mr. R. A. Hadfield, of 

 the Hecla Steel Works, Sheffield, various specimens of his now- 

 well-known manganese steel, I submitted the samples to investiga- 

 tion for the purpose of determining the magnetic moment per 

 gramme that could be given to steel containing largely different 

 percentages of manganese. Mr. Bottomley was the first to draw 

 attention to the extremely low susceptibility of manganese steel. 

 In a paper read before the British Association, in 1885, he showed 

 that whilst ordinary steel when magnetised to saturation has a 

 moment, varying according to the steel, from 30 to 90 c. g. s. 

 units per gramme, steel containing 13 per cent, of manganese, 

 when magnetised in a very powerful field, had a moment of only 

 0"013 units per gramme. 



In a previous paper of mine read before this Society, 1 and in a 

 subsequent paper read before the British Association, in 1887, 2 1 gave 

 the results of a series of experiments I had made on the remark- 

 able physical properties of this steel, which Mr. Hadfield had, 

 after much difficulty, succeeded in drawing for me into wire. 

 This was accomplished by heating the alloy to a bright white heat 

 and then suddenly cooling it in cold water : a reverse effect to that 

 produced on ordinary steel results ; instead of becoming brittle 

 and glass-hard, manganese steel so treated loses some of its hard- 

 ness and becomes exceedingly tough, so that it can be drawn or 

 bent cold into any shape. It still, however, remains very difficult 

 to drill or work in the lathe owing to its hardness — in fact, it has 



i Proe. E. D. S., vol. v., 1886, p. 360. 



2 For full report see " Electrician," November, 4, 1887. 



