1904.] Liquid Air Temperatures on Iron and its Allot/*. 333 



(C 1-18, Mn 6-05, Ni 24-30 per cent.) shows a still further increase in 

 percentage of nickel. For the first time in this series of tests there is 

 now met with a specimen in which there is an actual rise in ductility 

 at -182 C. The tenacity now rises from 5184 tons, and the 

 ductility from 60 to 67 per cent. This is remarkable. It is curious 

 that the considerable percentage of manganese does not interfere with 

 the toughening of the iron, of which there is 68 per cent. In any case 

 it cannot be claimed that manganese confers this, as it must be remem- 

 bered that a similar percentage of manganese in an iron alloy containing 

 no nickel shows remarkable brittleness either at normal or low tem- 

 perature. Nor does an iron alloy containing a similar high percentage 

 of nickel and no manganese show much ductility. In face of these 

 apparent anomalies it is difficult to offer a satisfactory explanation of 

 the remarkable effects noticed. A repetition of the above test showed 

 even more remarkable results, the ductility rising from 42 57 

 per cent. 



The liquid air experiments on this series (iron, nickel, manganese) 

 bring out in a much clearer manner than any other tests have yet done, 

 the remarkable toughness and ductility of the iron alloys containing 

 6 per cent. Mn and 14 24 per cent, nickel. They show what an 

 extraordinary molecular combination has been produced. In other 

 words, these particular iron alloys have almost non-magnetic properties, 

 possess the highest electrical resistance of any known alloy, and also 

 represent the most ductile iron alloy yet known. 



The Concluding Group includes Metals and Miscellaneous Alloys. The 

 first specimen taken in this group was No. 120 forged nickel (C 0*09, 

 Ni 99 '27 per cent.), representing an excellent quality of commercial 

 nickel. This was tested in the forged condition, and in liquid air the 

 tenacity was increased from 29 46 tons, and ductility from 43 

 51 per cent. This may be considered a remarkable result, and 

 probably explains why in iron-nickel and iron-nickel-manganese alloys 

 the presence of nickel (provided the carbon is low) prevents low 

 temperature injuring iron. It is difficult to explain why this should 

 be so, in view of the similar position of these two elements in the 

 chemical classification of the elements. 



Although no absolutely pure specimen of the metal manganese is yet 

 available, that containing about 98 per cent, shows comparative brittle- 

 ness, and in this respect, therefore, entirely differs from the metal nickel. 

 This, to some extent, explains why nickel-iron alloys are remarkably 

 tough, but still leaves unsolved why manganese steel, which contains 

 1 2 per cent, of Mn, is so extraordinarily tough when alloyed with iron 

 and some carbon, and quenched from high temperatures. 



Test No. 131 (copper 99 per cent.) shows that whilst the results 

 obtained from this metal resemble nickel, the tenacity being increased, 

 it is to a much less degree, the ductility not being materially altered. 



2 C 2 



