STRENGTH OF STKKL. 



and if the quantity is still further increased beyond this 

 a diminution of strength results. It will be seen from the 

 following figures that with a percentage of manganese of 

 about 14 the steel possesses self-hardening properties, 

 hardening when simply heated and allowed to cool in air. 

 Cooling in oil and water still further hardens the metal. 



In a tensile test of manganese steel it is noticed that 

 there is no very well-marked yield point ; but the most 

 remarkable feature is the almost entire absence of local 

 contraction, the bar elongating over the whole length 

 uniformly up to the point of fracture, indicating great 

 uniformity in the molecular structure of the material. 



The following figures, taken from Mr. Hadfield's^f 

 paper on "Manganese Steel," give some indication of the 

 influence of manganese in various proportions on the 

 strength of the 



In table I. are given results of tests of specimens of 

 manganese steel having different percentages of manganese 

 present. Tables II. and III. comprise results of tests of 

 Hadfield's ordinary steel. JThese latter are quoted for 

 comparative purposes. 



60 



40 



20 



5 10 15 



Percentage of Manganese. 



20 



25 



Fin. ifeC. SHOWING THE EFFECT OF MANGANESE UPON THE ULTIMUK 

 STRENGTH OF STEEL. 



The diagram on Fig. 180 shows graphically the effects 

 on the strength properties of the steel of varying 

 percentages of manganese. 



* "Manganese Steel," Min. Proc. I.C.E., vol. xciii. 



