Magnetic Permeability oj various Alloys of Iron. 



115 



Table IX.— (Plate V.) 



The specimen, 1430 A, has nearly 9 per cent, of chromium added to a steel 

 containing 3 per cent, manganese, and also very high carbon. Upon referring 

 to Tables IV. and V., it will be seen that a corresponding steel without the 

 chromium has higher coercive force but lower retentivity, and on comparing the 

 respective areas of the curves given in Plates III. and V., the larger hysteresis 

 loss in the manganese chromium steel is apparent. This comparison is of the 

 annealed specimens ; the effect of annealing is seen to be much greater on the 

 chromium-manganese steel, which is but feebly magnetic in the unannealed state 

 in this field. The large hysteresis loss, shown by 1420 in the unannealed condition, 

 is due to its high coercive force combined with great induction and retentivity ; 

 the large area of this curve is seen on Plate V. On referring to Group 2, jd. 76, 

 it will be noticed that this steel has 0-75 of carbon and 1 per cent, of manganese, 

 whereas 4147 has the same percentage of manganese and only 0'24 carbon. 

 This small difference in the carbon will be seen to make a great difference in the 

 hysteresis loss of the annealed specimens in the two cases (see Tables V., p. 109, 

 and IX. above) ; in the unannealed state probably a still greater difference would 

 be found ; the specimen 4147, however, was not tested before being annealed. 



The next Table gives the magnetic properties of all the tungsten steels we 

 have examined. 



Table X.— Tungsten Steels. (Plate VI.) 



TKANS. ROY. DUli. see, N.S. VOL. VII., PAST IT. 



