Magnetic Permeability of various Alloys of Iron. LIL? 
The effect on magnetic hardness produced by different percentages of various 
metals added to iron is shown in fig. 12, where the ordinates represent coercive 
force and the abscissee percentages of the added element. The steady rise in the 
case of the tungsten steels is noticeable. The wonderful softness produced by the 
addition of silicon to steel is not shown in fig. 12, but will be referred to presently. 
Ct ae ee 
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ee el 
45 
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Coercive force. 
nN 
Per-contage aw added element 
Ihe, 1. 
The addition of chromium to aluminium steel has the effect of hardening it, 
and, therefore, injuring the valuable magnetic properties of a pure aluminium 
steel. Aluminium and chromium have, therefore, opposite effects on steel 
magnetically. 
Taste XII.—Chromium Aluminium Steels (Plate VIII.). 
Marks. Percentage. Max. induction. | Retentiyity. | Coercive force. | « forH=8. Paiean ht 
Cr Al 
Iron) | — — 17480 7120 166 | 1560 11090 
1178 D | 1:5 2°25 | 14460 8990 3°52 | 11380 | 18090 
, | 15 | 4:50 | 18705 Coa) || ee | | RY 
els 1:75 0°75 15070 9690 6:00 | 964 26550 
1179 B | 3°50 1:00 14400 9500 8:00 | 363 35780 
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