88 Barrett, Brown & HapvrieLp—On the Electrical Conductivity and 
Group 10.——-NickeL-Curomium STEELS. 
Marks. | Percentage Composition. Conductivity Copper = 100. BP Gaeeay nee 
Ni | Cr | C Unann. | Ann. Unann. Ann. 
1286 A 2°75 0°75 0°25 6:9 | TD 24°9 23°9 
1480 2°00 2°00 0:90 6°7 6:8 25°6 25°38 
1286 C 2°50 1:75 0:31 459 6:2 30°1 27-7 
1327 C 3°25 1°75 0:86 4:2 6:0 40°9 28°5 
1210 D 2°50 4°50 0:41 4:0 4:9 43°0 35°] 
*1450 12°24 2°01 0-64 ol 3°3 55°2 62:1 
The effect of chromium on the conductivity of these steels is well seen by 
comparing 1286 A and C, very similar alloys, except that the latter has 1 per 
cent. more chromium init: an addition that increases the resistance 3°8 microhms. 
Compare also 1286 C and 1210 D, which mainly differ in the latter containing 2°75 
per cent. more chromium—a difference that increases the resistance 2°6 microhms 
for each 1 per cent. of added chromium; the resistance increasing at a slower rate 
as the alloy becomes richer in chromium (cf. Group 7). The last specimen, 1450, 
has nearly 10 per cent. more nickel than the one preceding it, 1210 D, and also 
higher carbon and manganese, hence its conductivity is lower, notwithstanding the 
reduction of 25 per cent. in the chromium. A much greater effect is produced on 
the conductivity by silicon added to a nickel steel, as follows: 
Group 11.—NicKrL-Srinicon STEELS. 
Marks. Percentage Composition. Conductivity Copper = 100. | ae 
Ni Si C Annealed. Annealed. 
71447 A 12°70 0°39 0°81 4:0 43°0 
{1447B | 12:10 0-56 0:97 3°8 45:0 
1103 A | 3°25 2°00 0°38 39 44:0 
1102 A | 1:00 2°00 0:79 3°4 50°5 
1031 C Nn RS x50 325 022 3:0 57:4 
As was the case with the nickel chromium steels in Group 10, the large quantity 
of nickel present im the first two specimens above, 1447 A and B, has a less effect 
* This specimen also contained 0°54 per cent. of manganese. 
+ These two specimens also contained 0°61 per cent. of manganese. 
