Graded Series of Chrome Steels at Low Temperatures. 837 

 Table II. (Fig. 3.) 

 4*08 per- cent. Cr. 



Thermal treatment 



Annealed at 900° C. 



Quenched at 900° C. 







Temperature of test 



15° C. 



-190° C. 



15° C. 



-190° 0. 





H. 



I. 



I. 



I. 



I. 



10 

 20 

 40 

 60 

 100 

 150 



160 

 680 

 892 

 980 

 1078 

 1142 



125 

 608 



878 



970 



1088 



1158 



38 

 95 

 317 

 630 

 840 

 945 



24 

 68 

 270 

 590 

 820 

 935 



namely 70 c.G.s. units. The curve taken at room-tempera- 

 ture after the test at —190° C. is again slightly below I at 

 the beginning of the range and slightly above it at the end,,, 

 but the improvement only sets in when the field is greater 

 than 110 c.Q.S. units. The effect of quenching in reducing 

 the susceptibility of this specimen is more marked than in 

 the case of the previous specimen, but the effects of 

 lowering the temperature after quenching are exactly 

 similar in the two cases, — the curve taken at — 190° C 

 lying everywhere below that taken at room-temperature, 

 and the two curves taken at room-temperature, the one 

 before and the other after immersion in liquid air, exactlv 

 coinciding. 



Specimen III. (8 per cent. Cr.). — The results obtained on 

 submitting this specimen to the various tests (see Table III. 

 and fig. 4) were again somewhat similar, but the saturation. 



Table III. (Fig. 4.) 

 8 per cent. Cr. 





Annealed at 900° C. 



Quenched at 900° C. 







Temperature of test 



15° C. 



-190° C. 



15° C. 



-190° C. 





H. 



1. 



I. 



I. 



I. 



10 



88 



78 



18 



17 



20 



400 



340 



48 



42 



40 



790 



778 



130 



120 



60 



888 



878 



304 



286 



100 



984 



980 



600 



580 



150 



1060 



1070 



744 



724 



Phil. Mag. S. 6. Vol. 27. No. 161. May 1914. 3 K 



