1902.] 



produced by the sudden Cooling of Metals. 



81 



fully described in a paper by the present author " On the Recovery of 

 Iron from Overstrain."* The amount by which the curves have been 

 sheared back is marked at the foot of each diagram. Thus, in 

 Diagram No. 1, TF V°7?oo tns of an inch have been deducted from the 

 extension of the 4-inch length for every 4 tons of stress. For 

 example, the extensometer readings for stresses of 4, 8, and 12 tons 

 per square inch were 120, 240, and 360 respectively; the numbers 

 actually plotted were 20, 40, and 60. The origin for the measurement 

 of extensions has been displaced for the various curves of each diagram 

 in order to avoid a confusion of the curves. 



Diagram No. 1 shows the elastic properties of an annealed specimen 

 of mild steel. The specimen was subjected to a series of tension tests, 

 the load in each test being carried just to a yield-point. Recovery 

 from the overstrains produced by the passing of the successive yield- 

 points was effected by heating the specimen to temperatures of from 



Diageam No. 1. — (Mild steel-annealed.) 



tons/in 2 . 



50 



\ 



b 

 1 



^3 



10 













Fr&ct 



ure. 







3 A 



/m 



3) 







/ fo'-'o 



ej 









fo'-'o 



o) 



(About 



■2'6"}- 



,// 





fo'-'o 



8/ 





w 









omitb 





//l 



Hi 









/ 





Extensions diminished by-, 



>j s of&n inoh forev@ry4tons ~) 

 2 of stress } 



Sc&le:-/Unik=^ w *. h of&n inch, f / 



Diameter of specimen = 0"*331. 

 Length under test = 4 //- 00. 

 Fracture occurred at 40 tons per square inch original area. Extension (including 

 all yield-points) - 0"'38 on 4 inches. 



200° to 250° C. The specimen broke at the fifth yield-point, the 

 breaking stress being 42 tons per square inch, or about 40 tons per 

 square inch taking the original area of the specimen. After the pass- 

 ing of each yield-point the diameter of the specimen was of course 



* ' Phil. Trans.,' A, vol. 193, 1899. 



