1902.] 



produced by the sudden Cool Ing of Metals. 



Diagram No. 3 .shows the effect produced on the elastic properties of 

 Lowraoor iron by quenching from TOO 3 C. Curve A was obtained 

 from an annealed specimen of the material. A very clearly defined 

 yield-point is shown at the stress of 33,000 lbs. per square inch. After 

 the yielding at the yield-point had spread throughout the specimen, 

 the load was steadily increased until fracture occurred at the stress of 

 50,300 lbs. per square inch. The extension produced was 0"'95 on 

 4 inches, neglecting all the local extension which occurred at the point 

 of fracture, or l"-23 including the local extension. 



Curve B, which was obtained from a specimen which had been 

 quenched from 700° C, clearly shows the loss of elasticity produced 

 by quenching. A curious recovery effect was noticed- in this test. 

 The load was applied until a stress of 30,000 lbs. was attained, and 



Diagram No. 3.— (Lownioor Iron.) 



jpoo Lbs/in 2 . 



35 1 



^30 



I 



I 

 •^1 



15 







A. 











B. 







t 



d' 12 i.e. 



about, 





^ 



4 



feett 



iscaU 

























t 





1 





A 



7 



























t 

















i 















6 



oado) 

 bouth 



rforl 

 Hour] 







Extensions diminished 'bu io^oo t - s of &n inch for every /qooo pounds) 



of stress) 



Sc6Lte:-lUnit=^o^ of &n inch , 2 . 



Diameter of specimens A and B 

 Length under test = 4 //, 00. 



CT-44. 



Specimen A. — Annealed at 750° C. Broke at 50,300 lbs. per square inch. 



Extension 0"*95 omitting, or 1"'23 including, local extension. 

 Specimen B. — Heated to 740° C, slowly cooled to 700° C, and then quenched in 

 cold water. Broke at 61,300 lbs. per square inch. 



Extension 0"'61 omitting, or 0' /- 88 including, local extension. 



