82 



Dr. J. Muir. On Changes in Elastic Properties [Aug. 11, 



slightly reduced ; this was allowed for in the succeeding loadings, the 

 load being always applied in tons per square inch of actual section. 



Diagram No. 2 shows the elastic properties of the same steel after it 

 liad been heated to 500°, to 650", and to 700° C, and quenched in 

 water at about 15° C. Each of the specimens employed was broken 

 by a single continuous loading. Curves A and B show that quenching 

 from 500° and from 650° C. had little effect on the elastic properties of 

 the steel. The specimen from which Curve B was obtained had been 

 more thoroughly annealed before quenching than Specimen A. and 

 this may account for the lower breaking load and greater ultimate 

 -extension obtained with Specimen B, although all the specimens 

 •employed were primarily annealed. Curve C shows that a marked 

 change was produced in elastic properties by quenching from 700" C. 



Diagram ]So. 2. — -(Mild steel-quenched.) 



tons/ in 2 

 30i 



20 > 



\1 IG 



A-q 



uenche 



d from 

 500 °C. 



i 



B- cfue> 



nched i 

 6, 



rom\ 

 >o°C.l 





/ Broi 



38 



Exte 

 o'-'t 



<e &t 

 tons/in? 

 'ns/bn - 

 7on4" 



} / 



' Bro 

 36 

 EocL 

 0- 



ke at 

 tons/h 

 'ens ion - 

 &4 on 4'. 



} 

















Extensions diminished (&a below). 



tons/in 2 . 



O0r 





C-cjuet 



>chedf 



rom70 



o ^^ 













roke& 

 xtensk 



brupti 

 m-d'-IC 



on <4 in 



tons/in. 

 ohes. 

















Extensions diminished by -, 



Sea. I e:- I Unite I £ ro t '?ofa.n inch 



fosQf an inch for every 1 

 4 tons of stress) 



Diameter of Specimens A, B, and C = //, 37. 

 Lengths under test = 4 //- 00. 



The material after quenching showed no range of elasticity. Hooke's 

 law was departed from gradually from the lowest loads till ultimately 

 fracture occurred abruptly at the high stress of 52 tons per square 

 inch. The ultimate extension was onlv 0"T0 on 4 inches. 



