

Mr. .1. Muir. 



! th- Hustle properties of the steel \vlm-r rngffl propeitiai are 



illustrated 1y Diagiam 1. Tin; primary yield-point UM- < on-i<lurably 

 lowered by annealing, ami the step by which the yield-point was raised 

 in consequence of overstrain und recovery from overstrain was con- 

 siderably reduced. 



The material in the condition as supplied yielded (as is illustrated 

 by Diagram 1) at 38 tons per square inch, and after the yield-point 

 had Iteen raised by fir<> steps of 11 tons, fracture occurred at 60 tons 

 per square inch. The same steel, after annealing at 750" C., is shown 



DIAGRAM 2. 

 (Steel annealed at 750' C.) 



Extensions . / Unit 



Curve 1. Primary test. 



2. Shortly after 1. 



3. Ij day's 1. 



4. 2 weeks 1. 



of *n inch tJLJ 



Curve 5. After heating to 300 3 C. 

 > o. ,, ,, ,, 



> ' 



by Diagram 2 to have yielded at 29 tons per square inch, and finally 

 to have fractured at 59i tons per square inch, after the yield-point had 

 l>een raised four times by a step of about 7A tons per square inch. 

 The i-iuch steel rod when in the condition as supplied by the makers 

 was thus shown to 1x5 in a state of hardness possessing certain dis- 

 tinctive properties. 



It was found that the steel in the condition as supplied could be 

 tempered or partially annealed by heating to various temperatures 

 lower than the ordinary annealing temperature of alxmt 750 C. -. 



The following table illustrates this tempering from the condition as 

 supplied, the material being a rod of steel very similar to that referred 



