1894.] and Steel and the Effect of Straining and Annealing. 181 



tested, it is found to have returned to a condition almost identical 

 with that which it had at first. In testing again, a new yield point 

 appears, and the new load curve is such a curve as egh. 



Osmond appears first to have suggested that in the case of iron or 

 steel any stress which produces a permanent deformation is attended 

 by a rearrangement of the atoms within the molecules of the metal, 

 such as marks the passage of the iron from one state into another 

 allotropic state.* The following experiments on alternate straining 

 and annealing, in which straining appears always to produce effects 

 like those which occur in hardening steel, and which, like them, are 

 completely destroyed by annealing, would be most easily understood, 

 if Osmond's view were accepted. 



In the following experiments a bar was alternately tested to a 

 stress somewhat beyond the yield point and then annealed. The 

 annealing oven, shown in section in fig. 5, was an iron chamber whh 



FIG. 5. 



* ' Etudes Metallurgiqiies,' Paris, 1888. Also, ' Introduction to the Study of 

 Metallurgy,' by W. C. Koberts-Austen, p. 13. 



