HARDENED BY OVERSTRAIN. 
19 
yield-point is raised after recovery from overstrain has been slightly diminished. 
Recovery from the various overstrains was effected hy heating to about 150^ 0. 
The series of curves marked B in Diagram 5 shows by comparison with the first 
series of curves in the diagram the influence of time on the effect of annealing. The 
specimens from which the two series of curves were obtained had both been heated 
Diagram No. 5. (Annealed Lowmoor Iron.) 
Extensions—diminished as explained on page 
Scale ;—i Unit — of an inrh f ^ _j 
A—Lowmoor Iron annealed for a few minutes at 770’ C. and allowed to cool in air. 
B— „ ,, ,, 6 hours at 750° C. and cooled very slowly. 
to about the same temperature, but specimen A was simply raised to that 
temperature (770° C.) and then allowed to cool slowly in the air, while specimen B 
was kept at the temperature (about 750° C.. and never higher than 780° C.) for six 
D 2 
