Overstrain  and  Recovery  of  Aluminium,  etc. 
l0    inch   and   reduced   its 
pecimen  was  then  tested 
beino; 
gave    it    a    permanent    strain    of 
diameter  to   1*109  inches.      The 
after  intervals  of  20  minutes,  1  hour,  and  5  days  ; 
heated  for  3  minutes  to  99°  C.  before  the  first  two  tests  after 
the  overstrain.  The  results  are  shown  in  Table  XIII.,  from 
which  the  broken-line  curves  in  fig.  9  have  been  plotted  in 
the  order  A,  B.  C,  D.  Examination  will  show  that  recovery 
is  complete  after  the  first  heat  treatment,  the  material  showing 
slio-htlv  more  hardness  than  before  overstrain. 
Table  XIII. — Specimen  No.  2  (Aluminium-Bronze). 
2nd  Loading. 
3rd  Loading. 
1st  Loading. 
Oct.  19,  1905. 
After  3  rats,  at 
99°  C.  and 
After  3  more  mts. 
at  99°  O,  and 
4th  Loading. 
5  days  after 
Time 
Load 
20  mts.  after 
1  hour  after 
overstrain. 
in 
in 
overstrain. 
overstrain. 
Minutes. 
Tons. 
1 
Reading. 
Diff. 
Reading. 
Diff. 
Reading. 
Diff. 
Reading.!   Diff. 
0 
0 
200 
200 
200 
200     !     ... 
1 
1 
260 
60 
262 
62 
262 
62 
262         62 
2 
2 
325 
65 
327 
65 
328 
66 
325 
63 
3 
3 
389 
64 
390 
63 
392 
64 
388 
63 
4 
4 
453 
64 
455 
65 
456 
64 
453 
65 
5 
5 
520 
67 
519 
64 
522 
66 
518 
65 
6 
6 
587 
67 
586 
67 
588 
66 
585 
67 
7 
7 
655 
68 
654 
68 
653 
65 
652 
67 
8 
8 
724 
69 
721 
67 
722 
69 
719 
67 
9 
9 
794 
70 
789 
68 
790 
68 
787 
68 
10 
10 
865 
71 
859 
70 
861 
71 
857 
70 
11 
11 
938 
73 
12 
12 
1011 
73 
13 
13 
1087 
76 
16 
37 
I 
1 
Specimen  No.  2  was  then  again  overstrained,  by  a  load  of 
38  tons,  giving  a  further  permanent  extension  of  T\,  inch, 
and  was  retested  at  the  same  intervals  as  before,  but  without 
heating,  with  the  results  given  in  Table  XIY,  The  full  line 
curves  in  the  order  A,  B,  C,  D,  fig.  9,  have  been  plotted  from 
Table  XIV.  in  consecutive  order.  They  show  that  with  lapse 
of  time  the  aluminium-bronze  recovers  its  original  properties 
much  more  slowly  at  ordinary  atmospheric  temperatures  than 
at  99°  C.  The  "  shearing  back,"  in  figs.  9  and  10,  is  at  the 
rate  of  5*5  extensometer  divisions,  i.  e.  0*0011  inch,  per  ton  of 
load. 
Finally,  the  effect  of  vibration  on  overstrained  aluminium- 
bronze  was  investigated.     From  results  of  tests  made  on  a  trial 
