558 G. H. Mathewson — Metallographic Description 



top. When placed in the vise and strained, the first effects 

 were felt in the lower part of the specimen, while, later, the 

 metal near the top came under the influence of the load. 

 Sufficient pressure was applied to cause permanent deformation 

 of the order shown by the changed dimensions of the aperture 

 in fig. 32. At the lower part of the specimen, deformation has 

 been sufficiently intense to plainly ruffle the surface. Above 

 the aperture, the degree of deformation decreases to a very 

 small value at the top. Upon annealing this specimen, we 

 should, therefore, obtain the characteristics of recrystallization 

 after heavy and light deformation, respectively, upon different 

 portions of the surface. The structure after an anneal of 15 

 minutes at 775°, is shown in fig. 33. Here, we observe a fine- 

 grained, but rather uniform structure, in the lower left-hand 

 corner of the specimen where deformation was most severe. 

 This structure corresponds to the ordinary effect obtained in 

 annealing metal which has been cold-worked to a point of con- 

 siderable reduction in area of section. It may be characterized 

 by application of the usual counting methods (cf. figs. 2, 3, 

 4, with discussion). In other parts of the ' specimen, only 

 partial refining of the grain has occurred. Near the top, frag- 

 ments of the original grains may be identified. The small 

 light grain, to which early reference was made, may still be 

 seen in the upper right-hand corner. Below this, a little to 

 the right, a sharp-edged fragment of a large white grain, which 

 reaches to the top in preceding figures, can be distinguished. 

 As already stated,* it is difficult to characterize recrystallization 

 of this sort (after light deformation), since the recrystallized 

 grains cannot be distinguished from the residual fragments. 

 As related to an original cast structure, the fact of recrystalliza- 

 tion is clearly apparent, but, as related to a structure which 

 itself shows twins and the general characteristics of recrystal- 

 lization, even the fact of a subsequent recrystallization is likely 

 to remain obscure. In every case, the grain size and general 

 appearance is highly dependent upon the previous structure. 

 A partially refined grain of this character may be seen in fig. 

 60. This represents a spot near the broad end of a chisel 

 belonging to the present collection. Large fragments of the 

 casting grains have remained after working and subsequent 

 annealing. The alteration of shape at this point must have 

 been slight and the temperature of anneal high enough to 

 remove cores, viz., bright red heat unless the period was 

 considerably prolonged. 



* See p. 554. 



