On the Microstructitre of Hypo-eutectoicl Steel. 271 



tougli and durable in use. I remember one such worthy man to 

 whom I mentioned the crystalline structure of iron and steel. His 

 concluding comment was, " Well, crystals or no crystals, I gives 

 the stuff a good hammering, because, as I says, good stuff always 

 goes in little room ! " If some of that muscular snuth's energy 

 could have been used to put the " stuff in little room " in this case, 

 No. 9 would have presented a much more satisfactory picture. 



The photograph No. 4 (fig. 10) was taken at the top of the 

 specimen, and illustrates how the large crystals shown in No. 9 

 have failed to preserve their original formation under the repeated 

 pressures exerted by the wheels of the rolling-stock. Seeing that 

 immediately below this position the general structures w^ere the 

 same as No. 9, we can safely assume that this was the original 

 condition at No. 4 when this rail was first put into use. If any- 

 thing it is possible the condition was aggravated, seeing that this 

 part must necessarily have been nearer to the surface of the ingot 

 when exposed to the conditions obtained in the heating-furnace. It 

 wdll be noticed that the structure as a whole has broken down, and 

 the original pearlite polyhedrons have been crushed down one upon 

 the other and deformed. 



The seventh photograph (fig. 11) was taken in the sulphur 

 segregation below the test-depression. The pearlite and ferrite are 

 well defined, and careful scrutiny will reveal the enclosures of MnS 

 surrounded by the ferrite in each case, and MnS in turn containing 

 small inclusions of manganese silicates, although not to the same 

 extent as seen previously. 



In the eighth photograph (fig. 12), taken below the test 

 depression in the specimen cut from the foot, we find the pearlite 

 assuming another form quite different from that shown in the 

 previous photographs. Presenting as it does rather an emulsified 

 appearance, it leads one to think that the full development has been 

 arrested before completion. By analysis the carbon-content (which 

 is the principal element necessary for the formation of pearlite) is 

 for all practical purposes the same in this part of the steel as in 

 the other parts already seen, and consequently one expects to find 

 the structure here to be much the same in formation. To this 

 imperfect development the name of " sorbite," or " sorbilic pearlite," 

 has been given. It is apt to result by a rapid cooling of hot- 

 worked hypo-eutectoid steel through its critical range, and so leaving 

 insufficient time for the rejection of the full amount of ferrite. 

 While sorbitic pearlite is not quite so ductile as pearlite, which is 

 fully developed, it has a higher tenacity, so that had the foot of 

 this rail been subjected to the wheel-pressures instead of to the 

 head considerably better service could have been looked for. 



During the examination of the top specimen still another 

 irregularity was noticed at No. 5 (fig. 13). On the left are a 

 few pearlite crystals in the segregation with several small MnS 



