J OURN AL 



OF THE 



NEW-YORK MICROSCOPICAL SOCIETY, 



Vol. VII. OCTOBER, 1891. No. 4. 



STRUCTURE IN STEEL. 



BY P. H. DUDLEY. 

 iRead June i^th, iSgi.) 



The subject is so vast and important that I shall confine my 

 remarks principally to rail steel. Besides the iron forming the 

 basis of ordinary steel rails, they have a large range in chemical 

 composition, as shown by the following table : 



Parts of I per cent. 



Carbon 25 to .50 



Manganese 30 to i .50 



Silicon 04 to ,30 



Phosphorus 03 to .15 



Sulphur 04 to .10 



Copper 10 to .80 



Traces of other minerals are present. 



This alloy, being formed by fusion and cast, is of course crys- 

 talline in structure. The texture will be fine or coarse, accord- 

 ing to composition, size of ingot, rapidity of solidification, amount 

 of mechanical work given to the metal in reducing to the sec- 

 tion of the rail, shape and size of the latter, and the temperature 

 at which the rail is finished. In a section of rail of which the 

 ingot or bloom was maintained at too high temperature, the crys- 

 tallization becomes coarse and often sharply defined, the matrix 

 enclosing or joining the crystals weak and breaks upon the sur- 

 face, instead of pulling out the portions which penetrated the 

 large pseudo-crystals. The delicate matrix enclosing the pseudo- 

 crystals is shown in specimen No. i with low powers, but few 



