PROPERTIES OF STRUCTURAL METALS. 43 



structure during cooling. Aside from these considerations its 

 influence is not felt in a marked degree in the rolling-mill, for 

 it has no disastrous effect upon the toughness of red-hot 

 metal when the content does not exceed . 15 per cent." 



A discussion of the effects of phosphorus in steel by 

 Howe's " Metallurgy of Steel," and summarized by Mr. 

 Campbell, is as follows : 



"(i) The effect of phosphorus on the elastic ratio, as on 

 elongation and contraction, is very capricious. 



11 (2) Phosphoric steels are liable to break under very 

 slight tensile stress if suddenly or vibratorily applied. 



" (3) Phosphorus diminishes the ductility of steel under a 

 gradually applied load as measured by its elongation, contrac- 

 tion, and elastic ratio when ruptured in an ordinary testing- 

 machine, but it diminishes its toughness under shock to a still 

 greater degree, and this it is that unfits phosphoric steels for 

 most purposes. 



" (4) The effect of phosphorus on static ductility appears 

 to be very capricious, for we find many cases of highly phos- 

 phoric steel which show excellent elongation, contraction, and 

 even fair elastic ratio, while side by side with them are others 

 produced under apparently identical conditions but statically 

 brittle. 



"(5) If any relation between composition and physical 

 properties is established by experience, it is that of phosphorus 

 in making steel brittle under shock; and it appears reason- 

 ably certain, though exact data sufficing to demonstrate it are 

 not at hand, that phosphoric steels are liable to be very brittle 

 'under shock, even though they maybe tolerably ductile static- 

 ally. The effects of phosphorus on shock-resisting power, 

 though probably more constant than its effects on static duc- 

 tility, are still decidedly capricious. . . ." 



Mr. Campbell's conclusion in regard to the effects of 

 phosphorus in the composition of steel, and the limit to be 



