ON THE INFLUENCE OF SILICON ON THE PROPERTIES OF STEEL. 273 



form silicon may take in cast-iron or steel, Mr. Keep considers that 

 whether it exists in a state corresponding to graphitic carbon, and 

 mechanically mixed with the remaining mass, is still a question in dispute. 

 Mr. Holgate of Darvven, also, in the paper before referred to, after making 

 many analyses, says he has never found any evidence as to the existence 

 of graphitic silicon in such alloys, though he has noticed some slight 

 difference in the behaviour of silicon when dissolved in acids. Mr. Turner 

 in his paper some two years ago, after carefully investigating this point 

 both by means of experiments of his own and those of Sir Frederick Abel, 

 Mr. Snelus, and others, says that it may at any rate be considered, in a 

 vast majority of cases at least, that silicon has only one form. Finally, 

 therefore, the practical metallurgist has at present, apparently, no means 

 of readily determining this point, although he may have reason to think 

 that silicon does vary its form in either cast-iron or steel. 



In metallurgical literature but little information is to be found as to 

 the effect of silicon upon iron. Mr. Howe in his excellent work on ' The 

 Metallurgy of Steel ' gives an excellent resume of what has appeared. 

 Some fourteen years ago in America good results were promised by a 

 process, which was to use ' codorus or silicon ore,' as it was termed. This 

 was to dephosphorise or neutralise the phosphorus in the metal under 

 treatment. Only a few years back the writer had reason to investigate 

 this matter in America, but found that this so-called puddled silicon iron 

 or silicon steel contained no silicon. The whole matter was well sum- 

 marised by the well-known metallurgist, Holley, of America, who said, 

 or rather sang, of it : — 



There was an old man of Codorus 



Who said he took out the phosphorus 



So the iron he puddled and with chemicals muddled, 



But the puddling took out the phosphorus. 



Referring now to the consideration of silicon alloyed with the metal 

 ii'on, the common belief has been that steel which has to be used in its 

 forged state should contain practically none or as small an amount as 

 possible. Any quantity exceeding -10 per cent., or up to -20 per cent, at 

 most, has been considered to be highly injurious. 'Give a dog a bad 

 name ' is well illustrated in the present case, as will be seen from the 

 results and tests given. At any rate it may be safely said that silicon 

 has been blamed in a somewhat hasty manner. This blame may be well 

 deserved in alloys of carbon, silicon, and iron, as such alloys as regards 

 ductility have, no doubt, proved unreliable and of little value ; but the 

 blame was put at the door of silicon, whereas it is now proved that 

 silicon alloyed with iron, provided carbon is absent, or only present in 

 small amounts, gives good tests as to toughness and malleability. It will 

 be seen that 1^ or even 2 per cent, may be present and yet the material 

 possess 25 to 30 per cent, elongation ; whereas the same percentage of 

 carbon alloyed with iron would give a product barely malleable, and one 

 possessing practically no properties ot elongation under tensile stress 

 Whilst therefore the common belief that alloys of carbon, silicon, and 

 iron are brittle, or even dangerous, is quite correct, the cause is not due 

 to silicon only, but to the combination of silicon with carbon and iron — a 

 I Mse parallel, to some extent, to that pointed out by the well-known Terre 

 Noire Company's experiments, where it was proved that phosphorus may 

 present in iron provided the carbon is low and the manganese high; a 

 (fc — that is, as regards phosphorus — still more prominent in wrought irons. 

 1889. T 



