CAST IRON. 



383 



Thurston, in his book on " Iron and Steel," gives the 

 following values for the tensile strength of cast iron under 

 various conditions : 



TENSILE STRENGTH OF CAST IRON. (THURSTON.) 



Kind of Iron, and Conditions of 

 Preparation. 



Tensile Strength in tons per 

 square inch. 



Ordinary Conditions. 



Good pig iron 



Tough cast iron 



Hard , 



Good tough gun iron 



8-93 

 11-15 

 13-37 

 13-37 



Remelted cast iron. 



First melting 

 Second 

 Third 

 Fourth 



6-26 

 10-25 

 13-50 

 15-96 



Effect of varying time of fusion. 

 Fused for \ hour 



........ 



9 







7-97 



8-99 



10-90 



15-70 



Load-strain diagrams for cast iron in tension and 

 compression are shown on Fig. 185. The compression 

 curve is only partial. 



204. Compressive Strength of Cast Iron. The 



strength of cast iron in compression varies from 25 to 

 85 tons per square inch. 



Several important series of experiments have been 

 carried out by the American Foundrymen's Association, 

 with a view to determining a set of standard specifications 

 for cast iron. The first set of these clearly show that 

 specimens cast in small moulds give a higher result per 

 square inch than do larger specimens of the same material 

 mixture. In this series the crushing specimens were in 

 the form of cubes. 



