48 JOURNAL AND PROCEEDINGS 



iuch of gray iron, malleable iron and mild steel castings, 



which serves to show the intermediate position of malleable 



iron. 



Tabic No. 1. 



Tensile Strength. 

 Material. I,bs. per Square Inch. Ductility. 



Gray Iron 20,000 to 30,000 .25 to .75% in 4 inches 



Maleable Iron 40,000 to 50,000 2.50 to 10.00% in 4 inches 



Mild Steel Castings. . . . 60,000 to 70,000 20.00 to 25,00% in 8 inches 



In regular commercial work it is not usual to meet 

 malleable iron that exceeds 50,000 pounds per square inch in 

 tensile strength, but the writer has met specimens in the form 

 of round test bars % inch diameter, having a strength of over 

 58,000 pounds and capable of 15 per cent, of elongation in a 

 length of 4 inches. Such material ma}' be very greatly de- 

 formed without being broken, as may be seen in Plate No. i. 

 In this are shown two round test bars of ^ inch section, 

 which have been bent by hammering as much as they would 

 stand without breaking. One of the .specimens represents 

 iron of unusual excellence, while the other, although well 

 suited to all uses for which malleable is applied, is of a more 

 ordinary quality. Before proceeding to a description of the 

 method of manufacture it may be of interest to quote from 

 the Standard American Specifications for Malleable Iron, 

 which were adopted in 1904 by the American Society for 

 Testing Materials, and which may be considered as represent- 

 ing good average practice. 



Tensile Test — The tensile strength of a standard test 

 bar, (i inch square) for castings under specification, shall 

 not be less than 40,000 pounds per square inch. The elonga- 

 tion measured in 2 inches shall not be less than 2]^ per cent. 



Transverse Test — The transverse test of a standard test 

 bar on supports 12 inches apart, pressure being applied at the 

 centre, shall not be less than 3,000 pounds, deflection being 

 at least % inch. 



These are requirements that can be readily met in any 

 well regulated foundr}^ and it is probable that by far the 

 largest part of the castings made at the present time are of a 



