IKON AND STEEL 



243 



Materials has recommended the following values for the strength of 

 steel castings (allowable variation 5000 pounds). 



TENSILE STRENGTH 

 lb./in.2 



Soft castings 



Medium castings ........... 



Hard castings ........ ...... 80000 



In the cold bending test the material must be bent about a diameter 

 of 1 in. through 120 for the soft, and 90 for the medium, without 

 showing cracks or signs of failure.* 



The Ordnance Department of the United States Army in the gen- 

 eral specifications for 1903 gives the following requirements for steel 

 castings and forgings. 



194. Modulus of elasticity of steel and wrought iron. The mod- 

 ulus of elasticity of steel and wrought iron is about the same in 

 tension as in compression. For steel, 30,000,000 lb./in. 2 is usually 

 taken as a good average value for tension and compression, and 

 about two fifths of this amount, or from 10,000,000 to 12,000,000 

 lb./in. 2 , for shear; for loads below the elastic limit it is always the 

 ratio of stress to deformation. 



From a series of tests reported in the Trans. Amer. Soc. Civ. Eng., 

 Y<>1. XVII, pp. 62-63, the following average values are found. 



MATERIAL 



MODULUS OF ELASTICITY 

 Ib./m. 2 



Proc. Amer. Soc. for Testing Materials, 1903. 



