:i,so 



STRENGTH OF STEEL. 



Mr. Abbott further gives the average modulus of 

 elasticity for all the bars tested as 10,900 tons per 

 square inch. It will be seen that the elastic limit in com- 

 pression is not very different from the elastic limit in tension. 



Results by other investigators accord fairly well with 

 those just given, although in some cases the tensile 

 strength gets up to 45 tons per square inch. . Mr. Hill's 

 results show that, although the tensile strength is not 

 greatly affected by annealing, the ductility, as shown by 

 the extension and reduction, is greatly increased. 



Other Special Steels. Tungsten, when added to 

 steel in the proportion of about 8 per cent., produces a 

 metal of great natural hardness, which is not increased by 

 quenching, nor diminished by annealing. Tungsten steel 

 requires great care in working. 



60 



50 



40 



30 



20 



10 



200 400 600 800 

 Temperature. Degrees F. 



1000 1200 



FIG. 184] EFFECT OF TEMPERATURE ON THE STRENGTH OF 

 HIGH CARBON STEEL. (JOHNSON.) 



Aluminium, added to good-class wrought iron, enables 

 the metal to be formed into castings, called Mitis castings, 



