206 



BELL SYSTEM TECHNICAL JOURNAL 



Figure 16 illustrates the effect of a five die reduction on elongation 

 and tensile strength. It may be seen that the elongation drops very 

 rapidly at the first die when a reduction in area of about 42 >^ per cent 

 is made, and the tensile strength increases rapidly because of the cold 

 working of the metal. 



50,000 



40.000 



30, 000 0% 



0.250" 



0.104" 



This same figure shows the tensile strengths obtained when five, 

 six, and seven die reductions are used to produce line wire of .104 

 diameter from the same supply. Here the elongation loss is about the 

 same in each case, but the tensile strength is greater with the heavier 



