SHEET NON-FERROUS METALS 



767 



per cent nickel. Each of these series included eleven tempers ranging^ 

 from annealed material to the hardness resulting from 10 B. & S. 

 gage numbers reduction. The samples were approximately 6 in. 

 square and \ in. thick. 



Complete series of samples comprising a fairly wide range of thick- 

 nesses were obtained for high-brass sheet in order to thoroughly 

 evaluate the methods of tests. These series were prepared in the 

 following B. & S. gages: Nos. 14, 16, 20, 24, 2S, 32 and 36. In each 

 gage the samples had the following hardnesses: Annealed and 2, 4, 

 6, 8 and 10 B. & S. gage numbers reduction. These rolling series, 

 therefore, included forty-two samples covering the usual commercial 

 range of hardness and the range of thickness of greatest importance 

 in telephone apparatus. These series were made under regular mill 

 conditions with careful supervision to insure representative rolling 

 practice and with complete records of the operations, special atten- 

 tion being given to accurate records of the percentage of reduction. 

 Care was taken to have the metal given approximately a 50 per cent 

 reduction before annealing to insure a uniform grain growth. The 

 temperature of annealing was equivalent to about 600° C. for one- 

 half hour, giving material of about average properties. These series 

 were rolled from four bars of the following compositions: 



The samples were flat strips 10 ft. long and 6 in. wide. 



The rolling series on clock brass were made in the following gages 

 and tempers: Nos. 12, 14, 16 and 18 B. & S. gages and 2, 4, 6 and 8 

 B. & S. gage numbers reduction. The composition was: Copper 

 61.63 per cent, zinc 36.75 per cent, lead 1.57 per cent, iron 0.05 per 

 cent. This material is so nearly like high-brass sheet in its prop- 

 erties that the data collected when added to that already available 

 were considered sufficient for the preparation of a set of requirements. 

 The tensile strength-percentage of reduction curve for high brass is 

 shown by Figure 10. The physical properties of high and clock brass 

 are shown by Tables I and II. 



As mentioned above, Rockwell hardness limits given have been 

 revised to agree with the more recently established Rockwell standards. 

 These limits have been verified by experience data collected on 



