SHEET NON-FERROUS METALS 751 



the need for the development of a tester capable of higher precision 

 in the harder materials and also capable of making hardness tests 

 on material less than 0.020 in. thick is emphasized. 



The tensile strength limits are determined by the following pro- 

 cedure. The tension test results of the rolling series are plotted 

 against the actual percentage of reduction by cold rolling. Two 

 limiting curves are drawn in giving the minimum and maximum 

 tensile strength for all reductions covering the range of commercial 

 anneals. These two curves are based on years of experience with 

 these metals and also on the rolling series. The tensile strength 

 limits were taken from these curves for the theoretically correct 

 reduction for each temper. Rockwell hardness tests are made on the 

 grip ends of the tension test specimens, thus establishing the Rockwell 

 hardness-tensile strength relationship for the material. Having 

 established the tensile strength-reduction relationship, the corre- 

 sponding hardness values are obtained from the Rockwell hardness- 

 tensile strength curve. These limits are then subjected to trial on 

 a large number of shipments of material. 



The Rockwell test is considered a preliminary inspection test and 

 is mainly useful because of its economy of time and material. The 

 tension test, on the other hand, is considered the test upon which the 

 acceptance or rejection of the material is based. In practice, material 

 within the Rockwell hardness limits is accepted unless the hardness 

 reading is near or outside the hardness limits, in which case a tension 

 test is made. 



This paper covers high and clock brass sheet and four other alloys 

 of brass. One of these contains less lead than clock brass and is 

 designed for use where a material combining moderate drawing and 

 cutting properties is desired. Another has a nominal composition of 

 72 per cent of copper and 28 per cent of zinc. Grain size requirements 

 are given for two others mainly used for drawing purposes. One of 

 these consists of nominally 85 per cent of copper and 15 per cent of 

 zinc and the other of 75 per cent of copper and 25 per cent of zinc. 

 This paper also covers two nickel-silver alloys and two phosphor- 

 bronze alloys. 



The Rockwell hardness and tensile strength limits given for all of these 

 alloys other than high, clock and alloy E brass may be considered 

 tentative in view of the limited experience had with commercial 

 shipments of materials purchased in accordance with these limits 

 up to the present time. The requirements for high, clock and alloy E 

 brass are considered final. Alloy E brass has a lead content midway 

 between high and clock-brass. 



