SHEET NON-FERROUS METALS 801 



of the Rockwell hardness limits is subjected to the tension test. 

 Rejection of material is based solely on the tension test. 



Refinements in the application of the Rockwell hardness test as 

 an inspection instrument have been worked out and it is shown that 

 close agreement can be obtained between producer and consumer on 

 commercial shipments of material. 



The necessity for the adoption of a series of Rockwell standard 

 blocks covering the range of hardness of certain non-ferrous sheet and 

 the calibration of testing machines to these standards is emphasized. 



Grain-size limits are given for annealed brass of four compositions 

 and for one nickel-silver alloy. This is the most satisfactory method 

 of controlling the annealed material. 



Tentative tensile strength and Rockwell hardness limits for brass 

 alloy G, nickel-silver and phosphor-bronze alloys have been devel- 

 oped. These limits are considered preliminary until more complete 

 information on actual shipments of material is available. The limits 

 for high and clock brass are considered entirely satisfactory. 



A modified bend test has been presented as having considerable 

 value in determining the forming and drawing qualities of sheet 

 metals. 



APPENDIX I 



STANDARD TEST PROCEDURE FOR ROCKWELL HARDNESS 



TESTS 



Standard Test Blocks 



1. Standard test blocks are in the possession of the Bell Laboratories and sub- 

 standard blocks are calibrated from these blocks. These sub-standard blocks are 

 used to calibrate the Rockwell machines. All specifications are written in terms of 

 these standard blocks. Before a Rockwell machine is used for tests on metal sup- 

 plied to specifications it should be calibrated by the sub-standard block. 



Adjustments 



2. (a) Dash Pot. — 'The dash pot on the Rockwell tester shall be so adjusted that 

 the operating handle completes its travel in from five to ten seconds with no specimen 

 on the machine and with the machine set up to apply a major load of 100 kg. 



{b) Index Lever Adjustment. — -As specified in the Rockwell tester instruction book, 

 the following tests (and adjustments, if necessary) should be made. 



"Put a piece of material on the anvil and turn the capstan elevating nut to 

 bring the material up against the ball penetrator. Keep turning to elevate the 

 material until the hand feels positive resistance to further turning, which will be 

 felt after the 10-kg. minor load has been picked up and when the major load is 

 encountered. When excessive power would have to be used to raise the work 

 higher, take note of the position of the pointer on the dial. After setting the dial 

 so that C-0 and B-30 are at the top then: 



(i) If pointer stands between B-50 and B-70 no adjustment is needed. 

 {2) If pointer stands between B-45 and B-50 adjustment is advisable. 

 (J) If it stands anywhere else, adjustment is imperative. 



"As the pointer revolves several times when the work is being elevated it is 

 pointed out here that the readings mentioned apply to that revolution of the pointer 



