ON STRESS DISTRIBUTIONS IN ENGINEERING MATERULS. 



161 



Dr. F. C. Lea and Mr. C. E. Stromeyer have joined the Com- 

 mittee during the year. 



The Committee ask to be reappointed, with a grant of lOOL 



Appendix A. 



Report on Static Tests of a Mild Steel received from the British 

 Association Stress Committee. 



By Mr. W. A. Scoble. 



The preliminary tensile tests made by Mr. Cook showed that the 

 yield stress varied from 23'95 tons per square inch for the -ft- bar 



Fig. 1. 



a 

 o 



ns 

 o 



44 



i' r 



Extension in inches, 



to 13*40 tons per square inch for the liV-inch bar. To compare the 

 results of static tests on the different bars it was clear they should be 

 brought to a uniform condition, or the advantage of having them of the 

 same steel would be neutralised. At this time the question of annealing 

 had not been raised, but the specimens for which the test results are 

 given below were all subjected to the following treatment. The 

 specimens were cut from a -M-inch round bar, placed in an electric 

 furnace and heated with the furnace to a temperature of about 900° C. 

 The bars were allowed to cool inside the furnace. 



Tension Test. — The specimen had screwed ends and was turned 

 down to 0'499-inch diameter. There was a very slight indication that 

 the strain increased more rapidly than the stress. The extensometer 

 used was of special design, and the measurement of elongation was 

 certainly correct to within 0'5 per cent. 



Yield stress 10'04 tons per sq. inch. 



Maximum stress 20-89 ,, „ „ 



Elongation on 5 inches (10 diameters) . 36 per cent. 

 Reduction in area at fracture . . . 69-6 percent. 

 ' E ' 28,800,000 lbs. or 12,850 tons per sq. inch. 

 1915. U 



