57
12-INCH STEEL В. L. RIFLED MORTARS.
Tube.
No. 7403.
n.r 1	12 M R־<״ T
Marks, m t, o Diameter, ".564.
Sectional area, .25 square inch. Gauged length, 3".
Remarks.
Initial load.
Elastic limit.
Tensile strength.
Successive
permanent
set.
Permanent set.
Inch.	Inch.
0. 0.
0. Í 0.
Successive elongation per inch.
Inch.
0.
.000100 .000233 .000334 . 000333 . 000167 . 000166 .000367 .000167 .000133 .009000 .001833 . 001334 .002166
Applied loads per square inch.	Elongation per inch.
Pounds.	Inch.
1,000	0.
5,000	.000100
10,000	.000333
20,000	.000667
30,000	.001000 •
35,000	. 001167
40,000	.001333
50,000	.001700
55,000	.001867
56,000	.002000
57,000	. 021000
58,000	.022833
59,000	.024167
60,000	. 026333
80,080	
General summary.
Tensile strength per square inch of original section...........................pounds.. 80,080
Elastic limit per square inch of original section................................do... 55,000
Elongation per inch after rupture..............................................inch..	. 2600
Elongation per inch under strain at elastic limit................................do... . 001867
Reduction in diameter at point of rupture........................................do...	.174
Reduction in area after rupture, per cent of original section......................... 52.2
Position of rupture............................................................ 15.״ from neck
Character of broken surface.............................................................. silky
Elongation of inch sections.................................................... 16.״ ,*42.״ ,20.״