SYMPOSIA PAPER Published: 01 January 1945
STP42569S

Residual Stress in Caliber 0.30 Cartridge Cases

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An investigation has been made of residual stress in the head and body of caliber 0.30 cartridge cases. The head was divided into four ring-like sections which were cut off by a jeweler's saw. Spring-out was measured after a radial cut had relieved the circumferential bending moment. The residual stress corresponding to the observed spring-out was calculated by formulas in which the computed stress was a function of wall thickness. All rings sprang open, indicating compressive stress on the inner wall and tensile stress on the outer wall. The production stress-relief anneal of 475 F. for 45 min. reduced the stress to almost half. The priming and crimping operation, however, again raised the stress, especially in the flange section. The effect of stress-relief heat treatments on residual stresses in the body of caliber 0.30 cartridge cases was investigated by the split-ring method. Although this method did not reveal any large stresses in the body, the neck before mouth anneal was found to contain a computed stress of 30,000 psi. at the surface. This value was reduced to 15,000 psi. in 120, 30, and 15 min. at 400, 475, and 500 F., respectively.

Author Information

Rosenthal, H.
Ordnance Laboratory, Frankford Arsenal, Philadelphia, Pa.
Mazia, J.
Ordnance Laboratory, Frankford Arsenal, Philadelphia, Pa.
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Details
Developed by Committee: B05
Pages: 120–134
DOI: 10.1520/STP42569S
ISBN-EB: 978-0-8031-5903-7
ISBN-13: 978-0-8031-6057-6