Study of the Effect of Processing Variables on the Mechanical Properties of 5 Inch Cartridge Cases.

摘要

The yield strength of 5 inch cartridge cases (1030 steel) has been previously shown to be dependent upon the preparation method used for the test samples. The samples prepared by a procedure used by the Navy were roll-straightened and stress relieved and the samples prepared by an Army method were straightened and not stress relieved. The samples prepared by the Navy test method gave a relatively high yield strength compared to samples prepared by the Army method. It is clear from this previous work that if yield strength is to be a satisfactory acceptance criterion, standard specimen preparation and mechanical test procedures are necessary. The aims of this current program have been to determine in detail the effect of different sample preparation procedures on the yield strength and to recommend a standard procedure. In summary, it is found that stress relieving the roll-straightened specimens produces strain aging which results in an increased yield strength and a restoration of a distinct yield point. The Navy method will better represent the actual yield strength of the case if the stress relief treatment is omitted as no increase in yield strength was measured due to various straightening techniques.