STRAIN HARDENING INHOMOGENEITY OF COPPER IN TENSILE AND CREEP TESTS.

A comparative analysis was made of the intensity of development of strain hardening inhomogeneity in the samples during tensile and creep tests. It was demonstrated that creep favorably affects the development of strain hardening inhomogeneity. For example, the inhomogeneity index DELTA HM at a strain epsilon equals 20. 6% was 66. 9 MN/m**2 in simply extended samples and 108. 0 MN/m**2 in samples subjected to creep. At strains epsilon less than 20% a band inhomogeneity was observed, while at higher strains stable 'islands' of more hardened metal occur, which finally leads to necking in the sample. The strain rate sensitivity is considerably higher in layers close to the sample surface. Central layers harden practically independently of the extension rate.