Indentation creep of lead and lead-copper alloys
Stress exponent values have been determined in Pb and Pb-Cu alloys with small Sn, Se and Pd additions by indentation methods (long time hardness tests) to evaluate their applicability as compared with tensile tests. Homogeneous, fine grained alloys were obtained by induction melting and thermo-mechanical treatments. Grain size was 38–60 μm in alloys and 183 μm in pure lead. Stress exponent values, i.e. of 11–12 agree between different methods of derivation and, in fine grained material, with tensile methods. The largest differences in pure lead, i.e. 10–11 versus 7–8 are attributed to high strain rates when indentation size is comparable to grain size. In all cases indentation and tensile tests indicate the same deformation mechanism, namely slip creep. The indentation test is thus considered useful, within limits, to acquire information on the deformation mechanism.
KeywordsTensile Test Deformation Mechanism High Strain Rate Stress Exponent Indentation Test
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