Abstract
Compression tests were carried out on two compositions of Cu–Sn bronze: Cu–9·2Sn and Cu–9·1Sn–0·26Zn (wt-%). The experiments were performed at temperatures from ambient up to 750°C and at nominal (initial) strain rates in the range 10-3 to 10-1 s-1. The measured data were converted into true stress–true strain curves; these displayed yield drops as well as single peaks (or maxima) at higher temperatures and lower strain rates. The mean rate sensitivity applicable to the curves was 0·25. Optical metallography indicated that dynamic recrystallisation of the ‘grain refinement’ type was taking place at the higher temperatures and proceeded by necklace formation. Electron backscattered diffraction measurements were also carried out; these revealed that twinning plays an important role in these materials. The present results show that the progress of recrystallisation is considerably slower than in OFHC copper and that the recrystallised grain size is appreciably finer. These observations, taken together, all indicate that the high temperature flow behaviour of the tin bronzes is controlled by solute drag and is not of the conventional ‘pure metal’ type.
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