Study On Thermoplastic Deformation Behavior And Microstructure Evolution Of C17300 Alloy

Copper beryllium alloy（C17300）is one of the ideal materials for elastic components due to its excellent characteristics,such as excellent plasticity,strength and elasticity,no magnetism,and no spark on impacting.However,the cracking in the thermoplastic deformation caused by the high deformation resistance can lead to the difficulty in the plastic forming.Therefore,the object of this paper was the hot compressive deformation behavior and microstructure evolution of the C17300 alloy.The flow stress evolution behavior at different temperatures and strain rates was studied,and the hot working diagram was constructed based on the dynamic material model（DMM）.The main thermoplastic deformation mechanism of the alloy has been explored.The results of the research can provide the theoretical basis for the hot working process formulation of the C17300 alloy.The main conclusions are as follows:（1）The flow stress evolution behavior of C17300 alloy under different deformation conditions(deformation temperature range is 903～1063 K,strain rate range is 0.01～10 s^-1)was studied.The results show that the peak value of flow stress was negatively correlated with temperature when the strain rate was constant.The"sawtooth"jitter can be observed in the flow stress curve of the alloy at the temperature of 983 K、1023K、1063K with the strain rates of 1 s^-1 and 10 s^-1.（2）The Arrhenius model was used for the constitutive fitting of the C17300 alloy.The results show that the model generally fits well with the experimental results.The prediction accuracy of flow stress is the best at high temperature（1063 K）,and there may be a little error at low temperature（903～943 K）.（3）Based on the DMM theoretical model,the three-dimensional hot working diagram and two-dimensional slice diagram of the alloy were simulated and constructed,and the stable working region and instability working region of the alloy were obtained.The results show that the stable high power processing areas were mainly concentrated in high temperature and medium and low strain rate areas,while low power processing areas were mainly concentrated in low temperature and large strain rate areas.The rheological instability was mainly found in high strain rate areas.The optimum temperature range for hot working of the alloy was 1023～1063 K and the logarithm of strain rate was-1.75～-2 s^-1.（4）The main mechanism of the deformation process under different conditions in the hot compression test has been revealed.And the dynamic softening mechanism was mainly formed by the dynamic recrystallization.Continuous dynamic recrystallization（CDRX）dominated at 1023 K,and discontinuous dynamic recrystallization（DDRX）began at 1063 K.Microstructure analysis of the samples shows that the precipitated phase isβphase under 1023 K.The dispersed and unevenly distributed precipitations have different effects on the softening and hardening behavior in the process of dynamic precipitation at this temperature.That’s the reason why the"sawtooth"jitter of the flow stress curve can be observed.