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对Ti-6Al-2Zr-1Mo-1V合金进行等温恒应变速率压缩试验,利用压缩试验数据对比Prasad失稳准则和唯象型失稳准则,发现2种准则均预测出合金在应变速率为0.32～10s-1范围内的塑性流动失稳现象,该失稳区随变形温度的降低具有逐渐向低应变速率范围扩展的趋势。经微观组织观察发现,Prasad准则不能预测到合金在750～800℃,0.001～0.0032s-1范围发生的局部流动和弯折失稳,而唯象型准则对合金在770～870℃、0.01～0.32s-1和900～950℃、0.32～3.16s-1区域出现的晶界裂纹、孔洞以及局部流动不能进行准确预测。结合2种准则的优缺点,提出预测合金塑性流动失稳的新方法。
The compression tests of Ti-6Al-2Zr-1Mo-1V alloy at constant temperature and constant strain rate were carried out. Comparing the Prasad instability criterion and the phenomenological instability criterion with the compression test data, The phenomenon of plastic flow instability in the range of 10s-1 tends to extend gradually to the low strain rate range with the decrease of deformation temperature. The results of microstructure observation show that the Prasad criterion can not predict the local flow and bending instability of alloy at 750-800 ℃ and 0.001-0.0032 s-1, The grain boundary cracks, holes and local flow in 0.32s-1 and 900 ~ 950 ℃, 0.32 ~ 3.16s-1 can not be predicted accurately. Combining the advantages and disadvantages of the two criteria, a new method of predicting the plastic flow instability of alloy is proposed.