Materials Science and Engineering: A ( IF 6.4 ) Pub Date : 2020-09-12 , DOI: 10.1016/j.msea.2020.140274 S. Sadeghpour , V. Javaheri , S. Bruschi , J. Kömi , P. Karjalainen
The effect of strain rate on flow behaviors of three beta Ti alloys with different beta phase stability was studied. The alloys were subjected to compression deformation at four strain rates ranging from 7 × 10−5 to 7 × 10−2 s−1 at room temperature. Microstructure evolution was characterized using laser scanning microscopy and electron backscattered diffraction methods. The effect of strain rate on the yield strength was found to vary between the alloys increasing with increased stability. The microstructural observations showed that the alloys exhibited different deformation mechanisms: deformation induced martensite formation, twinning and slip band formation. The strain hardening exponent (n) depended on the deformation mechanism, i.e., the stability. In the low and intermediate stability alloys showing martensite formation and combination of the deformation mechanisms respectively, n was about 0.07 independent of strain rate. In the alloy with the highest stability it was only 0.01 when the deformation mechanism was dislocation slip at low strain rates but increased significantly to ≈0.13 at high strain rates when also twinning occurred. The strain rate sensitivity factor (m) was about 0.014 and 0.017 for the low and intermediate stability alloy respectively independent of strain, but very low ≈ 0.002 for the highest stability alloy though increasing to ≈ 0.011 with increasing strain. Based on the experiments, the stability-strain rate-mechanism diagram was introduced to predict the effect of phase stability and strain rate on the deformation mechanism of beta Ti alloys.
中文翻译:
确定β钛合金变形行为的应变率和机械稳定性
研究了应变速率对三种不同β相稳定性的β-Ti合金流动行为的影响。合金以从7×10 -5到7×10 -2 s -1的四个应变率经历压缩变形。 在室温下。使用激光扫描显微镜和电子背散射衍射方法表征了微观结构的演变。发现应变速率对屈服强度的影响在合金之间随稳定性增加而变化。显微组织观察表明,合金表现出不同的变形机制:变形引起马氏体形成,孪晶和滑带形成。应变硬化指数(n)取决于变形机理,即稳定性。在分别显示马氏体形成和变形机制组合的低和中稳定性合金中,n约为0.07,与应变速率无关。在具有最高稳定性的合金中,其仅为0。当变形机制为位错时,01在低应变率下滑动,但在同时发生孪晶时,在高应变率下明显增加到≈0.13。对于低稳定性合金和中等稳定性合金,应变率敏感度系数(m)分别约为0.014和0.017,而对于最高稳定性合金,应变率敏感性系数(m)却非常低,≈0.002,尽管随着应变的增加而增加到≈0.011。在实验的基础上,引入稳定性-应变率-机理图,预测相稳定性和应变率对β-Ti合金变形机理的影响。002为最高稳定性合金,尽管随应变增加而增加到≈0.011。在实验的基础上,引入稳定性-应变率-机理图来预测相稳定性和应变率对β-钛合金变形机理的影响。002为最高稳定性合金,尽管随应变增加而增加到≈0.011。在实验的基础上,引入稳定性-应变率-机理图来预测相稳定性和应变率对β-钛合金变形机理的影响。