冷却方式对TC21钛合金绝热剪切敏感性的影响

Effect of cooling ways on adiabatic shear sensitivity of TC21 titanium alloy

采用分离式Hopkinson Bar技术,对热处理后经3种冷却方式的TC21钛合金帽形试样进行动态剪切试验,结合宏观力学响应及微观形貌分析,研究冷却方式对TC21钛合金绝热剪切敏感性的影响。结果表明:热处理后的冷却方式对TC21钛合金在高应变率下的绝热剪切敏感性有较大影响;在相同应变率下,水冷试样的绝热剪切敏感性最高,炉冷试样的其次,空冷试样的最低;在4300 s^(-1)应变率下,水冷试样开裂程度较为严重,裂纹不仅在剪切带中延伸,还在基体中大幅度扩展,绝热剪切带最短、最窄;炉冷试样中裂纹尖端较为尖锐,且沿剪切带呈现了进一步扩展的趋势;空冷试样开裂程度较弱,裂纹没有呈现出进一步扩展的迹象,剪切带最长且最宽。

Using the technology of split Hopkinson Bar,the dynamic shear test on the hat-shape samples of TC21 titanium alloy, which was cooled separately by three cooling ways after heat treatment, was done, and the effects of cooling ways on adiabatic shear sensitivity of TC21 titanium alloy were studied by combining the dynamic mechanical response with the microstructural analysis of samples. The results show that the cooling ways of the alloy after heat treatment has great influence on the adiabatic shearing sensitivity of the TC21 titanium alloy. Under the same condition of strain rate, the subsequence of the adiabatic shearing sensitivity is water quenching samples, furnace cooling samples and air-cooling samples in turn according to sort in descending. At the strain rate of 4300 s^(-1), the sample by water quenching has the shortest and the most narrow adiabatic shear band. And its degree of cracking is the most severe among three kinds of samples. The crack expands not only along the shear band, but also in the matrix. The crack tip is sharper in the sample by furnace cooling, and takes on the expanding tendency along the shear band. The sample by air-cooling has the longest and the widest adiabatic shear band. Its degree of cracking is weak.