冷卻方式對(duì)TC21鈦合金絕熱剪切敏感性的影響

冷卻方式對(duì)TC21鈦合金絕熱剪切敏感性的影響Effect of cooling ways on adiabatic shear sensitivity of TC21 titanium alloy

采用分離式Hopkinson Bar技術(shù)，對(duì)熱處理后經(jīng)3種冷卻方式的TC21鈦合金帽形試樣進(jìn)行動(dòng)態(tài)剪切試驗(yàn)，結(jié)合宏觀力學(xué)響應(yīng)及微觀形貌分析，研究冷卻方式對(duì)TC21鈦合金絕熱剪切敏感性的影響。結(jié)果表明：熱處理后的冷卻方式對(duì)TC21鈦合金在高應(yīng)變率下的絕熱剪切敏感性有較大影響；在相同應(yīng)變率下，水冷試樣的絕熱剪切敏感性最高，爐冷試樣的其次，空冷試樣的最低；在4300 s-1應(yīng)變率下，水冷試樣開裂程度較為嚴(yán)重，裂紋不僅在剪切帶中延伸，還在基體中大幅度擴(kuò)展，絕熱剪切帶最短、最窄；爐冷試樣中裂紋尖端較為尖銳，且沿剪切帶呈現(xiàn)了進(jìn)一步擴(kuò)展的趨勢(shì)；空冷試樣開裂程度較弱，裂紋沒(méi)有呈現(xiàn)出進(jìn)一步擴(kuò)展的跡象，剪切帶最長(zhǎng)且最寬。

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.

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