(1. 長(zhǎng)安大學(xué) 材料科學(xué)與工程，西安 710064；
2. 西安賽特思邁鈦業(yè)有限公司，西安 710016；
3. 中國(guó)石油集團(tuán)石油管工程技術(shù)研究院，西安 710077；
4. 西北有色金屬研究院，西安 710016)
摘 要: 本文研究了近β-Ti合金、近α-Ti合金和(α+β)-Ti合金在0~-110 ℃、頻率為200 Hz簡(jiǎn)諧振動(dòng)過(guò)程中的振動(dòng)模量及裂紋擴(kuò)展行為，分析了溫度對(duì)簡(jiǎn)諧振動(dòng)中裂紋擴(kuò)展速率及位錯(cuò)分布的影響，揭示了裂紋擴(kuò)展機(jī)制。結(jié)果表明：低溫下的簡(jiǎn)諧振動(dòng)會(huì)加劇位錯(cuò)堆積與纏繞，從而增大阻尼，降低鈦合金的振動(dòng)回彈能力，提升鈦合金的減振性能。其中，近β-Ti合金的儲(chǔ)能模量整體比近α-Ti合金的低28.97%，其損耗模量和阻尼分別比(α+β)-Ti合金的高16.4%和9.88%，其低溫下的減振性能優(yōu)于其他兩種鈦合金。簡(jiǎn)諧振動(dòng)在β相內(nèi)產(chǎn)生的位錯(cuò)在相界累積并向相內(nèi)滑移，導(dǎo)致應(yīng)力集中和界面處微裂紋的產(chǎn)生，進(jìn)而發(fā)生穿晶斷裂。此外，伴隨著β相中二次裂紋的產(chǎn)生，裂紋尖端受到不同方向的阻力，消耗了額外的簡(jiǎn)諧振動(dòng)能量，尤其是當(dāng)溫度低于-60 ℃時(shí)，次生裂紋有效延緩了裂紋擴(kuò)展速率。簡(jiǎn)諧振動(dòng)在α相內(nèi)產(chǎn)生的位錯(cuò)首先在相內(nèi)被激活并不斷向相界堆積，導(dǎo)致相內(nèi)能量高于相界，裂紋發(fā)生沿晶擴(kuò)展。在-60~-110 ℃溫度區(qū)間，更低的損耗模量和阻尼使簡(jiǎn)諧振動(dòng)能量作用在裂紋沿晶擴(kuò)展上，增大了α相裂紋擴(kuò)展速率。
關(guān)鍵字: 典型鈦合金；儲(chǔ)能模量；損耗模量；阻尼；裂紋擴(kuò)展
（1. School of Materials Science and Engineering, Chang’an University, Xi’an 710064, China;
2. Xi’an Scitech Titanium Industry Co., Ltd., Xi’an 710016, China;
3. CNPC Tubular Goods Research Institute, Xi’an 710077, China;
4. Northwest Institute for Non-Ferrous Metal Research, Xi’an 710016, China）
Abstract:In this paper, the vibration modulus and crack propagation behavior of near β-Ti alloy, near α-Ti alloy and (α+β)-Ti alloy under harmonic vibration at the temperature range from 0 ℃ to -110 ℃ and frequency of 200 Hz were studied. The influence of temperature on crack propagation rate and dislocation distribution in harmonic vibration was analyzed, and the crack propagation mechanism was revealed. The results show that harmonic vibration at low temperature will aggravate dislocation accumulation and entanglement, thereby increasing damping, which reduces the vibration resilience of titanium alloys, can improve the vibration reduction performance of titanium alloys. The overall storage modulus of near β-Ti alloy is 28.97% lower than that of near α-Ti alloy, the loss modulus and damping are 16.4% and 9.88% higher than those of (α+β)-Ti alloy, respectively. The vibration reduction performance of near β-Ti alloy at low temperature is better than other two titanium alloys. The dislocations generated by the harmonic vibration in the β phase accumulate at the phase boundary and slip into the phase, leading to stress concentration and the generation of microcracks at the interface, and transgranular fracture occurs then. In addition, with the occurrence of secondary cracks in the β phase, the crack tip is subjected to resistance in different directions, which consumes additional harmonic vibration energy. When the temperature is lower than -60 ℃, the crack growth rate is delayed. The dislocations generated by the harmonic vibration in the α phase are first activated in the phase and continue to accumulate to the phase boundary, resulting in higher energy in the phase than that of the phase boundary, and intergranular fracture occurs then. In the temperature range from -60 ℃ to -110 ℃, the lower loss modulus and damping make the harmonic vibration energy act on intergranular fracture, which increases the crack propagation rate of α phase.
Key words: typical titanium alloy; storage modulus; loss modulus; tan delta; crack propagation
