置氢TC17钛合金组织演变规律及高温变形行为

Microstructure Evolution and Deformation Behavior of Hydrogenated TC17 titanium alloy

摘要:

为了改善了TC17钛合金热加工性能,对TC17钛合金进行了置氢处理,通过金相观察和X射线衍射分析,研究了置氢后TC17钛合金的微观组织及相转变规律,在变形温度800 ~ 860℃、应变速率0.001 ~ 0.1s_^-1的条件下,对置氢TC17钛合金进行了高温压缩实验,研究了置氢TC17钛合金的热变形行为,并对其热变形激活能进行了计算分析。结果显示,TC17钛合金原始组织为典型的网篮组织,由α+β相组成,随着氢含量的增加,针状α相数量减少,β相增多,当氢含量超过0.40wt%时,钛合金中依次出现了γ氢化物和δ氢化物。置氢TC17钛合金不仅是温度敏感型材料、速率敏感型材料,也是氢含量敏感型材料,在氢含量0.2wt%时,峰值应力达到最小值,与原始合金相比,变形温度可降低40℃,应变速率可提高1个数量级。同时,氢含量0.2wt%的TC17钛合金变形激活能也达到最小值162KJ/mol,其热变形软化机制为动态回复。

Abstract:

In order to improve the hot workability of TC17 titanium alloy, TC17 titanium alloy was hydrogenated. Through metallographic observation and X-ray diffraction analysis, the microstructure and phase transformation law of TC17 titanium alloy were studied after hydrogenated treatment. Under the conditions of deformation temperature of 800-860℃ and strain rate of 0.001-0.1s_^-1, the isothermal compression tests of hydrogenated TC17 titanium alloy were carried out. The deformation behavior of the hydrogenated TC17 titanium alloy was studied, and the thermal activation energy was calculated and analyzed. The results show that the microstructure of TC17 titanium alloy is a typical net basket structure, which is composed of α+β phase composition. With the increasing of hydrogen content, the volume fraction of acicular α phase decreases, and the volume fraction of β phase increases. When the hydrogen content exceeds 0.40wt%, the γ and δ hydrides separate out. The hydrogenated TC17 titanium alloy is not only a temperature sensitive material, a rate sensitive material, but also a hydrogen content sensitive material. When the hydrogen content is 0.2wt%, the peak stress reaches the minimum value. Compared with the original alloy, the deformation temperature can be deincreased by 40℃ and the strain rate can be increased by one order of magnitude. At the same time, the thermal activation energy of TC17 titanium alloy with 0.2wt% hydrogen content also reaches the minimum value of 162KJ/mol, and its thermal deformation softening mechanism was dynamic recovery.