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蠕变或应力松弛被认为是钛合金板材热成形降低回弹的主要机理。目前对热校形阶段中的蠕变与应力松弛的区别及联系尚缺乏深入研究。本文主要进行了钛合金高温短时蠕变及应力松弛实验,利用TEM对实验后的显微组织进行了观察。分别研究了温度、应力及时间对蠕变和应力松弛行为的影响规律,从蠕变率-时间和蠕变-时间角度建立了蠕变与应力松弛之间的联系。研究表明:钛合金在低温低应力下蠕变以原子扩散为主,高温高应力下以位错滑移和攀移为主,而应力松弛在不同温度时均以位错攀移为主要变形机制,基于蠕变数据预测的应力松弛行为与实验结果符合较好。
Creep or stress relaxation is considered to be the main mechanism by which hot forming of titanium alloy plates reduces the springback. At present, the difference and connection between creep and stress relaxation in hot camber stage are still lack of further study. In this paper, short-term high temperature creep and stress relaxation experiments of titanium alloy were carried out. The microstructure of the alloy was observed by TEM. The effects of temperature, stress and time on the creep and stress relaxation behaviors were studied respectively. The relationship between creep and stress relaxation was established from the aspects of creep rate - time and creep - time. The results show that the creep of titanium alloy is dominated by atomic diffusion at low temperature and low stress, dislocation slip and climbing are the main stresses under high temperature and high stress, while the stress relaxation is dominated by dislocation climbing at different temperatures The predicted stress relaxation behavior based on creep data is in good agreement with the experimental results.