Li Dechong, Zhu Haihui, Qu Shuguang, Lin Jiatian, Ming Ming, Chen Guoqing, Zheng Kailun, Liu Xiaochuan
School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China.
School of Mechanical Engineering, Dalian University of Technology, Dalian 116024, China.
Materials (Basel). 2023 Jan 13;16(2):810. doi: 10.3390/ma16020810.
This paper presents a systematic study of heating effects on the hot deformation and microstructure of dual-phase titanium alloy Ti-6Al-4V (TC4) under hot forming conditions. Firstly, hot flow behaviors of TC4 were characterized by conducting tensile tests at different heating temperatures ranging from 850 °C to 950 °C and heating rates ranging from 1 to 100 °C/s. Microstructure analysis, including phase and grain size, was carried out under the different heating conditions using SEM and EBSD. The results showed that when the heating temperature was lower than 900 °C, a lower heating rate could promote a larger degree of phase transformation from α to β, thus reducing the flow stress and improving the ductility. When the temperature reached 950 °C, a large heating rate effectively inhibited the grain growth and enhanced the formability. Subsequently, according to the mechanism of phase transformation during heating, a phenomenological phase model was established to predict the evolution of the phase volume fraction at different heating parameters with an error of 5.17%. Finally, a specific resistance heating device incorporated with an air-cooling set-up was designed and manufactured to deform TC4 at different heating parameters to determine its post-form strength. Particularly, the yield strength at the temperature range from 800 °C to 900 °C and the heating rate range from 30 to 100 °C/s were obtained. The results showed that the yield strength generally increased with the increase of heating temperature and the decrease of heating rate, which was believed to be dominated by the phase transformation.
本文对双相钛合金Ti-6Al-4V（TC4）在热加工条件下热变形和微观组织的热效应进行了系统研究。首先，通过在850℃至950℃的不同加热温度和1至100℃/s的加热速率下进行拉伸试验，对TC4的热流动行为进行了表征。使用扫描电子显微镜（SEM）和电子背散射衍射（EBSD）在不同加热条件下进行了微观组织分析，包括相和晶粒尺寸。结果表明，当加热温度低于900℃时，较低的加热速率可促进更大程度的从α相向β相的转变，从而降低流动应力并提高延展性。当温度达到950℃时，较大的加热速率有效地抑制了晶粒生长并提高了成形性。随后，根据加热过程中的相变机制，建立了一个唯象相模型来预测不同加热参数下相体积分数的演变，误差为5.17%。最后，设计并制造了一种结合风冷装置的电阻加热装置，以在不同加热参数下使TC4变形，从而确定其热加工后的强度。特别地，获得了800℃至900℃温度范围和30至100℃/s加热速率下的屈服强度。结果表明，屈服强度通常随着加热温度的升高和加热速率的降低而增加，这被认为主要由相变主导。
