多次压缩对TC4钛合金高温变形行为影响的研究

Effect of Multi-time Compression on High Temperature Deformation Behavior of TC4 Titanium Alloy

采用Gleeble-3500热模拟试验机分别以单次及多次压缩在变形温度900~1050℃,以不同的应变速率对TC4钛合金进行了变形试验。结果表明:单次压缩变形时,流动应力随着应变速率的增大而增大,随温度的升高而降低,在变形温度900、950℃观察到了明显的应力改变,这与900、950℃变形时发生魏氏组织转变相关。同时,当温度在900、950℃时,原始组织呈压扁与破碎状;当温度高于950℃时,大的变形量下易生成魏氏组织。多次压缩变形时,当变形温度为900℃时得到了片层组织形貌特征,而当变形温度高于950℃时生成了魏氏组织,这种微观形貌特征会影响材料的力学性能。因此,为了改善合金的塑性变形能力,将变形温度尽量控制在900℃,以避免魏氏组织的形成。

The Gleeble-3500 thermal simulation testing machine was used to perform compression deformation tests of the TC4 titanium alloy at different strain rates and deformation temperature of 900-1050℃in single-time and multi-time compression.The results show that the flow stress increases with the increase of deformation rate and decreases with the increase of temperature during single-time compression.A significant stress change is observed between the deformation temperature of 900°℃and 950°C,which is related to the Welshmannesian microstructure transformation during 900℃and 950°℃deformation.At the same time,when the temperature is 900°C and 950°℃,the original microstructure is squashed and crushed.When the temperature is higher than 950'C,Widmanstatten structure is easy to form under large deformation.After multi-time deformation at 90oC,the lamellar structure morphology characteristics are obtained.However,when the deformation temperature is higher than 950C,the Widmannian microstructure is formed,which will affect the mechanical properties of the material.Therefore,in order to improve the plastic deformation ability of the alloy,the deformation temperature should be controlled at 900C to avoid the formation of Widmanstatten structure.