Ti-6Al-4V合金温变形性能研究

Warm Deformation Properties of Ti-6Al-4V Alloys

目的为了解决螺纹滚压加工缺陷问题,对Ti-6Al-4V合金进行温热环境变形研究,以期获得合适的温加工温度。方法通过Gleeble-3500型热模拟试验机进行了温拉伸和温剪切试验,应变速率为0.05~1 s^(−1),变形温度为100~600℃。分析了变形温度和应变速率对拉伸性能、剪切性能和延伸率的影响。研究了不同变形温度下Ti-6Al-4V合金微观组织演变情况。结果拉伸试样的流变应力随变形温度的升高而不断下降,且更快达到峰值应力。随应变速率的增加,流变应力上升。在温拉伸过程中,晶粒会发生转向以及拉长,且有再结晶现象出现。在300℃变形时组织中α相变形程度较为均匀。随变形温度的升高,合金组织中α相晶粒尺寸降低,晶粒的拉长变形程度增大。延伸率随着变形温度的升高整体呈现上升趋势,在300℃左右时存在一个区域塑性区。应变速率越高,试样的延伸率越低。试样的剪切强度随变形温度的升高而下降。剪切强度随应变速率的升高而逐渐提高。结论在300℃时组织中α相变形程度均匀,且塑性略高,为了避免较高变形温度时剪切强度过低材料出现粘连的情况,选择该温度为温滚压加工合适温度。

In order to eliminate thread rolling process defects,the work aims to study the deformation Ti-6Al-4V alloy in warm environment with a view to obtaining a suitable temperature for warm machining.The warm tensile and warm shear tests were carried out by Gleeble-3500 thermal simulation testing machine,with a strain rate of 0.05-1 s^(−1) and a deformation temperature of 100-600℃.The effects of deformation temperature and strain rate on tensile properties,shear properties and elongation were analyzed.The microstructure evolution of Ti-6Al-4V alloy under different deformation temperatures was studied.It was found that the rheological stress of the tensile specimen decreased with the increase of deformation temperature,and reached the peak stress faster.With the increase of the strain rate,the rheological stress increased.During the warm stretching process,the microstructure grains were turned and elongated,and the recrystallization occurred.At 300℃,the deformation degree ofαphase in the microstructure was relatively uniform.With the increase of deformation temperature,the grain size of theαphase decreased,and the elongation deformation degree of the grain increased.The elongation showed an upward trend with the increase of deformation temperature,and there was a regional plastic zone at about 300℃.The higher the strain rate,the lower the elongation of the specimen.The shear strength of the specimen decreased with the increase of deformation temperature.The shear strength gradually increased with the increase of the strain rate.At 300℃,the deformation ofαphase in the microstructure is uniform,and the plasticity is slightly high.In order to avoid the adhesion of the material with low shear strength at high deformation temperature,this temperature is more suitable for warm rolling processing.