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采用最大m值法、恒应变速率法在850~910℃下测试TC4钛合金板材的超塑性性能,分析了工艺参数对TC4钛合金板材的流动应力、应变速率敏感性指数和微观组织演变的影响。结果表明:该合金的最佳超塑性变形温度在850℃左右,在该温度下的基于最大m值法、恒应变速率法拉伸的伸长率均达到了最大且分别为1031%和631%,而在850℃下最大m值法拉伸能获得材料的最佳超塑性;当变形温度为850~910℃时,最佳变形速率0.00031~0.001 s~(-1);随变形温度的升高、应变速率的降低,该合金的流动应力降低,最大为70 MPa;该合金在850℃、应变ε=0.1条件下的应变速率敏感性指数m值最大且为0.58,并随着变形温度、应变量的增加而降低:超塑性变形中其内部发生了明显的动态再结晶,温度越高,晶粒越粗大。
The maximum m value and constant strain rate method were used to test the superplasticity of TC4 titanium alloy sheet at 850-910 ℃. The influence of technological parameters on the flow stress, strain rate sensitivity index and microstructure evolution of TC4 titanium alloy sheet was analyzed . The results show that the optimum superplastic deformation temperature of this alloy is about 850 ℃, and the maximum elongation at the constant strain rate method reaches the maximum at 1031% and 631% respectively at this temperature, , And the best superplasticity can be obtained by the maximum m value method at 850 ℃. When the deformation temperature is 850-910 ℃, the optimum deformation rate is 0.00031-0.001 s -1. With the increase of the deformation temperature High and strain rate. The flow stress of the alloy decreases to 70 MPa at maximum. The strain rate sensitivity index (m) at 850 ℃ and strain ε = 0.1 is the largest and is 0.58. With the deformation temperature, Decreased with the increase of the strain: In the superplastic deformation of its significant dynamic recrystallization occurred, the higher the temperature, the coarser the grain.