Ti-6Al-7Nb合金高温塑性变形行为及热加工图研究

Study on High Temperature Plastic Deformation Behavior and Hot Working Map of Ti-6Al-7Nb Alloy

摘要:

本文以Ti-6Al-7Nb合金为研究对象，采用Gleeble-3500热模拟压缩试验机进行不同温度和应变速率压缩试验。分析了Ti-6Al-7Nb合金在变形温度1023 K、1073 K、1123 K、1173 K，应变速率为0.005 s-1、0.05 s-1、0.5 s-1、5 s-1和10 s-1，最大变形量为60%下的高温变形行为及热加工特性。结果表明：变形温度与应变速率对Ti-6Al-7Nb合金的流动应力影响较大，其中应变速率是影响加工硬化过程的主要因素。Ti-6Al-7Nb合金在发生热塑性变形时后的物相主要有：初生α相、片层状α相、次生α相、片层状β相以及发生球化的初生α相等。Arrhenius本构方程模型适用于低温低应变速率和高温高应变速率形变条件的Ti-6Al-7Nb合金高温变形。利用MATLAB构建计算确定了合金最佳塑性变形区间为：应变速率0.0067 s-1-0.1353 s-1和温度1100-1173 K，在该区间有可能获取Ti-6Al-7Nb合金最佳的塑性变形工艺参数。

Abstract:

In this paper, Ti-6Al-7Nb titanium alloy was studied. The Gleeble-3500 thermal simulation compression testing machine was used to carry out compression tests at different temperatures and strain rates. The high temperature deformation behavior and hot working characteristics of Ti-6Al-7Nb titanium alloy at deformation temperatures of 1023 K、1073 K、1123 K、1173 K and strain rates of 0.005 s-1, 0.05 s-1, 0.5 s-1, 5 s-1, 10 s-1, and the maximum deformation is 60%. The results show that deformation temperature and strain rate change the flow stress curve of Ti-6Al-7Nb titanium alloy, and have complex effects on work hardening and flow softening during the hot plastic deformation of the alloy. The main phases of Ti-6Al-7Nb titanium alloy after hot plastic deformation are as follows: primary α phase, lamellar α phase, secondary α phase, lamellar β phase and primary α phase with spheroidization. The strain rate has a significant effect on the deformation hardening effect of the alloy. The Arrhenius constitutive equation model is suitable for high temperature deformation of Ti-6Al-7Nb titanium alloy under high strain rate, low temperature and high temperature deformation conditions. The optimum plastic deformation range of Ti-6Al-7Nb alloy is determined by MATLAB construction and calculation: the strain rate is 0.0067 s-1-0.1353 s-1 and the temperature is 1100-1173 K. It is possible to obtain the best plastic deformation process parameters of Ti-6Al-7Nb titanium alloy in this region.