TC4钛合金流动软化行为及本构模型研究  

Flow Softening Behavior and Constitutive Equation of TC4 Titanium Alloy during Hot Deformation

作　　者：徐勇[1,2] 杨湘杰[1] 何毅[1] 杜丹妮[1] 

机构地区：[1]南昌大学,江西南昌330031 [2]南昌航空大学,江西南昌330063

出　　处：《稀有金属材料与工程》2017年第5期1321-1326,共6页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(51164030);航空科学基金(2014ZE56015)

摘　　要：利用Gleeble-3500热模拟试验机进行等温恒应变速率热压缩实验,研究了TC4钛合金在温度800~950℃、应变速率0.001~10 s^(-1)条件下的流动软化行为。研究发现随变形温度降低和应变速率增大TC4钛合金的流动软化程度增大,且800~850℃、应变速率1~10 s^(-1)变形时的流动软化主要是塑形流动失稳引起的,温度900~950℃、应变速率0.001~0.1 s^(-1)条件变形时,流动软化主要是片状α相的等轴化引起的。引入应变对材料常数α、n、A和Q的影响,建立了考虑应变的TC4钛合金Arrhenius本构方程,建立的本构模型精度较好,在800,850℃和10 s^(-1)条件以及在900,950℃和0.1 s^(-1)条件下,模型平均绝对误差分别为4.2%和4.3%。TC4钛合金的平均变形激活能为403 kJ/mol,平均应变速率敏感指数为0.26。Hot compression tests were conducted on TC4 titanium alloy at different temperatures in a range of 800-950 ℃ and at different strain rates in the range of 0.001-10 s^-1 Flow softening behavior of this alloy was investigated. Results show that the flow softening degree increases with the increasing strain rate and the decreasing temperature. Meanwhile, softening is mainly attributed to flow instability at temperatures of 800 and 850 ℃, strain rates of 1 and 10 s1. Conversely, softening is dominated by globularization of lamellar alpha at temperatures of 900 and 950℃, strain rates of 0.001, 0.01 and 0.1 s^-1 In addition, the effect of strain is incorporated in the Arrhenius equation by considering the effects of strain on material constants including a, n, .4 and Q. The calculated flow stresses are compared with the experimental results. It is indicated that this model gives precise estimation for the flow stress, especially at 800-850 ℃ and 10 s^-1, 900-950℃and 0.1 sL The average deformation activation energy is about 403 kJ/mol and the average strain rate sensitivity exponent of TC4 alloy is 0.26.

关 键 词：TC4钛合金 流动软化 本构方程 热变形 

分 类 号：TG146.23[一般工业技术—材料科学与工程]