摘要
基于等温恒应变速率热压缩实验,探究了新型Ti-4Al-5Mo-6Cr-5V-1Nb合金在变形温度700~900℃、应变速率0.001~1.000 s;条件下的热变形行为。通过真应力-真应变曲线分析了变形参数对合金力学性能的影响规律,选用修正的Arrhenuis双曲正弦函数模型推导了耦合应变的本构方程,基于动态材料模型及Prassd流变失稳准则构建了热加工图。结果表明:Ti-45651合金为温度、应变速率敏感型材料,其峰值应力及稳态流变应力随变形温度的增加逐渐降低,随应变速率的增大呈增加趋势。流变曲线在两相区呈动态再结晶型,在β单相区为动态回复型。本构方程计算可得两相区平均热变形激活能为280.023 kJ·mol^(-1),远大于纯钛的自激活能,说明两相区的热变形软化机制以动态再结晶为主。β单相区平均热变形激活能为202.564 kJ·mol^(-1),稍大于纯钛的自激活能,说明其软化机制以动态回复为主。该合金的公共失稳区为700~800℃,0.010~1.000 s;和850~870℃,0.320~1.000 s^(-1),该区域的功率耗散效率(η)低至0.15,且有绝热剪切带等失稳组织出现;其公共峰值变形区为700~770℃,0.001~0.010 s;和790~810℃,0.001~0.0032 s^(-1),该区域η值高达0.57,且因动态再结晶的充分进行,其中心主变形区无剧烈变形晶粒。
With the development of the damage tolerance design concept for long-life structure parts,high strength and high toughness had gradually become the eternal pursuit of titanium alloy materials for main load-bearing structural parts of aircraft.Because of enoughβ-stabilizing elements could reduce its martensite transformation temperature range to below room temperature,metastableβ-titanium alloy was an ideal choice for high-strength and high-toughness titanium alloys,whose mechanical properties could be effectively improved by reasonable heat treatment system.As a new type of high-strength and high-toughness metastableβtitanium alloy,Ti-45651 alloy had a strength as high as 1350 MPa,and it had many advantages such as few kinds of elements,good performance reproducibility and excellent comprehensive mechanical properties etc.It was expected to replace traditional high-strength and hightoughness titanium alloy materials using as the large load-bearing structural parts such as aircraft landing gear.However,metastableβtitanium alloys were sensitive to deformation temperature and strain rate during high-temperature forging,and it was easy to produce microstructure defects such as cracking,un-uniform microstructure,and low forming accuracy due to inappropriate thermal deformation process parameters.At present,there hadn’t seen any research on the high-temperature deformation behavior of Ti-45651 alloy.Therefore,it was necessary to investigate the hot deformation behavior and construct the hot working map of Ti-45651 alloy.The thermal deformation behavior of Ti-4 Al-5 Mo-6 Cr-5 V-1 Nb alloy was investigated based on the isothermal constant strain rate thermal compression test under the condition of deformation temperature from 700 to 900℃and strain rates from 0.001 to 1.000 s;using Gleeble-3800 thermal simulation test machine.The influence of deformation parameters on mechanical properties of this alloy was analyzed by the true stress-true strain curves.The constitutive equation coupled strain was derived through
作者
周琳
刘运玺
陈玮
付明杰
Zhou Lin;Liu Yunxi;Chen Wei;Fu Mingjie(AVIC Manufacture Technology Institute,Beijing 100024,China;Key Laboratory of Power Beam Processing,Beijing 100024,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2022年第1期27-35,共9页
Chinese Journal of Rare Metals
基金
装备预研领域基金项目(61409230409)资助。
