Ti6Al4V钛合金冷轧板材的超塑性变形行为研究  

Research on Superplastic Deformation Behavior of Ti6Al4V Titanium Alloy Cold-rolled Sheet

作　　者：徐勇[1,2] 杨湘杰[1] 杜丹妮[1] XU Yong;YANG Xiangjie;DU Danni(School of Mechatronics Engineering,Nanchang University,Nanchang 330031,China;School of Materials Science and Engineering,Nanchang Hangkong University,Nanchang 330063,China)

机构地区：[1]南昌大学机电工程学院,江西南昌330031 [2]南昌航空大学材料科学与工程学院,江西南昌330063

出　　处：《热加工工艺》2018年第24期38-42,共5页Hot Working Technology

基　　金：国家自然科学基金资助项目(51164029);江西省科技重点研发计划资助项目(20151BBE50042)

摘　　要：在温度830～890℃和应变速率0.0005～0.005 s^(-1)下对Ti6Al4V钛合金冷轧板材进行超塑性拉伸实验。利用光学显微镜和扫描电镜观察变形后的微观组织和断口形貌。研究了该合金的超塑性变形行为和变形机理。结果表明:在应变速率为0.0005、0.005 s^(-1)时,随着变形温度的升高,伸长率先升高后降低;在应变速率为0.001 s^(-1)时,随着变形温度的升高,伸长率逐渐降低;在830℃和0.001 s^(-1)条件下伸长率达到最大值1259.0%;超塑性最优变形参数区间为温度830～850℃、应变速率0.0005～0.001 s^(-1)。合金的应变速率敏感性指数m值随温度升高先增加,850℃时达到最大值0.472,随后逐渐减小;超塑性变形下的平均激活能为259 k J/mol。超塑性变形过程发生了明显的动态再结晶,微观组织完全转变为等轴组织。超塑性变形的主要机制为晶界滑移。Ti6Al4V合金板材超塑性拉伸断裂属为于沿晶断裂。The superplastic tensile tests were carried out for Ti6Al4V titanium alloy cold-rolled sheet at 830-890℃ and strain rate of 0.0005-0.005 s^-1.The microstructure and the morphology of the fracture after deformation were examined by optical microscopy and SEM.The superplastic deformation behaviour and deformation mechanism of the alloy were investigated.The tensile results indicate that the elongation first increases and then decreases with the increase of deformation temperature at strain rate of 0.0005 s^-1and 0.05 s^-1 and,at the strain rate of 0.001 s^-1,the elongation gradually decreases with the deformation temperature increasing.The maximum elongation of 1259.0%appears at 830℃with the strain rate of 0.001s^-1.The optical domain of superplastic deformation is temperature of 830-850℃and strain rate of 0.0005-0.001 s^-1.The strain rate sensitivity value m of the alloy increases with the deformation temperature increasing,and at the maximum m-value(0.472)appears 850℃,and then decreases gradually.The average activation energy under superplastic deformation is 259kJ/mol.The obvious dynamic recrystallization(DRX)occur in superplastic deformation,the microstructure completely transforms into equiaxed microstructure.The grain boundary sliding is the dominant deformation mechanism during the superplastic deformation.The superplastic tensile fracture of Ti6Al4V titanium alloy sheet is intergranular fracture.

关 键 词：TI6AL4V钛合金 超塑性 变形行为 变形机制 

分 类 号：TG146.23[一般工业技术—材料科学与工程]