TA2钛合金管材热态气压胀形性能及力学性能

摘要

通过单向拉伸试验测试TA2钛合金管材在700～850℃和4×10-4 S-1～4×10-1 S-1应变速率下的力学性能,观察拉伸断口形貌.开发管材热态胀形实验装置,测试管材在770～950℃的热态气压胀形性能,获得胀破压力和极限胀形率随温度的变化规律,并对典型的破裂形式进行分析.结果表明:TA2钛合金管材的抗拉强度随着温度的升高或应变速率的减小而减小；总伸长率显著增大(142％～331％).热态气压胀形时,随着温度的升高,胀破压力从6.5 MPa单调下降至1.2 MPa,极限胀形率呈先增加后降低的变化趋势,在890℃时达到最大值,约70％.在不同温度下气胀时,出现环向破裂、轴向破裂及分散破裂3种不同的破裂形式.TA2钛合金管材适合的热态气压成形温度区间为860～920℃.%The mechanical properties of TA2 extruded tube were tested by uniaxial tensile test at high temperatures ranging from 700 ℃ to 850 ℃ and different strain rates changing from 4×10-4 s-1 to 4x 10-1 s-1.The tube bulging test was carried out at elevated temperatures up to 950 ℃ to evaluate the formability of TA2 extruded tube for hot metal gas forming (HMGF).The total elongation and the maximum expansion ratio of the tube were obtained.The bursting pressure and fracturing manner were analyzed.The results show that the tensile strength of TA2 tube decreases practically with temperature increasing and strain rate decreasing.Meanwhile,the total elongation is between 142％ and 331％.In tube bulging test,special experimental setup was established by the way of induction heating.The bursting pressure decreases from 6.5 MPa to 1.2 MPa as temperature increases.The maximum expansion ratio increases firstly and reaches the maximum value of about 70％ at 890 ℃,and then decreases.Fracture occurs along hoop direction,axial direction and random direction at different temperatures.The ideal temperature range for TA2 tube forming is from 860 ℃ to 920 ℃ in HMGF process.