BT25y钛合金热稳定性能研究

Influence of Long-Term Thermal Exposure on Properties of BT25y Alloy

通过力学性能测试、X射线衍射仪、透射电镜和扫描电镜等方法,研究了BT25y钛合金的热稳定性能。结果表明,BT25y合金的抗拉强度与屈服强度随固溶温度的变化曲线表现出马氏体型钛合金的特征;合金固溶时效后,在500和550℃经300～2000h热暴露后抗拉强度Rm为1380～1420MPa,均在高强度状态下,还有较好的塑性,表明在500和550℃合金组织是热稳定的;断口形貌清楚表明,纤维区、放射区及剪切唇的断口特征十分明显,纤维区、裂纹核心源区和放射扩展区均为韧窝深的韧性断裂断口形貌,而剪切撕裂区也为韧性断裂断口形貌,只是韧窝深浅程度有变化,随热稳定时间的延长,韧窝逐渐变浅,同时还发现了二次裂纹;在500和550℃热暴露过程中发生了α→α+α2的相转变,且α相和α2相共存。

Thermal stability of BT25y titanium alloy was studied by means of mechanical property testing, X-ray diffraction transmission electron microscope and scanning electron microscope. The results showed that the curve of tensile strength and yield strength vs. solution treatment temperature was characterized by martensite type titanium alloy features. After solution treatment and thermal exposure at 500 and 550 ℃ for 300- 2000 h, good tensile strength, ranging from 1380 to 1420 MPa, was coupled with nice plasticity. So the alloy is thermal stable exposure at the above temperature range for 300 - 2000 h. Ductile rupture features could be found in fracture profile. As exposure time went on, secondary crack could also be found, α and α2, which were caused by the phase transformation α→α ＋α2 during the thermal exposure at 500 and 550 ℃, were coexisting.