Ti6321合金不同组织室温拉伸蠕变行为研究

Tensile creep properties of Ti6321 alloy with different structures at room temperature

摘要:

作者研究了Ti6321合金等轴、双态和魏氏组织室温下706MPa拉伸应力作用200h的蠕变行为，采用透射电子显微镜（TEM）观察了Ti6321合金不同组织拉伸蠕变后的微观组织形貌，并通过迹线法分析了位错滑移类型。结果表明：Ti6321合金等轴组织的蠕变应变最大，双态组织次之，魏氏组织最小。通过对蠕变曲线进行一阶求导，找到蠕变速率变化转折点，得到不同阶段的蠕变应变，发现初始蠕变应变大小与组织中残留的位错量成正相关。Ti6321合金室温蠕变机制主要是位错滑移，拉伸蠕变过程中等轴组织发生了原始胞状位错分解和新位错滑移的形成，该位错为(10-11)<11-23>交滑移；双态组织初始α相发生了{10-10}<11-20>柱面滑移，次生α相发生了 (-1101)<-1-120>锥面滑移；魏氏组织发生了(0001)<-2110>基面滑移，可能发生了(10-11)<10-12>锥面滑移。

Abstract:

The creep behavior of equiaxed, duplex and widmanstatten structures of Ti6321 alloy under tensile stress of 706MPa for 200h was studied. The microstructure morphology of the samples after creep was observed by metallographic microscope and transmission electron microscope (TEM), and the dislocation slip types of different microstructures of Ti6321 alloy were analyzed by trace method. The results show that the creep strain of equiaxed structure of Ti6321 alloy is the largest, followed by duplex structure and widmanstatten structure. Through the first derivative of creep curve, the turning point of creep rate change was found, and the creep strain of different stages was obtained. It is found that the primary creep strain is positively related to the amount of residual dislocation in the structure. The creep mechanism of Ti6321 alloy at room temperature is mainly dislocation slip, the original cellular dislocation decomposes and the new dislocation slip forms during the tensile process of equiaxed structure, the new dislocation is (10-11)<11-23> cross slip; the primary α phase of duplex structure mainly occurs {10-10}<11-20> prismatic slip, the secondary α phase occurs (-1101)<-2110> pyramidal slip; widmanstatten structure starts (0001)<-2110> basal slip and (10-11)<10-12> pyramidal slip.