Tensile Creep Properties of Ti6321 Alloy with Different Structures at Room Temperature
The creep behavior of equiaxed,duplex and Widmanstatten structures of Ti6321 alloy at room temperature under the tensile stress of 706 MPa for 200 h was studied.The microstructure morphology of the samples after creep was observed by 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,and the new dislocation is(10(1)1)<11(2)3>cross slip;{10(1)0 }<11(2)0>prismatic slip occurs in the primary α phase of duplex structure((1)101)<(1)(1)20>pyramidal slip occurs in the secondary α phase;while in the Widmanstatten structure,(0001)<(2)110>basal slip is more likely to occur than(1011)<10(1)2>pyramidal slip.