Ti-55Al-3.5Cr合金弯管浇注过程模拟及其组织和力学性能

Pouring Process Simulation of Ti-55Al-3.5Cr Alloy Elbow Pipe and Its Microstructure and Mechanical Properties

对添加TiB2与Ni的Ti-55Al-3.5Cr-2.5Nb-1.5Ni-0.5B合金弯管结构的浇注过程进行有限元仿真分析,并以仿真优化参数制备试样进行组织分析和力学性能测试。结果表明,弯管件充型时,金属液以底座→环形通道→弯管→所有通道的顺序实现管壁的充型,在弯管端部形成了沿内孔分布的缩孔,在底座与内孔附近区域存在缩孔。试生产结果表明,合金中形成了等轴状的片层组织、块状γ相、τ3相以及部分弯曲状的硼化物,在片层组织中还存在部分B2相。室温下合金的屈服强度、抗拉强度、伸长率分别为569MPa、612MPa、0.57%,试样断口平齐,表现为脆性解理断裂。

The casting process of Ti-55Al-3.5Cr-2.5Nb-1.5Ni-0.5 Balloy elbow pipe was simulated by finite element method,and microstructure and mechanical properties of the samples were analyzed.The results show that during filling process,the liquid metal first reaches the base to complete the filling process,and then flows into the bending pipe along the annular channel of the bending pipe,and then extends to all the channels to realize the filling process of the pipe wall.Ring shrinkage holes were formed at the end of the bend along the inner hole,and some shrinkage holes were found near the base and inner hole.Many equiaxial lamellar structures,the lumpγphase,theτ3 phase and part of curved boride can be observed in the alloy,and part of B2 phase structure is formed in the lamellar structure.The alloy has excellent tensile properties,such as 569 MPa in yield strength,612 MPa in tensile strength and 0.57%in elongation.The tensile fracture formed at room temperature has obvious brittle cleavage fracture characteristics with smooth fracture morphology.