| The turbine is essential to hydroelectric power driving device. In the waters more sediment, there is difficult issue to be resolved, that is the erosion problems of turbine blade in water power generation. Ti5553 is a new near-β titanium alloy that exhibits excellent high strength, fracture toughness and hardenability, and it has shown great potentials at many fields, such as aviation and space, ocean, ship automation, energy and so on. The application of Ti alloy is limited in the waters more sediment, as many parts, which is made of Ti5553 alloy has erosion wear problems. So the erosion wear characteristic of Ti5553 alloy is becoming a hotspot in the field of marine field of tribology.Microstructure is a key factor that influences the performance of the Ti5553 alloy, and according to the characteristics of thermal processing of Ti5553 alloy. In order to refine the microstructure and improve the abrasion resistance of Ti5553 alloy in the more sediment waters, the advanced Equal Channel Angular Pressing technology, subsequent solution and aging treatment have be en used to process Ti5553 alloy at β phase. And we obtain some significant original results.Firstly, the particle tracking method of ABAQUS is used to simulate the Equal Channel Angular Pressing process of Ti5553 alloy. And we discuss the influence on the distribution of the stress by extrusion die cone angle, extrusion temperature, extrusion speed and coefficient. Simulation results show that, when the extrusion die cone angle are equal to 90 o, the deformation of the specimen is larger and the distribution of the stress is more even. With the increase of coefficients and extrusion speed, the equivalent strain occurs in advance. Under the extrusion temperature of 850℃, extrusion speed of 25 mm·s-1, lubrication condition well, and extrusion die cone angle are 90 o, the Ti5553 alloy can be obtain good deformation.Secondly, the mechanical properties of T5553 alloy have been tested before and after treatment by the Equal Channel Angular Pressing process. The result show that after T5553 alloy has been treatment by the Equal Channel Angular Pressing process, the yield strength, fracture failure, fracture toughness, and impact toughness are increased by 36%, 66%, 49.4%, and 31.4% respectively.Thirdly, comparing the mass loss of Ti5553 alloy which is treated by Equal Channel Angular Pressing processing with which have not, and evaluating the degree of erosion wear of Ti5553 alloy. We get the following results: under the same erosion conditions, after treated by Equal Channel Angular Pressing processing, the mass loss of Ti5553 alloy is reduced 40%, the surface scratch and impact craters crack are reduced 62%, and the standard deviation of gray value is reduced 32%. Moreover, the surface of the specimen is smoother, and the erosion resistance of Ti5553 is also increased.Fourthly, we observe the surface appearance of Ti5553 alloy after it is extruded through Equal Channel Angular Pressing process at different stages of erosion w ear, and discuss the failure cause and mecha nism of erosion of Ti5553 alloy. The results show that, along with the increase of erosion time, the mechanism of erosion of the erosion material, changes from micro-cutting to impact extrusion deformation, and remain the same. The α phase is the key factor to improve the strength, the toughness, plasticity and the erosion wear resistance of Ti5553 alloy, which is uniformly dispersed in dense b matrix.This is the first time to use high temperature Equal Channel A ngular Pressing processing for Ti5553 alloy, and the impact on microstructure and erosion wear characteristic of Ti5553 alloy by high temperature ECAP has been studied. The results show that the mechanical properties and abrasion resistance of Ti5553 alloy can be improved significantly. |
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