| Pure zirconium and zirconium alloys have been widely used in the field of engineering precision components for anti-alternating temperature due to their excellent resistance against irradiation damage and corrosion resistance,excellent corrosion resistance and structural stability,which is an ideal material to make active components of space crafts.ZrTiAlV alloys show a zirconium alloy with good mechanical properties,however,because of the high strength,the poor plastic deformation ability caused by the large size of the grain size in the process of melting,and difficulties the for mechanical processing,ZrTiAlV alloy can only make a simple component,which greatly limits its industrial applications.In this paper,the electric field assisted heat treatment combined with the strong deformation of ZrTiAlV alloy with fine grain processing and electric field assisted extrusion forming process is put forward,besides,the basic technological process and technological conditions of the two processes are determined.This paper studies the microstructure evolution law of ZrTiAlV alloy underelectric field assisted heat treatment and electric field assisted extrusion,andthe influence of deformation conditions on the microstructure and properties of the products.The purpose of the studyis refine the microstructure of ZrTiAlV alloy,improve the plastic deformation ability,and improve the mechanical properties of the alloy.The evolution law of phaseand microstructure of ZrTiAlV alloy under different technological conditionswas studied by means of throughthe strong deformation process of forging billet-electric field assisted heat treatment-highpressure torsion-electric field assisted heat treatment.Study on the evolution law of microstructure and phase of forging billet blank after different temperature(600??700? and 800?)electric field assisted heat treatment under the condition of high pressure torsion of different pressure(3GPa~5GPa)and different torsion rotations(1 rotation ~ 2 rotations);Study on the evolution law of microstructure under different temperature(700? and 800?)electric field assisted heat treatment after high pressure torsion.Under the condition of 700?-5GPa-800?,the fine and uniform equiaxed?phase grain structure with a grain size about 120?m was obtained.For the subsequent application of ZrTiAlV alloy products,an extrusion process of electric field assisted was proposed to study the distribution law of deformation behavior,temperature field and stress-strain field of the material under the condition of electric field assisted forming.Under the condition of low temperature of 800?~850? and the flow stress less than 28 MPa,the near-net extrusion forming of 47Zr-45Ti-5Al-3V alloy was achieved.The strength of the edge position was reduced from 1580 MPa to 1185 MPa,while the elongation rate was greatly improved.By using the finite element simulation method,the variation of flow stress with temperature was deduced,the finite element simulation of the positive and negative extrusion products of 47Zr-45Ti-5Al-3V alloy ring was carried out,and the distribution law of temperature field,stress field and strain field was obtained.Study on the breaking mechanism of grain and the generation of dislocations in the process of ZrTi Al V alloy;Analysis of the recrystallization law of the grain in the heating process of the strong deformation materials;Study on grain refinementmechanism of ZrTi Al V alloy during electric field assisted heat treatment and HPT.Through the research of this paper,the grain refinement process of ZrTiAlV alloy with the combination of HPT and electric field assisted heat treatment is preliminarily established,which can effectively refine the grain size of ZrTiAlV alloy,shorten the heat treatment time,improve the plasticity and toughness of the material,ensure the alloy has good comprehensive mechanical properties,and provide the basis for further research and engineering application of ZrTiAlV alloy. |
PDF Full Text Request