Numerical Simulation And Experimental Study On A New Technics Named As Equal Channel Angular Extrusion And Twist

With the development of materials science, severe plastic deformation method(SPD) has become a well-established method for manufacturing Ultrafine-grained materials. As two basic methods, equal channel angular extrusion (ECAE) and twist extrusion (TE) have many common advantages in the field of manufacturing Ultrafine-grained materials, but both of them have the same fatally flawed that the refining capacity is not enough. So, exploring new and efficient severe plastic deformation method for manufacturing Ultrafine-grained materials has a great significance.Based on the principle of the two methods mentioned, equal channel angular extrusion and twist (ECAE-T) was proposed as a new SPD method in this paper. The essence of ECAE-T is that the channel of ECAE-T is appended a TE channel after the channel of ECAE in order to increase the effective strain of one pass ECAE-T by enhance the hydrostatic pressure at the corner, by which the ECAE-T can refine crystalline grain with improving the organizational structure. The exploration and study about this process is still the first time at home and abroadIn this paper, finite element simulation analysis about ECAE-T with pure aluminum was carried out by Deform-3D, the deformation characteristics and stress strain distribution was obtained, and the load variation was obtained too. The factors which affect the ECAE-T deformation such as the geometric shapes factors (the helix angleβ, TE angleγand transition distance L1 (distance between ECAE channel and TE channel)) and the process parameters (contact friction condition m, deformation temperature t, deformation velocity v, etc.) were systemic investigated. The effect to ECAE-T deformation behavior and the distribution of the stress,strain,load and so on of all the parameters were comprehensively studied, which can supply a theoretical basis for us to optimize the process parameters and die design.With the results of simulation analysis, based on laboratory-based 200T pressure torsion machine equipment, using two-story structure of steel and concrete composite die, the ECAE-T mold was designed and manufactured for the first time and was verified by experiment. The experiment showed that the mold is reasonable, adequate strength, and that the simulation results and experimental results were consistent. In order to study the ECAE-T deformation fully and analysis its relative advantages of ECAE, experiments about pure aluminum were done. At the help of experiments, the features of that ECAE-T has stronger deformation and better ability to refine grain was known. Then more ECAE-T experiments at different pass (such as 1, 2, 3 and 4 pass) were carried out to investigate the microstructure evolution, tensile experiments were carried out to study the change mechanical properties, and the revolution of the microstructure was preliminarily analyzed. These experimental results makes the most direct validation for simulation study, the research in this paper provides the experimental material for the analysis of ECAE-T deformation mechanism.