Processing Of Thin Magnesium Tubes By Tubular Channel Angular Pressing (TCAP) Process With Trapezoidal Geometry

Due to the compatibility of Magnesium with the body, it is a suitable material for making biodegradable stents, although its mechanical properties are not desirable for stent application. Accordingly, lately, microstructure and mechanical properties of magnesium have been improved using various methods, including Severe Plastic Deformation (SPD). Many SPD methods have been introduced for the fabrication of ultrafine grain tubes until now, and the process of Tubular Channel Angular Pressing (TCAP) is the most effective one. In this research, by optimally designing the geometrical parameters of the trapezoidal channel, the process force in TCAP has been reduced, and for the first time, magnesium tubes with a thickness of 1 mm have been processed using this process. At the beginning of the research, using the finite element model, the process was simulated in Abaqus software, and the effect of the geometric parameters on the process force was investigated. To investigate the performance of the process with optimal geometric parameters, magnesium tubes with an outer diameter of 5 mm and a thickness of 1 mm were processed at a temperature of 200°C in three passes. The results of metallographic, microhardness, and tensile tests show that the TCAP process with trapezoidal geometry and optimal geometrical parameters is a suitable process for modifying the microstructure and improving the mechanical properties of magnesium tubes with a thickness of one millimeter. The values of yield strength and ultimate strength in the second pass are 1.6 and 1.26 times the initial sample, respectively, and have reached 60 and 92 MPa. The average grain size and hardness have reached from 200 µm and 30 HV in the initial sample to 3 µm and 40 HV after the third pass, respectively. The ductility and strength of processed samples have improved compared to the initial sample.