Effect of Equal-Channel Angular Pressing on corrosion behavior of magnesium alloy for bioabsorbable stents

Stent is employed to expand the narrowed tubular organ such as blood vessel. The persistent presence of a metallic stent yields several problems like late thrombosis, restenosis and chronic inflammation reactions. Biodegradable magnesium stents have been introduced to solve these problems. However, there is still a huge demand in further research on new alloys and stent designs. Then, as fundamental research for this, effect of microstructure change on mechanical properties and corrosion behavior of Equal-Channel Angular Pressed AZ31B magnesium alloy was investigated. As a result of tensile test at room temperature of ECAPed sample, the tensile strength was 316 MPa, which was slightly improved by about 1.08 times compared to the annealed sample. As a result of the corrosion test, corrosion resistance of the ECAPed sample was lower than the annealed sample. It was suggested that stress relieving annealing (aging) after ECAP is beneficial for improving corrosion resistance due to the reduction of crystal defects, and at the same time, it is a method that can further improve ductility.