A method for preparing ultrafine-grained magnesium alloy microtubes for vascular stents

Abstract

The invention discloses a method for preparing ultra-fine grain magnesium alloy microtube for a vascular stent. The method comprises the steps that firstly, an extrusion magnesium alloy blank is subjected to solution treatment at 400DEG C to 470DEG C for 48h-72h; under the condition that the extrusion ratio is 2-4, the preheating temperature of a mould is 300DEG C to 420DEG C, and the extrusion pass is 2-8, the magnesium alloy blank is subjected to reciprocating extrusion processing to obtain an extruded blank with the grain size of 0.3[mu]m-5[mu]m, and then the extruded blank is cut into a phi 20mm*10mm blank; then punching, decontamination and polishing are carried out; and the hot extrusion mould is preheated at 380DEG C to 400DEG C, a lubricant is used for correspondingly lubricating the mould and the blank at an extrusion ratio of 100-200, and forward extrusion is directly carried out on the blank. The microtube prepared by the method has smooth surface, high dimensional accuracy,high straightness, fine and uniform structure and high elongation rate, and the corrosion performance tends to uniform corrosion.

Description

technical field [0001] The invention belongs to the technical field of biodegradable material processing, and in particular relates to a method for preparing ultrafine-grained magnesium alloy microtubes for vascular stents. Background technique [0002] Cardiovascular disease kills about 17 million people every year and is the leading cause of death in the world. According to the report of the World Health Organization, this number will increase to 23.6 million by 2030. Coronary artery disease is the most common type of cardiovascular disease. Implantation of stents is one of the effective treatments for coronary artery disease. At present, the commonly used metal materials for vascular stents in clinic mainly include 316L stainless steel, nickel-titanium materials and cobalt-chromium materials. These metal materials have good mechanical properties, but they are all inert metals. Once implanted, they will remain in the human body permanently as foreign objects. In the long...

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Problems solved by technology

Patent 201310068457.1 uses directional solidification to directly cast pure magnesium tube blanks, and then performs multi-pass cold drawing to prepare finished fine tubes. However, due to the direct casting method, magnesium alloys are prone to segregation, inclusions and other defects, and the uniformity of the tube blanks is difficult. Guarantee; patent 201610306918.8 extrudes the as-cast magnesium alloy micro-tubes after solid solution treatment, but due to the poor performance of the as-cast billets, the success rate of direct extrusion is low, and the length of the pipes is short, so it is difficult to achieve mass production; Document (DOI : 10.1016 / j.msec.2013.04.039) Magnesium alloy fine tubes were prepared by reverse extrusion and drawing with floating mandrel, but the grain size of the tubes was coarse, and there was also the problem that the length of the tubes was not high; the literature (DOI : 10.1016 / j.actbio.2013.01.010) Ultra-fine-grained magnesium alloy microtubes were prepared by equal channel angular extrusion + hot extrusion, and low-temperature hot extrusion (below 200°C) was used to prevent the growth of fine grains , the cylindrical slip system and the conical slip system cannot be activated, resulting in difficulty in hot extrusion and easy cracking

The literature (DOI: 10.1016 / j.jallcom.2017.06.201) used reciprocating expansion + pipe hot extrusion to prepare magnesium alloy micro-tubes, and the grain size of the tubes was 5.5 µm, but there were also problems that the length of the tubes was not enough, and the grain size was not fine and uniform enough. shortcoming

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