Method of making an endoprosthesis containing multi-phase stainless steel
View Patent ↗An endoprosthesis fabricated from multi-phase ferrous steel. Endoprostheses can include a variety of devices such as staples, orthodontic wires, heart valves, filter devices, and stents, many of which devices are diametrically expandable devices. Multi-phase ferrous steels include dual phase steels and transformation induced plasticity steels (TRIP steels).
1. A method of making an endoprosthesis comprising the steps of forming a flat sheet of multiphase stainless steel alloy into a desired shape, forming said desired shape into a tubular form, crimping said tubular form onto a balloon based endovascular delivery system, delivering said desired shape to an area of treatment and expanding said desired shape at the area of treatment, wherein the multiphase stainless steel alloy including austenite and ferrite phases, the multiphase stainless steel alloy comprising iron, chromium, nickel, tungsten, molybdenum, nitrogen, carbon, silicon, and manganese, wherein the multiphase stainless steel alloy consists of iron, 16.0-18.0 wt % chromium, 6.0-8.0 wt % nickel, 0.8-1.2 wt % tungsten, 0.6-0.9 wt % molybdenum, 0.2-0.3 wt % nitrogen, at most 2.0 wt % manganese, at most 0.75 wt % silicon, at most 0.03 wt % carbon, at most 0.03 wt % phosphorus, and at most 0.02 wt % sulfur, wherein the multiphase stainless steel alloy has a volume fraction of ferrite of 5% or lower.
2. A method of making an endoprosthesis comprising the steps of forming a tubular form of multiphase stainless steel alloy into a desired shape, crimping said tubular form onto a balloon based endovascular delivery system, wherein the multiphase stainless steel alloy includes austenite and ferrite phases, wherein the multiphase stainless steel alloy comprising iron, chromium, nickel, tungsten, molybdenum, nitrogen, carbon, silicon, and manganese, wherein the multiphase stainless steel alloy consists of iron, 16.0-18.0 wt % chromium, 6.0-8.0 wt % nickel, 0.8-1.2 wt % tungsten, 0.6-0.9 wt % molybdenum, 0.2-0.3 wt % nitrogen, at most 2.0 wt % manganese, at most 0.75 wt % silicon, at most 0.03 wt % carbon, at most 0.03 wt % phosphorus, and at most 0.02 wt % sulfur, wherein the multiphase stainless steel alloy has a volume fraction of ferrite of 5% or lower.
3. A method of making an endoprosthesis comprising the steps of forming a wire of multiphase stainless steel alloy into a desired tubular shape, crimping said tubular shape onto a balloon based endovascular delivery system, delivering said desired shape to an area of treatment, and expanding said desired shape at the area of treatment, wherein the multiphase stainless steel alloy includes austenite and ferrite phases, wherein the multiphase stainless steel alloy comprises iron, chromium, nickel, tungsten, molybdenum, nitrogen, carbon, silicon, and manganese, wherein the multiphase stainless steel alloy consists of iron, 16.0-18.0 wt % chromium, 6.0-8.0 wt % nickel, 0.8-1.2 wt % tungsten, 0.6-0.9 wt % molybdenum, 0.2-0.3 wt % nitrogen, at most 2.0 wt % manganese, at most 0.75 wt % silicon, at most 0.03 wt % carbon, at most 0.03 wt % phosphorus, and at most 0.02 wt % sulfur, wherein the multiphase stainless steel alloy has a volume fraction of ferrite of 5% or lower.
4. The method of claim 3 further comprising the steps of impacting the formed device with a media to impart compressive residual stresses at the surface of the metal.
5. The method of claim 3 further comprising the step of electropolishing the formed device prior to crimping said tubular form onto a balloon based endovascular delivery system.