Endoprosthesis containing multi-phase ferrous 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 medical device comprising a multiphase stainless steel alloy, wherein the stainless steel alloy comprises iron, chromium, nickel, tungsten, molybdenum, nitrogen, carbon, silicon, and manganese, wherein the multiphase stainless steel alloy has a volume fraction of ferrite comprising 11% or less, and wherein the device comprises an endoprosthesis.
2. The medical device of claim 1 , wherein the stainless steel alloy comprises 16.0-18.0 wt % chromium.
3. The medical device of claim 1 , wherein the stainless steel alloy comprises 6.0-8.0 wt % nickel.
4. The medical device of claim 1 , wherein the stainless steel alloy comprises 0.8-1.2 wt % tungsten.
5. The medical device of claim 1 , wherein the stainless steel alloy comprises 0.6-0.9 wt % molybdenum.
6. The medical device of claim 1 , wherein the stainless steel alloy comprises 0.2-0.3 wt % nitrogen.
7. The medical device of claim 1 , wherein the stainless steel alloy comprises at most 2.0 wt % manganese.
8. The medical device of claim 1 , wherein the stainless steel alloy comprises at most 0.75 wt % silicon.
9. The medical device of claim 1 , wherein the stainless steel alloy comprises at most 0.03 wt % carbon.
10. The medical device of claim 1 , wherein the stainless steel alloy further comprises phosphorus.
11. The medical device of claim 10 , wherein the stainless steel alloy further comprises at most 0.03 wt % phosphorus.
12. The medical device of claim 1 , wherein the stainless steel alloy further comprises sulfur.
13. The medical device of claim 12 , wherein the stainless steel alloy further comprises at most 0.02 wt % sulfur.
14. The medical device of claim 1 , wherein the 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.
15. The medical device of claim 1 , wherein the medical device is MRI-compatible.
16. The medical device of claim 1 , wherein the stainless steel alloy has a volume fraction of ferrite of about 5% or less.
17. The medical device of claim 1 , wherein the stainless steel alloy is annealed, having a strength greater than an annealed 316L stainless steel, lower work hardening than an annealed L605, and elongation between 50-100%.
18. The medical device of claim 1 , wherein the stainless steel alloy is non-magnetic.
19. The medical device of claim 1 , wherein the pitting resistance number of the stainless steel alloy is higher than that of 316L stainless steel.
20. The medical device of claim 19 , wherein the pitting resistance number of the stainless steel alloy is about 25.
21. The medical device of claim 1 , wherein the stainless steel alloy has an elastic recoil less than that of L605.
22. The medical device of claim 1 , wherein the corrosion resistance of the stainless steel alloy is equivalent to that of 316L stainless steel.
23. The medical device of claim 1 , wherein the endoprosthesis comprises a balloon expandable stent.
24. The medical device of claim 23 , further comprising a balloon catheter coupled to the balloon expandable stent.
25. The medical device of claim 24 , wherein the balloon expandable stent is mounted on the balloon catheter.
26. The medical device of claim 24 , wherein the balloon expandable stent is crimped onto the balloon catheter.
27. The medical device of claim 24 , wherein the balloon catheter is positioned along a longitudinal axis of the balloon expandable stent.
28. The medical device of claim 23 , wherein at least a portion of the balloon expandable stent is covered with a polymeric material.
29. The medical device of claim 28 , wherein the polymeric material comprises a fluoropolymer.
30. The medical device of claim 28 , wherein the polymeric material comprises a copolymer of tetrafluoroethylene and a polyalkylvinylether.
31. The medical device of claim 28 , wherein the polymeric material comprises a bioactive substance.
32. The medical device of claim 23 , wherein at least a portion of the balloon expandable stent is coated with a bioactive substance.