Wear-resistant, corrosion-resistant cobalt-based alloys
View Patent ↗A Co-based alloy comprising 13-16 wt % Cr, 20-30 wt % Mo, 2.2-3.2 wt % Si, and balance Co, with a Cr:Si ratio of between about 4.5 and about 7.5, a Mo:Si ratio of between about 9 and about 15, wear resistance, and corrosion resistance in both oxidizing and reducing acids.
1. A Co-based alloy comprising:
13-16 wt % Cr,
20-30 wt % Mo,
2.2-3.2 wt % Si, and
balance Co;
the alloy having a Cr:Si ratio of between about 4.5 and about 7.5, a Mo:Si ratio of between about 9 and about 15, wear resistance, and resistance to both oxidizing and reducing corrosion.
2. The alloy of claim consisting essentially of
13-16 wt % Cr,
20-30 wt % Mo,
2.2-3.2 wt % Si, and
48-62 wt % Co.
3. The alloy of claim 1 having corrosion resistance in reducing acid H 2 SO 4 characterized by less than about 50 mils/year (1.3 mm/year) thickness loss when tested according to ASTM specification G31-72 in a 10% solution at 102° C.
4. The alloy of claim 1 having corrosion resistance in oxidizing acid HNO 3 characterized by less than about 300 mils/year (7.6 mm/year) thickness loss when tested according to ASTM specification G31-72 in a 65% solution at 66° C.
5. The alloy of claim 1 having corrosion resistance in reducing acid HCl characterized by less than about 4 mils/year (0.1 mm/year) thickness loss when tested according to ASTM specification G31-72 in a 5% solution at 66° C.
6. The alloy of claim 1 having impact strength of at least about 2.0 Joules when evaluated by an un-notched Charpy impact test according to ASTM specification E23-96.
7. The alloy of claim 1 having a metal-to-metal wear resistance characterized by a volume loss of less than about 0.06 cubic millimeters when tested according to ASTM G133-95 at 482 C with alloy cylinders in metal-to-metal wear contact with nitrided 310 stainless steel flat plates.
8. The alloy of claim 2 having corrosion resistance in reducing acid H 2 SO 4 characterized by less than about 50 mils/year (1.3 mm/year) thickness loss when tested according to ASTM specification G31-72 in a 10% solution at 102 C.
9. The alloy of claim 2 having corrosion resistance in oxidizing acid HNO 3 characterized by less than about 300 mils/year (7.6 mm/year) thickness loss when tested according to ASTM specification G31-72 in a 65% solution at 66 C.
10. The alloy of claim 2 having corrosion resistance in reducing acid HCl characterized by less than about 4 mils/year (0.1 mm/year) thickness loss when tested according to ASTM specification G31-72 in a 5% solution at 66 C.
11. The alloy of claim 2 having impact strength of at least about 2.0 Joules when evaluated by an un-notched Charpy impact test according to ASTM specification E23-96.
12. The alloy of claim 1 comprising about 14 wt % Cr.
13. The alloy of claim 1 comprising about 26 wt % Mo.
14. The alloy of claim 1 comprising about 2.6 wt % Si.
15. The alloy of claim 1 having a Cr:Si ratio of about 5.4.
16. The alloy of claim 1 having a Mo:Si ratio of about 10.8.
17. The alloy of claim 1 consisting essentially of
13-16 wt % Cr,
20-30 wt % Mo,
2.2-3.2 wt % Si, and
48-62 wt % Co;
wherein the alloy is Mn-free, Cu-free, and free of all alloying elements having a material effect on metallurgical properties other than Cr, Mo, and Si;
wherein, the alloy has a total trace element content of no more than 2 wt %.
18. The alloy of claim 1 consisting essentially of
13-16 wt % Cr,
20-30 wt % Mo,
2.2-3.2 wt % Si, and
48-62 wt % Co;
wherein the alloy is Mn-free, Cu-free, and free of all alloying elements having a material effect on metallurgical properties other than Cr,Mo, and Si;
wherein the alloy has a total trace element content of no more than 2 wt %;
wherein the alloy has a Cr:Si ratio of between 4.5 and 7.5 and a Mo:Si ratio between 9 and 15.
19. The alloy of claim 18 having corrosion resistance in reducing acid H 2 SO 4 characterized by less than about 50 mile/year (1.3 mm/year) thickness loss when tested according to ASTM specification G31-72 in a 10% solution at 102 C.
20. The alloy of claim 18 having corrosion resistance in oxidizing acid HNO 3 characterized by less than about 300 mile/year (7.6 mm/year) thickness loss when tested according to ASTM specification G31-72 in a 65% solution at 66 C.
21. The alloy of claim 18 having corrosion resistance in reducing acid HCl characterized by less than about 4 mils/year (0.1 mm/year) thickness loss when tested according to ASTM specification G31-72 in a 5% solution at 66 C.
22. The alloy of claim 1 having a microstructure of about 40-55% by volume Laves phase.
23. The alloy of claim 1 having a microstructure of about 40-55% by volume Laves phase and a Laves phase Cr:Si ratio between about 1.04 and about 1.36.
24. The alloy of claim 1 consisting essentially of:
13-16 wt % Cr,
20-30 wt % Mo,
2.2-3.2 wt % Si, and
48-62 wt % Co;
wherein the alloy is Mn-free, Cu-free, and free of all alloying elements having a material effect on metallurgical properties other than Cr, Mo, and Si;
wherein the alloy has a total trace element content of no more than 2 wt %;
wherein the alloy has a Cr:Si ratio of between 4.5 and 7.5 and a Mo:Si ratio between 9 and 15;
wherein the alloy demonstrates corrosion resistance in reducing acid H 2 SO 4 characterized by less than about 50 mils/year (1.3 mm/year) thickness loss when tested according to ASTM specification G31-72 in a 10% solution at 102 C, corrosion resistance in oxidizing acid HNO 3 characterized by less than about 300 mils/year (7.6 mm/year) thickness loss when tested according to ASTM specification G31-72 in a 65% solution at 66 C, and corrosion resistance in reducing acid HCl characterized by less than about 4 mils/year (0.1 mm/year) thickness loss when tested according to ASTM specification G31-72 in a 5% solution at 66 C.
25. The alloy of claim 1 consisting essentially of, by approximate wt %:
14 Cr,
26 Mo,
2.6 Si, and
48-62 wt % Co;
wherein the alloy is Mn-free, Cu-free, and free of all alloying elements having a material effect on metallurgical properties other than Cr, Mo, and Si; and
wherein the alloy has a total trace element content of no more than 2 wt %.
26. A Co-based alloy consisting essentially of:
13-16 wt % Cr,
20-30 wt % Mo,
2.2-3.2 wt % Si, and
48-62 wt % Co;
wherein the alloy is Mn-free; Cu-free; free of all alloying elements having a material effect on metallurgical properties other than Cr, Mo, and Si; and has a total trace element content of no more than about 2 wt %;
wherein the alloy has a Cr:Si ratio of between 4.5 and 7.5 and a Mo:Si ratio between 9 and 15;
wherein the alloy demonstrates corrosion resistance in reducing acid H 2 SO 04 characterized by less than about 50 mils/year (1.3 mm/year) thickness loss when tested according to ASTM specification G31-72 in a 10% solution at 102 C, corrosion resistance in oxidizing acid HNO 3 characterized by less than about 300 mils/year (7.6 mm/year) thickness loss when tested according to ASTM specification G31-72 in a 65% solution at 66 C, corrosion resistance in reducing acid HCl characterized by less than about 4 mils/year (0.1 mm/year) thickness loss when tested according to ASTM specification G31-72 in a 5% solution at 66 C, and impact strength of at least about 2.0 Joules when evaluated by an un-notched Charpy impact test according to ASTM specification E23-96; and
wherein the alloy has a microstructure comprising about 40-55% by volume Laves phase.
27. The alloy of claim 1 being in powder form suitable for deposition by plasma transferred arc welding deposition, laser cladding, plasma spraying, or high velocity oxyfuel spraying.
28. The alloy of claim 1 being in the form of welding rods.
29. The alloy of claim 1 being in the form of wires.
30. The alloy of claim 1 being in the form of electrodes.
31. The alloy of claim 1 being in the form of a casting.
32. The alloy of claim 1 being in the form of powder metallurgical components.