Powder made of a cobalt-chromium alloy

Abstract

A titanium-free cobalt-chromium alloy for a powder, contains (in wt. %) C 0.40-1.50%, Cr 24.0-32.0%, W 3.0-8.0%, Mo 0.1-5.0%, where 4.0<W+Mo<9.5 is satisfied by the content of W and Mo in wt. %, Nb max. 0.5%, Ta max. 0.5%, where Nb+Ta<0.8 is satisfied by the content of Nb and Ta in wt. %, Ni 0.005-25.0%, Fe 0.005-15.0%, where Ni+Fe>3.0 is satisfied by the content of Ni and Fe in wt. %, Mn 0.005-5.0%, Al max. 0.5%, N 0.0005-0.15%, Si<0.3%, Cu max. 0.4%, O 0.0001-0.1%, P max. 0.015%, B max. 0.015%, S max. 0.015%, residual Co, and impurities resulting from the production process, in particular Zr max. 0.03% and Ti max. 0.025%.

Claims

1. A method for manufacture of a powder from a titanium-free cobalt-chromium alloy, wherein the alloy comprises (in wt-%) C 0.40-1.50% Cr 24.0-32.0% W 3.0-8.0% Mo 0.1-5.0%, wherein 4.0W+Mo9.5, with the contents of W and Mo in wt-%, is satisfied Nb max. 0.5% Ta max. 0.5%, wherein Nb+Ta0.8, with the contents of Nb and Ta in wt-%, is satisfied Ni 5-21.0% Fe 0.005-15.0%, wherein Ni+Fe>3.0, with the contents of Ni and Fe in wt-%, is satisfied Mn 0.005-5.0% Al max. 0.5% N 0.0005-0.03% Si<0.3% Cu max. 0.4% O 0.0001-0.1% P max. 0.015% B max. 0.015% S max. 0.015% Co the rest and manufacturing-related impurities, especially Zr max. 0.03% Ti max. 0.025%, wherein the powder is produced in a vacuum inert-gas atomization system (VIGA), and in the vacuum inert-gas atomization system, the alloy is smelted in a vacuum induction smelting furnace to form a molten melt and the molten melt is held for 20 minutes to 2 hours for homogenization and passed into a casting gate, which leads to a gas stream having a gas flow rate of 2 to 150 m.sup.3/min, in which molten metal of the molten melt is atomized at a metal flow rate during atomization of 0.5 to 80 kg/min to metal particles under pressure of 5 to 100 bar with inert gas, the molten melt being heated in a melting crucible at 5 to 400 C. above melting point and due to rapid cooling, the metal particles solidify in a form of spherical particles, and a gas phase is then separated from the powder in a cyclone, after which the powder is packaged.

2. The method according to claim 1, further comprising using the powder in a generative fabrication method and/or in combination with a hot isostatic pressing (HIP) method, or using the powder for build-up welding and/or coating.

3. The method according to claim 1, further comprising using the powder for generation of a component part and/or a coating under tribological, corrosive or oxidizing conditions or combinations of such conditions.

Description

(1) In Table 3, first exemplary atomized chemical compositions are presented (akin to B-12 and B-13 with different Ni contents). It is possible, by means of laser-based additive fabrication, to generate component parts having different process parameters without macro-cracks (see FIG. 1).

(2) FIG. 1 shows a material body, built up by means of laser-based additive fabrication, having different process parameters {light-exposure strategies) without macro-cracks.

(3) As predicted in the thermodynamic calculations, no primary M.sub.7C.sub.3 carbides as well as eutectic solidification were detected. The carbide precipitation of M.sub.23C.sub.6 is induced by means of heat treatment. Advantages of this are that carbide size and distribution may be controlled by a heat treatment.

(4) TABLE-US-00003 TABLE 3 First exemplary atomized chemical compositions. P10331 P10332 P10333 P10376 P10377 E E E E E C 0.78 0.77 0.80 0.82 0.80 Cr 26.92 28.97 28.62 28.34 27.64 W 4.01 4.07 4.28 4.19 4.22 Mo 1.48 1.43 1.45 1.56 1.44 Fe 0.05 0.04 0.05 0.08 0.08 Ni 10.06 9.91 9.92 18.68 20.11 Mn 0.001 0.001 0.012 n.a. n.a. Al 0.015 0.013 0.015 n.a. n.a. Si 0.01 0.01 0.03 0.02 0.02 Ti 0.001 0.001 0.001 n.a n.a. Nb 0.001 0.002 0.001 0.01 0.01 N 0.002 0.002 0.002 0.002 0.002 B 0.0005 0.0005 0.0005 0.001 0.001 Zr 0.001 0.001 0.001 O 0.010 0.011 0.011 0.009 0.009 Andere n.a. n.a. n.a. n.a. n.a. Co Rest Rest Rest Rest Rest n.a. = not analyzed. Andere = Others; Rest = the rest