Hypereutectic white iron alloys comprising chromium, boron and nitrogen and articles made therefrom
09580777 ยท 2017-02-28
Inventors
Cpc classification
International classification
Abstract
Disclosed are a hypereutectic white iron alloy and articles such as pump components made therefrom. Besides iron and unavoidable impurities the alloy comprises, in weight percent based on the total weight of the alloy, from 3 to 6 C, from 0.01 to 1.2 N, from 0.1 to 4 B, from 3 to 48 Cr, from 0.1 to 7.5 Ni and from 0.1 to 4 Si and, optionally, one or more of Mn, Co, Cu, Mo, W, V, Mg, Ca, rare earth elements, Nb, Ta, Ti, Zr, Hf, Al.
Claims
1. A hypereutectic white iron alloy, wherein the alloy comprises, in weight percent based on a total weight of the alloy: TABLE-US-00010 C from 3 to 6 B from 0.1 to 4 N from 0.01 to 1.2 Cr from 3 to 48 Ni from 0.1 to 7.5 Si from 0.1 to 4 Mn from 0 to 8 Co from 0 to 5 Cu from 0 to 5 Mo from 0 to 5 W from 0 to 6 V from 0 to 12 Nb from 0 to 6 Ti from 0 to 5 Zr from 0 to 2 (Mg + Ca) from 0 to 0.2 one or more rare earth elements from 0 to 3 one or more of Ta, Hf, Al from 0 to 3, remainder Fe and incidential impurities; and wherein the alloy in an as cast state has a Brinell hardness (HB) of at least 700.
2. The alloy of claim 1, wherein the alloy has a carbide-boride-nitride volume fraction (CBNVF) of at least 50, calculated according to the following equation:
CBNVF=C.sub.E12.33+(% Cr+% M)0.5515.2 with M=total percentage of V, Mo, Nb, and Ti, and C.sub.E=% C+% N+(f% B), where f=1.2 for B concentrations from 0.1% to 0.49% 1.48 for B concentrations from 0.5% to 0.99% 2.2 for B concentrations from 1.0% to 1.8% 2.6 for B concentrations from 1.81% to 2.5% 2.7 for B concentrations from 2.51% to 3.0% 2.8 for B concentrations from 3.01% to 4%.
3. The alloy of claim 2, wherein the alloy has a CBNVF of at least 55.
4. The alloy of claim 2, wherein the alloy has a CBNVF of at least 60.
5. The alloy of claim 1, wherein the alloy comprises TABLE-US-00011 C from 3 to 4.8 B from 0.5 to 4 N from 0.01 to 0.1 Cr from 3 to 11 Ni from 4 to 7.5 Si from 1.6 to 2.8 Mn from 0.1 to 3 Mo from 0 to 1 W from 0 to 2 V from 0 to 4 Nb from 0 to 2 Ti from 0 to 3 Zr from 0 to 2 Al from 0.1 to 2.
6. The alloy of claim 1, wherein the alloy comprises TABLE-US-00012 C from 3.5 to 4.5 B from 0.6 to 3.5 N from 0.01 to 0.2 Cr from 12 to 23 Ni from 0.1 to 4 Si from 1.6 to 2.8 Mn from 0.1 to 5 Mo from 0 to 3 W from 0 to 2 V from 0 to 5 Nb from 0 to 2 Ti from 0 to 3 Zr from 0 to 2 Al from 0.01 to 1.5.
7. The alloy of claim 6, wherein the alloy comprises from 1.5% to 4% of Ni.
8. The alloy of claim 6, wherein the alloy has a carbide-boride-nitride volume fraction (CBNVF) of at least 60, calculated according to the following equation:
CBNVF=C.sub.E12.33+(% Cr+% M)0.5515.2 with M=total percentage of V, Mo, Nb, and Ti, and C.sub.E=% C+% N+(f% B), where f=1.48 for B concentrations from 0.5% to 0.99% 2.2 for B concentrations from 1.0% to 1.8% 2.6 for B concentrations from 1.81% to 2.5% 2.7 for B concentrations from 2.51% to 3.0% 2.8 for B concentrations from 3.01% to 4%.
9. The alloy of claim 1, wherein the alloy comprises TABLE-US-00013 C from 3.5 to 4.5 B from 0.6 to 3.5 N from 0.01 to 0.3 Cr from 24 to 30 Ni from 0.1 to 3.5 Si from 1.6 to 2.8 Mn from 0.1 to 6 Mo from 0 to 3 W from 0 to 2 V from 0 to 5 Nb from 0 to 2 Ti from 0 to 3 Zr from 0 to 2 Al from 0.01 to 1.5.
10. The alloy of claim 9, wherein the alloy comprises from 1.5% to 3.5% of Ni.
11. The alloy of claim 9, wherein the alloy comprises from 3% to 6% of Mn.
12. The alloy of claim 9, wherein the alloy has a carbide-boride-nitride volume fraction (CBNVF) of at least 65, calculated according to the following equation:
CBNVF=C.sub.E12.33+(% Cr+% M)0.5515.2 with M=total percentage of V, Mo, Nb, and Ti, and C.sub.E=% C+% N+(f% B), where f=1.48 for B concentrations from 0.5% to 0.99% 2.2 for B concentrations from 1.0% to 1.8% 2.6 for B concentrations from 1.81% to 2.5% 2.7 for B concentrations from 2.51% to 3.0% 2.8 for B concentrations from 3.01% to 4%.
13. The alloy of claim 1, wherein the alloy comprises TABLE-US-00014 C from 3.5 to 6 B from 0.6 to 3.5 N from 0.01 to 1.2 Cr from 31 to 48 Ni from 0.1 to 3.5 Si from 1.6 to 3.5 Mn from 0.1 to 8 Mo from 0 to 3 W from 0 to 2 V from 0 to 5 Nb from 0 to 2 Ti from 0 to 3 Zr from 0 to 2 Al from 0.01 to 1.5.
14. The alloy of claim 13, wherein the alloy has a carbide-boride-nitride volume fraction (CBNVF) of at least 65, calculated according to the following equation:
CBNVF=C.sub.E12.33+(% Cr+% M)0.5515.2 with M=total percentage of V, Mo, Nb, and Ti, and C.sub.E=% C+% N+(f% B), where f=1.48 for B concentrations from 0.5% to 0.99% 2.2 for B concentrations from 1.0% to 1.8% 2.6 for B concentrations from 1.81% to 2.5% 2.7 for B concentrations from 2.51% to 3.0% 2.8 for B concentrations from 3.01% to 4%.
15. The alloy of claim 1, wherein the alloy in an as cast state has a Brinell hardness (HB) of at least 720.
16. The alloy of claim 1, wherein the alloy in an as cast state has a Brinell hardness (HB) of at least 740.
17. The alloy of claim 1, wherein the alloy in an as cast state has a Brinell hardness (HB) of at least 760.
18. The alloy of claim 1, wherein the alloy in an as cast state has a Brinell hardness (HB) of at least 780.
19. A hypereutectic white iron alloy, wherein the alloy comprises, in weight percent based on a total weight of the alloy: TABLE-US-00015 C from 3 to 4.8 B from 0.5 to 4 N from 0.01 to 0.1 Cr from 7 to 11 Ni from 4 to 7.5 Si from 1.6 to 2.8 Mn from 0.1 to 3 Co from 0 to 5 Cu from 0 to 5 Mo from 0 to 1 W from 0 to 2 V from 0 to 4 Nb from 0 to 2 Ti from 0 to 3 Zr from 0 to 2 (Mg + Ca) from 0 to 0.2 Al from 0.1 to 2 one or more rare earth elements from 0 to 3 one or more of Ta, Hf, Al from 0.1 to 3, remainder Fe and incidential impurities.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The present invention is further described in the detailed description which follows, in reference to the drawings wherein:
(2)
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DETAILED DESCRIPTION OF THE PRESENT INVENTION
(5) The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.
(6) As used herein, the singular forms a, an, and the include the plural reference unless the context clearly dictates otherwise. For example, reference to an alloy would also mean that combinations of two or more alloys can be present unless specifically excluded.
(7) Except where otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, etc. used in the instant specification and appended claims are to be understood as being modified in all instances by the term about. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, each numerical parameter should be construed in light of the number of significant digits and ordinary rounding conventions.
(8) Additionally, the disclosure of numerical ranges within this specification is considered to be a disclosure of all numerical values and ranges within that range. For example, if a range is from 1 to 50, it is deemed to include, for example, 1, 7, 34, 46.1, 23.7, or any other value or range within the range.
(9) The various embodiments disclosed herein can be used separately and in various combinations unless specifically stated to the contrary.
(10) The present invention provides a hypereutectic high chromium white iron alloy wherein a considerable portion of the carbon is replaced by nitrogen and boron. This substitution of carbon by nitrogen and in particular, boron beneficially causes a narrowing of the hypereutectic solidification temperature area and brings the solidification temperature closer to, or even renders it equal to, eutectic solidification temperatures, thereby narrowing the alloy liquidus temperaturesolidus temperature interval. This causes a refinement of primary and eutectic phases of the cast high chromium alloy. The addition of boron and nitrogen further results in a considerable increase of the hardness of the alloy in the as cast state (i.e., without any subsequent hardening treatment).
(11) Without wishing to be bound by any theory, it is believed that the substitution of carbon by boron and nitrogen causes a change of the morphology of the carbides M.sub.7C.sub.3 (with M=Cr, V, Ti, Nb, Al, Mo, W, etc.) into carbon-boron nitrides M.sub.7(C,B,N).sub.3, M.sub.3(C,B,N) and M.sub.23(C,B,N).sub.6. These carbon-boron nitrides optimize the refinement in terms of size and homogeneous distribution in the cast microstructure and substantially increase the carbide-boride-nitride volume fraction (CBNVF).
(12) In addition to iron, the alloy of the present invention comprises six required components, i.e., C, B, N, Cr, Si and Ni. The weight percentage of Cr in the alloy is at least 3%, but not higher than 48%. in the embodiments (i) set forth above the weight percentage of Cr usually is at least 3%, e.g., at least 4%, at least 5%, at least 6%, at least 7%, at least 7.5%, or at least 8%, but not higher than 11%, e.g., not higher than 10.5%, or not higher than 10%. In the embodiments (ii) set forth above the weight percentage of Cr usually is at least 12%, e.g., at least 13%, at least 14%, or at least 15%, but not higher than 23%, e.g., not higher than 22%, not higher than 21%, not higher than 20%, not higher than 19%, not higher than 18%, or not higher than 17%. In the embodiments (iii) set forth above the weight percentage of Cr usually is at least 24%, e.g., at least 25%, at least 26%, or at least 27%, but not higher than 30%, e.g., not higher than 29.5%, or not higher than 29%. In the embodiments (iv) set forth above the weight percentage of Cr usually is at least 31%, e.g., at least 32%, at least 33%, at least 34%, at least 35%, at least 36%, or at least 37%, but not higher than 48%, e.g., not higher than 46%, not higher than 44%, not higher than 42%, not higher than 41%, or not higher than 40%.
(13) The weight percentage of C in the alloy of the present invention is at least 3%, e.g., at least 3.1%, at least 3.2%, at least 3.3%, at least 3.4%, at least 3.5%, at least 3.6%, at least 3.7%, or at least 3.8%, but not higher than 6%, e.g., not higher than 5.5%, not higher than 5%, not higher than 4.8%, or not higher than 4.5%. In the embodiments (i) set forth above, the weight percentage of C usually is at least 3%, e.g., at least 3.1%, at least 3.2%, at least 3.3%, at least 3.4%, at least 3.5%, at least 3.6%, at least 3.7%, or at least 3.8%, but not higher than 4.8%, e.g., not higher than 4.7%, not higher than 4.6%, not higher than 4.5%, not higher than 4.4%, not higher than 4.3%, not higher than 4.2%, or not higher than 4.1%. In the embodiments (ii) set forth above the weight percentage of C usually is at least 3.5%, e.g., at least 3.6%, at least 3.7%, or at least 3.8%, but not higher than 4.5%, e.g., not higher than 4.4%, not higher than 4.3%, not higher than 4.2%, or not higher than 4.1%. In the embodiments (iii) set forth above the weight percentage of C usually is at least 3.5%, e.g., at least 3.6%, at least 3.7%, or at least 3.8%, but not higher than 4.5%, e.g., not higher than 4.4%, not higher than 4.3%, not higher than 4.2%, or not higher than 4.1%. In the embodiments (iv) set forth above the weight percentage of C usually is at least 3.5%, e.g., at least 3.6%, at least 3.7%, at least 3.8%, at least 3.9%, or at least 4%, but not higher than 6%, e.g., e.g., not higher than 5.5%, not higher than 5%, not higher than 4.8%, or not higher than 4.6%.
(14) The weight percentage of N in the alloy of the present invention is at least 0.01%, e.g., at least 0.02%, at least 0.03%, at least 0.04%, at least 0.05%, at least 0.06%, at least 0.07%, at least 0.08%, at least 0.09%, at least 0.1%, at least 0.15%, at least 0.2%, at least 0.25%, at least 0.3%, at least 0.35%, or at least 0.4%, but not higher than 1.2%, e.g., not higher than 1.1%, not higher than 1%, not higher than 0.9%, or not higher than 0.8%. In the embodiments (i) set forth above the weight percentage of N usually is at least 0.01%, e.g., at least 0.015%, at least 0.02%, or at least 0.03%, but not higher than 0.1%, e.g., not higher than 0.09%, not higher than 0.08%, or not higher than 0.07%. In the embodiments (ii) set forth above the weight percentage of N usually is at least 0.01%, e.g., at least 0.015%, at least 0.02%, at least 0.03%, at least 0.04%, or at least 0.05%, but not higher than 0.2%, e.g., not higher than 0.18%, not higher than 0.15%, or not higher than 0.12%, or not higher than 0.1%. In the embodiments (iii) set forth above the weight percentage of N usually is at least 0.01%, e.g., at least 0.015%, at least 0.02%, at least 0.03%, at least 0.04%, at least 0.05%, at least 0.06%, at least 0.08%, or at least 0.1%, but not higher than 0.3%, e.g., not higher than 0.25%, not higher than 0.2%, not higher than 0.18%, or not higher than 0.15%. In the embodiments (iv) set forth above the weight percentage of N usually is at least 0.01%, e.g., at least 0.015%, at least 0.02%, at least 0.03%, at least 0.04%, at least 0.05%, at least 0.06%, at least 0.08%, or at least 0.1%, but not higher than 1.2%, e.g., not higher than 1.1%, not higher than 1%, not higher than 0.9%, or not higher than 0.8%.
(15) The weight percentage of B in the alloy of the present invention is at least 0.1%, e.g., at least 0.15%, at least 0.2%, at least 0.25%, at least 0.3%, at least 0.35%, at least 0.4%, at least 0.45%, at least 0.5%, at least 0.6%, at least 0.7%, at least 0.8%, at least 0.9%, or at least 1%, but not higher than 4%, e.g., not higher than 3.9%, not higher than 3.8%, not higher than 3.7%, not higher than 3.6%, not higher than 3.5%, not higher than 3.4%, not higher than 3.3%, not higher than 3.2%, not higher than 3.1%, not higher than 3%, not higher than 2.9%, not higher than 2.8%, not higher than 2.7%, not higher than 2.6%, not higher than 2.5%, not higher than 2.4%, not higher than 2.3%, not higher than 2.2%, not higher than 2.1%, not higher than 2%, not higher than 1.9% or not higher than 1.8%. In the embodiments (i) set forth above the weight percentage of B usually is at least 0.5%, e.g., at least 0.6%, at least 0.7%, or at least 0.8%, but not higher than 4%, e.g., not higher than 3.9%, not higher than 3.8%, not higher than 3.7%, not higher than 3.6%, not higher than 3.5%, not higher than 3.4%, not higher than 3.3%, not higher than 3.2%, not higher than 3.1%, not higher than 3%, not higher than 2.9%, not higher than 2.8%, not higher than 2.7%, not higher than 2.6%, not higher than 2.5%, not higher than 2.4%, not higher than 2.3%, not higher than 2.2%, not higher than 2.1%, not higher than 2%, not higher than 1.9% or not higher than 1.8%. In the embodiments (ii), (iii) and (iv) set forth above the weight percentage of B usually is at least 0.6%, e.g., at least 0.65%, at least 0.7%, at least 0.75%, at least 0.8%, at least 0.85%, or at least 0.9%, but not higher than 3.5%, e.g., not higher than 3.4%, not higher than 3.3%, not higher than 3.2%, not higher than 3.1%, not higher than 3%, not higher than 2.9%, not higher than 2.8%, not higher than 2.7%, not higher than 2.6%, not higher than 2.5%, not higher than 2.4%, not higher than 2.3%, not higher than 2.2%, not higher than 2.1%, not higher than 2%, not higher than 1.9%, not higher than 1.85%, not higher than 1.8%, or not higher than 1.75%.
(16) The weight percentage of Ni in the alloy of the present invention is at least 0.1%, e.g., at least 0.15%, at least 0.25%, at least 0.5%, at least 1%, at least 1.5%, at least 1.7%, at least 1.8%, at least 1.9%, at least 2%, at least 2.2%, at least 2.4%, at least 2.6%, or at least 2.8%, but not higher than 7.5%, e.g., not higher than 7%, not higher than 6.8%, not higher than 6.6%, not higher than 6.4%, or not higher than 6.2%. In the embodiments (i) set forth above the weight percentage of Ni usually is at least 4%, e.g., at least 4.2%, at least 4.5%, or at least 4.8%, but not higher than 7.5%, e.g., not higher than 7%, not higher than 6.8%, not higher than 6.6%, not higher than 6.4%, or not higher than 6.2%. In the embodiments (ii) set forth above the weight percentage of Ni usually is at least 0.1%, e.g., at least 0.15%, at least 0.25%, at least 0.5%, at least 1%, at least 1.5%, at least 1.7%, at least 1.8%, at least 1.9%, at least 2%, at least 2.2%, at least 2.4%, at least 2.6%, or at least 2.8%, but not higher than 4%, e.g., not higher than 3.8%, not higher than 3.5%, not higher than 3.3%, or not higher than 3%. In the embodiments (iii) set forth above the weight percentage of Ni usually is at least 0.1%, e.g., at least 0.15%, at least 0.25%, at least 0.5%, at least 1%, at least 1.5%, at least 1.7%, at least 1.8%, at least 1.9%, at least 2%, at least 2.2%, at least 2.4%, at least 2.6%, or at least 2.8%, but not higher than 3.5%, e.g., not higher than 3.3%, not higher than 3.2%, not higher than 3.1%, or not higher than 3%. In the embodiments (iv) set forth above the weight percentage of Ni usually is at least 0.1%, e.g., at least 0.15%, at least 0.25%, at least 0.5%, at least 1%, at least 1.5%, at least 1.7%, at least 1.8%, at least 1.9%, at least 2%, at least 2.2%, at least 2.4%, at least 2.6%, or at least 2.8%, but not higher than 3.5%, e.g., not higher than 3.3%, not higher than 3.2%, not higher than 3.1%, or not higher than 3%.
(17) The weight percentage of Si in the alloy of the present invention is at least 0.1%, e.g., at least 0.15%, at least 0.25%, at least 0.5%, at least 1%, at least 1.5%, at least 1.7%, at least 1.8%, at least 1.9%, at least 2%, at least 2.1%, or at least 2.3%, but not higher than 4%, e.g., not higher than 3.8%, not higher than 3.6%, not higher than 3.4%, not higher than 3.2%, or not higher than 3%. In the embodiments (i) set forth above the weight percentage of Si usually is at least 1.6%, e.g., at least 1.65%, at least 1.7%, or at least 1.8%, but not higher than 2.8%, e.g., not higher than 2.7%, not higher than 2.6%, not higher than 2.5%, not higher than 2.4%, or not higher than 2.3%. In the embodiments (ii) set forth above the weight percentage of Si usually is at least 1.6%, e.g., at least 1.65%, at least 1.7%, or at least 1.8%, but not higher than 2.8%, e.g., not higher than 2.7%, not higher than 2.6%, not higher than 2.5%, not higher than 2.4%, or not higher than 2.3%. In the embodiments (iii) set forth above the weight percentage of Si usually is at least 1.6%, e.g., at least 1.65%, at least 1.7%, or at least 1.8%, but not higher than 2.8%, e.g., not higher than 2.7%, not higher than 2.6%, not higher than 2.5%, not higher than 2.4%, or not higher than 2.3%. In the embodiments (iv) set forth above the weight percentage of Si usually is at least 1.6%, e.g., at least 1.65%, at least 1.7%, or at least 1.8%, but not higher than 3.5%, e.g., not higher than 3.3%, not higher than 3.2%, not higher than 3.1%, or not higher than 3%.
(18) The alloy of the present invention usually comprises one or more additional elements, i.e., in addition to Fe, Cr, C, B, N, Ni and Si. For example, often the alloy will also comprise at least one or more (and frequently all or all but one) of V, Mn, Mo, Nb, Ti and Al. However, other elements such as one or more of W, Co, Cu, Mg, Ca, Ta, Zr, Hf, rare earth elements may (and often will) be present as well.
(19) The alloy of the present invention usually comprises at least V as additional element. If employed, the weight percentage of V usually is at least 2%, e.g., at least 3%, at least 3.5%, at least 3.8%, at least 4%, at least 4.2%, or at least 4.5%, but usually not more than 12%, e.g., not more than 10%, not more than 8%, not more than 7.5%, or not more than 7%. Additionally, it is preferred for V to be present in weight percentages from 1.1 to 1.5 times (in particular from 1.1 to 1.4 times, or from 1.1 to 1.3 times) the combined weight percentage of C and N. As a general rule, the preferred concentration of V decreases with increasing concentration of Cr (while the preferred concentration of N increases with increasing concentration of Cr). In the case of embodiment (i) set forth above, V is usually present in weight percentages of not higher than 4%, e.g., not higher than 3.7%, not higher than 3.5%, or not higher than 3%, whereas in the case of embodiments (ii) to (iv) set forth above, V is usually present in weight percentages of not higher than 5%, e.g., not higher than 4.5%, not higher than 4.2%, or not higher than 4%.
(20) If employed, Mn is usually present in the alloy of the present invention in a weight percentage of at least 0.1%, e.g., at least 0.3%, at least 0.5%, at least 0.8%, at least 1%, or at least 1.1%, but usually not higher than 8%, e.g., not higher than 7%, not higher than 6%, not higher than 5%, not higher than 4%, or not higher than 3%. In the embodiments (i) set forth above the weight percentage of Mn usually is at least 0.1%, e.g., at least 0.3%, at least 0.5%, at least 0.7%, or at least 0.8%, but not higher than 3%, e.g., not higher than 2.9%, not higher than 2.8%, not higher than 2.7%, not higher than 2.6%, or not higher than 2.5%. In the embodiments (ii) set forth above the weight percentage of Mn usually is at least 0.1%, e.g., at least 0.3%, at least 0.5%, at least 0.7%, or at least 0.8%, but not higher than 5%, e.g., not higher than 4.8%, not higher than 4.5%, not higher than 4.2%, or not higher than 4%. In the embodiments (iii) set forth above the weight percentage of Mn usually is at least 0.1%, e.g., at least 0.3%, at least 0.5%, at least 0.7%, or at least 0.8%, but not higher than 6%, e.g., not higher than 5.8%, not higher than 5.5%, not higher than 5.2%, or not higher than 5%. In the embodiments (iv) set forth above the weight percentage of Mn usually is at least 0.1%, e.g., at least 0.3%, at least 0.5%, at least 0.7%, or at least 0.8%, but not higher than 8%, e.g., not higher than 7.5%, not higher than 7%, not higher than 6.8%, or not higher than 6.5%.
(21) If employed, Co is usually present in the alloy of the present invention in a weight percentage of at least 0.1%, e.g., at least 0.15%, at least 0.2%, at least 0.25%, or at least 0.3%, but usually not higher than 4%, e.g., not higher than 3%, not higher than 2%, not higher than 1.5%, not higher than 1%, or not higher than 0.5%.
(22) If employed, Cu is usually present in the alloy of the present invention in a weight percentage of at least 0.1%, e.g., at least 0.2%, at least 0.3%, at least 0.4%, at least 0.45%, or at least 0.5%, but usually not higher than 4.5%, e.g., not higher than 4%, not higher than 3%, not higher than 2%, not higher than 1.5%, or not higher than 1.2%.
(23) If employed, Mo and/or W are usually present in the alloy of the present invention in a combined weight percentage of at least 0.3%, e.g., at least 0.5%, at least 0.6%, or at least 0.7%, but usually not higher than 6%, e.g., not higher than 5%, not higher than 4%, not higher than 3.5%, or not higher than 3%. If only one of Mo and W is to be present, preference is usually given to Mo, which in this case is usually present in weight percentages not higher than 5%, e.g., not higher than 4%, not higher than 3.5%, or not higher than 3. Further, in the case of embodiments (i) set forth above, Mo is usually present in percentages by weight of not higher than 1%, e.g., not higher than 0.8%, not higher than 0.6%, or not higher than 0.5%. In the case of embodiments (ii) to (iv) set forth above, Mo is usually present in percentages by weight of not higher than 3%, e.g., not higher than 2.7%, not higher than 2.3%, or not higher than 2%.
(24) If employed, Nb is usually present in the alloy of the present invention in a weight percentage of at least 0.01%, e.g., at least 0.05%, at least 0.1%, at least 0.2%, at least 0.3%, at least 0.4%, or at least 0.5%, but usually not higher than 6%, e.g., not higher than 4%, not higher than 3%, not higher than 2%, or not higher than 1%. In embodiments (i) to (iv) set forth above, Nb will usually be present in weight percentages of not more than 2%, e.g., not more than 1.5%, or not more than 1%.
(25) If employed, Ti will usually be present in the alloy of the present invention in a weight percentage of at least 0.01%, e.g., at least 0.05%, at least 0.1%, at least 0.2%, at least 0.3%, at least 0.4%, or at least 0.5%, but usually not higher than 5%, e.g., not higher than 4%, not higher than 3%, not higher than 2%, or not higher than 1%. In embodiments (i) to (iv) set forth above, Ti will usually be present in weight percentages of not more than 3%, e.g., not more than 2.5%, not more than 2%, or not more than 1%.
(26) If employed, Zr will usually be present in the alloy of the present invention in a weight percentage of at least 0.01%, e.g., at least 0.02%, at least 0.03%, at least 0.04%, at least 0.05%, or at least 0.1%, but usually not higher than 2%, e.g., not higher than 1.8%, not higher than 1.6%, not higher than 1.3%, or not higher than 1%.
(27) If employed, Al will usually be present in the alloy of the present invention in a weight percentage of at least 0.01%, e.g., at least 0.02%, at least 0.03%, at least 0.04%, at least 0.05%, at least 0.1%, at least 0.2%, at least 0.3%, or at least 0.4%, but usually not higher than 2%, e.g., not higher than 1.5%, not higher than 1%, not higher than 0.9%, or not higher than 0.8%. In embodiment (i) set forth above Al will usually be present in weight percentages of not more than 2%, e.g., not higher than 1.7%, not higher than 1.5%, or not higher than 1.3%. In embodiments (ii) to (iv) set forth above Al will usually be present in weight percentages of not higher than 1.5%, e.g., not higher than 1.3%, not higher than 1%, or not higher than 0.9%. If Al is present, B is preferably present in a weight percentage that is at least 1.8 times, e.g., at least 1.9 times, or at least 2 times, but not higher than 2.5 times, e.g. not higher than 2.4 times, or not higher than 2.3 times the weight percentage of Al in order to obtain a satisfactory hardness of the alloy in the as cast state.
(28) If employed at all, Mg and/or Ca are usually present in the alloy of the present invention in a combined weight percentage of at least 0.01%, e.g., at least 0.02%, at least 0.03%, or at least 0.04%, but usually not higher than 0.2%, e.g., not higher than 0.18%, not higher than 0.15%, or not higher than 0.12%. Each of Mg and Ca may be present in an individual weight percentage of at least 0.02% and not higher than 0.08%.
(29) If employed, one or more rare earth elements are usually present in the alloy of the present invention in a combined weight percentage of at least 0.05%, e.g., at least 0.08%, at least 0.1%, or at least 0.15%, but usually not higher than 2%, e.g., not higher than 1%, not higher than 0.9%, or not higher than 0.8%.
(30) If employed, Ta, Zr, Hf, and Al are usually present in the alloy of the present invention in a combined weight percentage of at least 0.01%, e.g., at least 0.05%, at least 0.08%, or at least 0.1%, but usually not higher than 3%, e.g., not higher than 2.5%, not higher than 2%, or not higher than 1.5%.
(31) Among the unavoidable impurities which are usually present in the alloy of the present invention, sulfur and phosphorus may be mentioned. Their concentrations are preferably not higher than 0.2%, e.g., not higher than 0.1%, or not higher than 0.06% by weight each.
(32) The alloy of the present invention is particularly suitable for the production of parts which are to have a high wear (abrasion) resistance and are suitably produced by a process such as sand casting. Non-limiting examples of such parts include slurry pump components, such as casings, impellers, suction liners, pipes, nozzles, agitators, valve blades. Other components which may suitably be made, at least in part, from the alloy of the present invention include, for example, shell liners and lifter bars in ball mills and autogenous grinding mills, and components of coal pulverizers.
(33) Any conventional casting technology may be used to produce the alloy of the present invention. For example, the alloy may be cast into sand molds (referred to herein as as cast state). Alternatively, the alloy may be subjected to chill casting, for example, by pouring the alloy into a copper mold. This often affords a hardness which is significantly higher (e.g., by at least 20, and in some cases at least 50 Brinell units) than the hardness obtained by casting into a sand mold. Additionally, the cast alloy may be heat-treated at a temperature in the range of, for example, from 1800 to 2000 F., followed by air cooling, although this is usually not preferred or necessary, respectively. If a hardening treatment is to be carried out, the preferred hardening method for the alloy of the present invention is by cryogenic treatment: cooling to a temperature of, for example, 100 to 300 F., and maintaining at this temperature for a time of, for example one hour per one inch of casting wall thickness. The cryogenic tempering process may be performed with equipment and machinery that is conventional in the thermal cycling treatment field. First, the articles-under-treatment are placed in a treatment chamber which is connected to a supply of cryogenic fluid, such as liquid nitrogen or a similar low temperature fluid. Exposure of the chamber to the influence of the cryogenic fluid lowers the temperature until the desired level is reached.
EXAMPLES
Examples 1 to 5
(34) Five alloys having the chemical compositions set forth in Table 1 below (in % by weight, S<0.025, P<0.1, Fe:Bal.) were melted in a 30 kg high frequency induction furnace. The initial charge materials were steel scrap, ferroalloy and pig iron. The melt temperature was controlled at 2700 F. to 2790 F. After all the charge materials had melted in the furnace, the liquidus temperature of the alloy was determined to be: Alloy 12197.4 F. Alloy 22185.7 F., Alloy 32165 F., Alloy 42167.4 F., Alloy 52199.9 F. Then the molten alloys were poured at a temperature of 2400 F.10 F. into sand molds with dimensions of 20 mm20 mm110 mm to obtain four samples for testing for each alloy. In addition for chill casting each alloy was poured into a copper mold (30 mm diameter35 mm height). The castings were cooled to ambient temperature both in the sand molds and the chill molds.
(35) TABLE-US-00001 TABLE 1 Alloy No. C Si Mn Cr Ni Mo V Ti Nb N B Al 1 (compar- 3.78 2.2 1.5 8.8 5.6 0.43 2.2 0.45 0.77 0.013 0.0 0.67 ative) 2 3.73 2.3 1.6 8.4 5.64 0.34 2.1 0.41 0.80 0.03 1.55 0.62 3 3.86 2.23 1.4 8.2 5.55 0.22 2.0 0.47 0.88 0.04 1.28 0.64 4 3.95 2.25 1.55 8.1 5.73 0.13 1.8 0.02 0.91 0.045 1.30 0.71 5 4.34 2.23 1.6 8.5 5.85 0.33 2.34 0.98 0.63 0.048 1.46 0.81
Test Results:
(36) All four of the samples made with Alloy No. 1 exhibited cracks throughout their length of 110 mm. This is probably due to the following reaction which proceeds at room temperature: Al.sub.4C.sub.3+12 H.sub.2O.fwdarw.4 Al(OH).sub.3+3 CH.sub.4. The cracks are likely caused by the pressure of the evolved methane gas and the fact that the volume of the reaction product Al(OH).sub.3 is about 15 times higher than the volume of Al.sub.4C.sub.3. The chill sample developed surface cracks during the Brinell hardness testing and indentation. By contrast, all samples made with Alloy Nos. 2-5 were crack free.
(37) The Brinell (HB) hardness values (10 mm tungsten ball and load of 3000 kgf) measured on the samples (cast in sand mold, cast in chill mold, and in each case also after cryogenic hardening) are set forth in Table 2 below. Table 2 also sets forth the Rockwell (HRC) and Vickers (HV) hardness values which were obtained by conversion from the HB values. The HB value of Alloy No. 5 after chill casting and cryogenic hardening was too high for conventional measurement and was obtained by using a micro indenter (1000 g/f).
(38) TABLE-US-00002 TABLE 2 Sand cast Chill cast plus plus Alloy cryogenic cryogenic Com- No. Sand cast hardening Chill cast hardening ments 1 555 HB, 650 HB 575 HB 713 HB Cracks 54 HRC 59 HRC 55.7 HRC 62.5 HRC 580 HV 680 HV 610 HV 760 HV 2 744 HB 780 HB 780 HB 812 HB No 63 HRC 64.5 HRC 64.5 HRC 67 HRC cracks 780 HV 810 HV 810 HV 900 HV 3 780 HB 812 HB 812 HB, 850 HB, No 64.5 HRC 67 HRC 67 HRC 67.5 HRC cracks 810 HV 900 HV 900 HV 920 HV 4 812 HB 850 HB, 812 HB, 890 HB, No 67 HRC 67.5 HRC 67 HRC 68 HRC cracks 900 HV 920 HV 900 HV 940 HV 5 850 HB, 890 HB 890 HB 945 HB No 67.5 HRC 68 HRC 68 HRC N/A HRC cracks 920 HV 940 HV 940 HV 1068 HV
(39) The CBNVF values for Alloy Nos. 1-5 were determined according to the equations provided above and are set forth in Table 3 below. For example, the value for Alloy No. 4 was determined as follows:
C.sub.E=% C+% N+(f% B)=3.95+0.045+(2.21.3)=3.995+2.86=6.855
CBNVF=C.sub.E12.33+(% Cr+% M)0.5515.2=6.85512.33+(8.1+0.13+1.8+0.02+0.91)0.5515.2==84.52 +(10.960.55)15.2=84.52+6.0315.2=75.35
(40) TABLE-US-00003 TABLE 3 Alloy No. 1 2 3 4 5 (CBNVF) 38-7% 80 74 75 86 3 (%) graphite = 31 Comments Graphite No No No No ~7% graphite graphite graphite graphite
Microstructure Evaluation
(41)
Examples 6 to 15
(42) Ten alloys having the chemical compositions set forth in Table 4 below ((in % by weight, S<0.025, P<0.1, Fe:Bal.) were melted in a 30 kg high frequency induction furnace. The initial charge materials were steel scrap, ferroalloy and pig iron. The melt temperature was controlled at 2700 F. to 2790 F. Then the molten alloys were poured at a temperature of 2550 F.10 F. into sand molds with dimensions of 20 mm20 mm110 mm to obtain four samples for testing for each alloy. In addition for chill casting each alloy was poured into a copper mold (30 mm diameter35 mm height). The castings were cooled to ambient temperature both in the sand molds and the chill molds.
(43) TABLE-US-00004 TABLE 4 Alloy No. C Si Mn Cr Ni Mo V Ti Nb N B Al 6 4.3 1.66 3.5 14.1 1.5 1.6 3.1 0.5 0 0.12 0 0.38 (comp.) 7 3.9 1.95 3.6 13.7 2.2 1.5 3.3 0.46 0 0.11 1.13 0.45 8 4.1 2.1 3.9 17.5 2.1 1.6 3.8 0.18 0 0.10 0 0.03 (comp.) 9 3.7 2.4 3.1 17.2 2.03 1.48 3.7 0.4 0 0.08 1.34 0.44 10 4.0 1.7 4.3 25.9 2.2 1.2 3.3 0.38 0 0.18 0 0 (comp.) 11 3.8 1.9 4.1 24.8 1.9 1.1 3.5 0.44 0 0.15 1.28 0.39 12 4.3 2.2 4.7 31.3 1.8 0.7 4.4 0.55 1.2 0.34 0 0 (comp.) 13 4.0 2.3 5.2 32.1 2.2 0.55 4.5 0.66 0.9 0.28 1.23 0.36 14 3.6 2.1 6.1 38.9 1.9 0.46 6.9 0.33 0.89 0.56 0 0 (comp.) 15 3.45 2.2 6.6 37.8 1.8 0.55 6.7 0.43 0.8 0.42 1.1 0.5
Test Results:
(44) All four of the samples made from Alloy No. 6 had developed cracks throughout their length of 110 mm, presumably due to the reaction set forth above. The samples made from Alloy Nos. 7-15 were crack free.
(45) The Brinell (HB) hardness values measured on the samples (cast in sand mold, cast in chill mold, and in each case also after cryogenic hardening) are set forth in Table 5 below. Table 5 also sets forth the Rockwell (HRC) and Vickers (HV) hardness values which were obtained by conversion from the HB values.
(46) TABLE-US-00005 TABLE 5 Sand cast Chill cast plus plus Alloy cryogenic cryogenic Com- No. Sand cast hardening Chill cast hardening ments 6 555 HB 600 HB N/A N/A Cracks 54 HRC 57 HRC 585 HV 630 HV 7 713 HB 780 HB 880 HB 940 HB 62.5 HRC 64.5 HRC 68 HRC N/A HRC 760 HV 810 HV 940 HV 1068 HV 8 555 HB 600 HB 650 HB 680 HB 54 HRC 57 HRC 59 HRC 60 HRC 585 HV 630 HV 680 HV 711 HV 9 812 HB 880 HB 890 HB 940 HB 67 HRC 68 HRC 68 HRC N/A HRC 900 HV 940 HV 940 HV 1068 HV 10 600 HB 650 HB 650 HB 680 HB 57 HRC 59 HRC 59 HRC 60 HRC 630 HV 680 HV 680 HV 711 HV 11 812 HB 880 HB 890 HB 940 HB 67 HRC 68 HRC 68 HRC N/A HRC 900 HV 940 HV 940 HV 1068 HV 12 680 HB 713 HB, cracks N/A 60 HRC 62.5 HRC 711 HV 760 HV 13 812 HB 880 HB 890 HB 940 HB 67 HRC 68 HRC 68 HRC N/A HRC 900 HV 940 HV 940 HV 1068 HV 14 680 HB 713 HB cracks N/A 60 HRC 62.5 HRC 711 HV 760 HV 15 880 HB 940 HB 940 HB 1147 HV 68 HRC N/A HRC N/A HRC 940 HV 1068 HV 1068 HV
(47) The CBNVF values for Alloy Nos. 6-15 were determined according to the equations provided above and are set forth in Table 6 below.
(48) TABLE-US-00006 TABLE 6 Alloy No. 6 7 8 9 10 11 12 13 14 15 (CBNVF) 48 75 49 80 53 84 62 92 62 88 3 (%) Comments Al.sub.4C.sub.3
Examples 16 to 19
(49) Large castings for a 3400 lbs. suction liner were made from the four alloys whose composition (in % by weight, S<0.025, P<0.1, Fe:Bal.) is set forth in Table 7 below.
(50) TABLE-US-00007 TABLE 7 Alloy No. C Si Mn Cr Ni Mo V Ti Nb N B Al 16 4.55 2.29 0.9 9.23 6.7 0.28 3.05 0.65 0.00 0.04 0.48 0.14 17 3.11 2.37 0.93 8.48 6.36 0.27 2.73 0.62 0.02 0.036 1.88 0.3 18 4.41 2.3 4.7 33.2 0.16 0.96 5.19 0.04 0.00 0.31 0.22 0.02 19 3.93 1.8 6.2 29.5 1.8 0.55 7.1 0.2 0.00 0.24 0.55 0.06
(51) The Brinell (HB) hardness values measured on the samples (cast in sand mold, cast in chill mold, and in each case also after cryogenic hardening) are set forth in Table 8 below.
(52) TABLE-US-00008 TABLE 8 Sand cast Chill cast plus plus Alloy cryogenic cryogenic Com- No. Sand cast hardening Chill cast hardening ments 16 744 HB 782 HB 782 HB 852 RB 17 782 HB 812 HB 852 HB 940 HB 18 744 HB 760 HB 782 HB 812 HB 19 744 744 HB 812 HB 852 HB
(53) The CBNVF values for Alloy Nos. 16-19 were determined according to the equations provided above and are set forth in Table 9 below.
(54) TABLE-US-00009 TABLE 9 Alloy No. 16 17 18 19 (CBNVF) 56 91 68 67 3 (%)
(55) It is noted that the foregoing examples have been provided merely for the purpose of explanation and is in no way to be construed as limiting of the present invention. While the present invention has been described with reference to exemplary embodiments, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.