CEMENTED CARBIDE FOR HIGH DEMAND APPLICATIONS

Abstract

Provided is a corrosion and erosion resistant cemented carbide for high demand including, for example, oil and gas flow applications. The cemented carbide grade may include, for example, including the following constituents Co, Ni, Cr, Mo and WC. The binder phase content of the cemented carbide is between 5.1 to 7.5 wt %. The wt % of Co in the cemented carbide may be less than the wt % of Ni.

Claims

1. A cemented carbide having a hard phase and a binder phase, the cemented carbide comprising: Co present in an amount of 1.7-3.3 by wt % of the cemented carbide; Ni present in an amount of 2.0-3.7 by wt % of the cemented carbide; Cr present in an amount of 0.5-1.1 by wt % of the cemented carbide; Mo present in an amount of 0.05-0.4 by wt % of the cemented carbide; and WC present in an amount of 90.0-96.0 by wt % of the cemented carbide, wherein the binder phase is present in an amount from 5.1 to 7.5 by wt % of the cemented carbide, and wherein the Co is present in an amount less than the Ni.

2. The cemented carbide of claim 1, wherein a quotient wt % of Co/Ni in the cemented carbide is 0.5 to 0.95.

3. The cemented carbide of claim 1, wherein a quotient wt % of Cr/(Co+Ni+Cr+Mo) in the cemented carbide is 0.08 to 0.14.

4. The cemented carbide of claim 1, wherein a quotient wt % Mo/(Co+Ni+Cr+Mo) in the cemented carbide is 0.01 to 0.06.

5. The cemented carbide of claim 1, wherein the binder phase is present in an amount of 6.2 to 7.2 by wt % of the cemented carbide.

6. The cemented carbide of claim 1, wherein the Co+Ni content in the cemented carbide is at least 4 wt %.

7. The cemented carbide of claim 1, wherein the WC has a grain size of from 0.2 to 2 μm determined by linear intercept.

8. The cemented carbide of claim 7, wherein the grain size of WC is in a range of from 0.3 to 0.9 μm determined by linear intercept.

9. The cemented carbide of claim 1, wherein the Co is present in an amount of from 1.7 to 2.6 by wt %.

10. The cemented carbide of claim 1, wherein the Ni is present in an amount of from 3.3 to 3.7 by wt %.

11. The cemented carbide of claim 1, wherein the Cr is present in an amount of from 0.7 to 1.0 by wt %.

12. The cemented carbide of in claim 1, wherein the Mo is present in an amount of from 0.1 to 0.3 by wt %.

13. A component for oil and gas applications comprising the cemented carbide of claim 1.

14. The component of claim 13, comprising a choke valve, a control valve, a valve seat, a plug seat, a frac seat, a cage, a cage assembly, a seal ring, a component part of a valve to allow the through-flow of a fluid or a slurry.

15. A tool for metal forming comprising the cemented carbide of claim 1.

16. A component for fluid handling comprising the cemented claim 1.

17. A method of making a cemented carbide article having a hard phase including-WC and a binder phase, the method comprising: preparing a powdered batch comprising raw materials in wt % of 1.7-3.3 Co; 2.0-3.7 Ni; 0.5-1.1 Cr, 0.05-0.4 Mo and 90.0-96.0 wt % WC by weight of the cemented carbide article, wherein the Co is present in an amount less than the Ni; pressing the powdered batch to form a pre-form; and sintering the pre-form to form the cemented carbide article; wherein the binder phase content of the cemented carbide article is present in an amount of from 5.1 to 7.5 b wt % of the cemented carbide article.

18. The method of claim 17, wherein the sintering the pre-form to form the article comprises vacuum or HIP processing.

19. The method of claim 17, wherein the sintering comprises processing at a temperature 1360-1500° C. and a pressure 0-20 MPa.

20-21. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0044] A specific implementation of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:

[0045] FIG. 1 is a graph of normalised mass loss and toughness for different example materials according to aspects of the present invention in addition to comparative examples.

DETAILED DESCRIPTION

[0046] A wear resistant cemented carbide grade is provided with relative high toughness and exhibiting enhanced corrosion and erosion resistance. The inventors have identified that such physical and mechanical characteristics may be achieved via a binder phase content relative to a WC hard phase of in the range 5.1 to 7.5 wt % and in which the cemented carbide has a wt % composition 1.7-3.3 Co; 2.0-3.7 Ni; 0.5-1.1 Cr, 0.05-0.4 Mo with 90.0-96.0 WC. A contribution to the desired physical and mechanical characteristics may be achieved also by controlling the amount of Co relative to Ni and in particular by maintaining a wt % Co being less than wt % Ni.

[0047] The present cemented carbide is specifically adapted for potential high wear and high demand applications including use as a component within oil and gas production with such components being susceptible to corrosion and mechanical erosion. Additionally, the present carbide is also suitable for the use as a tool for metal forming.

Examples

[0048] Conventional powder metallurgical methods including milling, pressing, shaping and sinter hipping were used to manufacture a cemented carbide according to the present invention. Cemented carbide materials according to the present invention were prepared in addition to comparative test coupons.

[0049] Each of the sample mixtures Grades A to I were prepared from powders forming the hard constituents and powders forming the binder. The following preparation method corresponds to Grade B of Table 1 below having starting powdered materials: WC 95.24 g, Cr3C2 0.82 g, Co 2.05 g, Ni 3.58 g, C 0.05 g, Mo 0.31 g, PEG 2 g, Ethanol 50 ml. It will be appreciated by those skilled in the art that it is the relative amounts of the powdered materials that allow the skilled person and suitable adjustment is needed to make the powdered batch and achieve the final fully sintered composition of the cemented carbides of Table 1.

[0050] The powders were wet milled together with the lubricant and the anti-flocculating agent until a homogeneous mixture was obtained and granulated by drying and sieving. The dried powder was pressed to form a green part according to the abovementioned standard shapes and sintered using SinterHIP at 1350-1500° C. and 5 MPa.

[0051] Table 1 details composition (wt %) together with additional characterisations of grades A to I in accordance with the present invention.

TABLE-US-00001 TABLE 1 Example grade material compositions A to I according to the present invention. Total WC Raw Cr.sub.3C.sub.2/ Mo/ Composition, wt % binder Material Binder Binder Grade WC Co Cr.sub.3C.sub.2 Ni Mo wt % um Tot Tot Co/Ni A 93.80 1.75 0.75 3.50 0.20 6.20 0.8 0.12 0.03 0.50 B 93.40 2.00 0.80 3.50 0.30 6.60 0.8 0.12 0.05 0.57 C 93.00 3.00 0.85 3.00 0.15 7.00 0.8 0.12 0.02 1.00 D 93.80 1.75 0.75 3.50 0.20 6.20 1 0.12 0.03 0.50 E 93.00 3.00 0.85 3.00 0.15 7.00 1 0.12 0.02 1.00 F 93 2.30 1.00 3.50 0.20 7.00 0.8 0.14 0.03 0.66 G 93 2.30 1.00 3.50 0.20 7.00 1 0.14 0.03 0.66 H 93 2.00 1.10 3.65 0.35 7.10 1 0.15 0.05 0.55 I 93 2.00 1.00 3.65 0.35 7.00 1 0.14 0.05 0.55

[0052] Hardness tests were carried out on grades A to I in accordance with ISO 3878 and toughness testing according to Palmqvist, ISO 28079. Vickers indentation test was performed using 30 kgf (HV30) to assess hardness. Palmqvist fracture toughness was calculated according to:

[00001]$K1c=A\sqrt{HV}\sqrt{\frac{P}{.Math.L}}$

[0053] Where A is a constant of 0.0028, HV is the Vickers hardness in N/mm2, P is the applied load (N) and ΣL is the sum of crack lengths (mm) of the imprint. The results are shown in table 2.

TABLE-US-00002 TABLE 2 Hardness and toughness tests for sample grades A to I. Grade HV30 KIC A 1799 9.2 B 1843 9.2 C 1831 9.2 D 1753 9.1 E 1700 9.4 F 1907 9 G 1768 10.3 H 1728 9.2 I 1688 9.3

[0054] Table 3 details example grades B and G together with comparative examples 1 to 4 according to various different compositions and WC starting material particle sizes. It will be appreciated the particle size of the starting material is reduced according to standard milling and sintering procedures such that the grain size of the final fully sintered material (determined by linear intercept) may be less than (up to or approximately half) the particle size of the starting material as determined by Fisher Model 95 Sub-Sieve Sizer™ (FSSS).

[0055] The linear intercept method (ISO 4499-2:2008) is a method of measurement of WC grain size. Grain-size measurements are obtained from SEM images of the microstructure. For a nominally two-phase material such as a cemented carbide (hard phase and binder phase), the linear-intercept technique gives information of the grain-size distribution. A line is drawn across a calibrated image of the microstructure of the cemented carbide. Where this line intercepts a grain of WC, the length of the line (l.sub.i) is measured using a calibrated rule (where i=1,2,3, . . . n for the first 1.sup.st, 2.sup.nd, 3.sup.rd, . . . , nth grain). At least 100 grains where counted for the measurements. The average WC grain size will be defined as:

d.sub.WC=Σl.sub.i/n

TABLE-US-00003 TABLE 3 Compositions of example grades B and G with various comparative examples 1 WC Raw Material, Grade WC Co Cr.sub.3C.sub.2 Ni Mo um B 93.40 2.00 0.80 3.50 0.30 0.8 G 93 2.30 1.00 3.50 0.20 1 Comparative 1 87.8 3.5 1.5 7 0.2 0.8 Comparative 2 93.85 6 0.15 0 0 2 Comparative 3 96.95 1.9 0.35 0.7 0.1 0.9 Comparative 4 94.9 3.3 0.6 1.1 0.1 0.8

[0056] Hardness (ISO 3878), toughness (Palmqvist, ISO 28079) and TRS (ISO 3327:2009) tests were undertaken on grades B and G (partially), as well as comparative examples to 4. The test pieces for transverse rupture strength's determination were cylinders of Type C (cylindrical cross-section with 40×3 mm2 dimension). The samples were placed between two supports and loaded in their center until fracture occurred (3-points bending). The maximum load was recorded and averaged over minimum five samples per test. The results are sown in table 4 together with respective magnetic cobalt content.

TABLE-US-00004 TABLE 4 Physical and mechanical performance test results together with magnetic cobalt content of the grades B and G together with comparative examples 1 to 4. Magnetic Co content, Grade wt % HV30 KIC TRS B 1.93 1843 9.2 3800 G 2.00 1768 10.3 3800 Comparative 1 2.75 1540 10.3 3300 Comparative 2 5.4 1549 10.8 2870 Comparative 3 1.75 1949 8.4 3250 Comparative 4 3.05 1904 8.8 3800

[0057] The corrosion rate of grades B and G, and comparative examples 1 to 4 was assessed and the results are shown in table 5. The surface roughness (Ra) of the samples was 0.036 μm.

[0058] The corrosion rate in mm/year was estimated by means of mass loss against time of immersion under the following simulated test conditions: [0059] 1) Immersion for 212 h in synthetic sea water at pH 6 (3.56% wt. NaCl) at 25° C., in aerated conditions. [0060] 2) Immersion for 212 h in synthetic sea water at pH 1 (3.56% wt. NaCl+0.1M H.sub.2SO.sub.4) at 60° C., in aerated conditions.

[0061] The mass loss corrosion rate in mm/year was estimated according to the above simulated conditions using the formula (ASTM G31-72 ‘Standard Practice for Laboratory Immersion Corrosion Testing of Metals’):

Corrosion rate=8.76 10.sup.4×((weight loss (g)/(exposed surface area (cm.sup.2)×density (g/cm.sup.3)×immersion time (h))

TABLE-US-00005 TABLE 5 Corrosion testing results for grades B & G and comparative examples 1 to 4. Material loss (mm/year) in Material loss (mm/year) in synthetic seawater at pH6, synthetic seawater at pH1, Grade and 25° C. and 60° C. B 2.05 × 10.sup.−3 ± 0.40 × 10.sup.−3 71.10 × 10.sup.−3 ± 8.72 × 10.sup.−3 G 2.00 × 10.sup.−3 ± 0.78 × 10.sup.−3 85.61 × 10.sup.−3 ± 16.1 × 10.sup.−3 Comparative 1 4.14 × 10.sup.−3 ± 0.69 × 10.sup.−3 105.52 × 10.sup.−3 ± 12 × 10.sup.−3   Comparative 2 23.40 × 10.sup.−3 ± 0.52 × 10.sup.−3  163.2 × 10.sup.−3 ± 0.34 × 10.sup.−3 Comparative 3 2.02 × 10.sup.−3 ± 1.42 × 10.sup.−3 64.54 × 10.sup.−3 ± 2.87 × 10.sup.−3 Comparative 4 1.94 × 10.sup.−3 ± 0.96 × 10.sup.−3 94.05 × 10.sup.−3 ± 3.65 × 10.sup.−3

[0062] The dry erosion resistance of the grades of table 5 was tested using an air-sand erosion rig, following the ASTM G76-07 (‘Standard Test Method for Conducting Erosion Tests by Solid Particle Impingement Using Gas Jets’—determination of material loss by gas-entrained solid particle impingement erosion with jet nozzle type erosion equipment) as a guide. The particle size range was 181 μm-251 μm, impact angle 90°, erodent feed rate ˜10 g/min, flow velocity 200 f 20 m/s and stand-off distance between the sample and the nozzle 30 mm. The results are shown in Table 6.

TABLE-US-00006 TABLE 6 Dry erosion rate expressed as mm.sup.3/kg using air/sand erosion for grades B and G and comparative examples 1 to 4. Dry erosion rate Grade (mm.sup.3/kg sand) B 4.01 G 2.72 Comparative 1 10.84 Comparative 2 7.65 Comparative 3 2.24 Comparative 4 1.68

[0063] The present cemented carbide material according to grade G exhibited high wear (erosion resistance) in combination with enhanced toughness and corrosion resistance. In particular, FIG. 1 is a graph of normalized mass loss and toughness for invention grades B and G and comparative examples 1 to 4. Line 10 is the minimum toughness acceptance limit and line 11 is the minimum dry erosion resistance acceptance limit for high demand oil and gas exploration conditions. As will be noted, sample G satisfies both toughness and dry erosion requirements according to the testing methods described herein.

[0064] Unless defined otherwise all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the presently described subject matter pertains.

[0065] Unless otherwise indicated, any reference to “wt %” refers to the mass fraction of the component relative to the total mass of the cemented carbide.

[0066] Where a range of values is provided, for example, concentration ranges, percentage range or ratio ranges, it is understood that each intervening value, to the tenth of the unit of the lower limit, unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the described subject matter. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges, and such embodiments are also encompassed within the described subject matter, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the described subject matter.

[0067] It should be understood that the terms “a” and “an” as used above and elsewhere herein refer to “one or more” of the enumerated components. It will be clear to one of ordinary skill in the art that the use of the singular includes the plural unless specifically stated otherwise. Therefore, the terms “a”, “an” and “at least one” are used interchangeably in this application.

[0068] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as size, weight, reaction conditions and so forth used in the specification and 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 following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present subject matter. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0069] Throughout the application, descriptions of various embodiments use “comprising” language; however, it will be understood by one of skill in the art that, in some instances, an embodiment can alternatively be described using the language “consisting essentially of” or “consisting of”.

[0070] The present subject matter being thus described, it will be apparent that the same may be modified or varied in many ways. Such modifications and variations are not to be regarded as a departure from the spirit and scope of the present subject matter, and all such modifications and variations are intended to be included within the scope of the following claims.