Cemented carbide inserts for mining or cutting applications containing gamma phase carbides

Abstract

A sintered cemented carbide insert for mining or cutting applications, the insert having an average WC grain size of 0.8-18μm, a binder phase weight of 4-18wt%, a cubic gamma phase precursor having a gamma phase weight of 0.8-10wt%, optional unavoidable impurities and the balance WC, the difference between the hardness at any point 0.3mm from the surface of the insert and the hardness of the bulk is at least 25HV3, the hardness being measured according to ISO EN6507, and a method for producing said cemented carbide insert.

Description

[Technical field]

[0001] The present invention relates to a cemented carbide insert for mining or cutting applications comprising gamma phase carbides, and to a method for manufacturing said mining insert. [Background technology]

[0002] Cemented carbides have a unique combination of high elastic modulus, high hardness, high compressive strength, high wear resistance and good levels of toughness. Therefore, they are commonly used in products such as mining tools. Cemented carbides contain a hard metal phase and a binder phase. Typically, cemented carbides used in mining inserts use a tungsten carbide hard metal phase, with only very small amounts of other carbides present as impurities rather than deliberately added.

[0003] The use of gamma-phase hardmetals includes cubic carbides, nitrides and carbonitrides of titanium, tantalum and niobium carbide, which together with hexagonal tungsten carbide form mixed cubic carbides (Me1, Me2, Me3) (C) or mixed cubic carbonitrides (Me1, Me2, Me3) (C, N); the so-called gamma phases are commonly used in hardmetals used in the metal cutting industry, as they offer the advantages of improved wear resistance and improved resistance to plastic deformation. However, gamma-phase hardmetals are not currently used in hardmetals for mining inserts, as it makes the carbides brittle, which would cause premature cracking of the inserts when subjected to mining processes such as percussion drilling operations, thus shortening the life of the inserts.

[0004] definition By "hardmetal" herein is meant a material comprising at least 50% by weight of WC, possibly other hard constituents common in the art of making hardmetals, and a metallic binder phase preferably selected from one or more of Fe, Co, and Ni.

[0005] The term "bulk" as used herein refers to the cemented carbide in the innermost (middle) portion of the rock drilling insert, which in this disclosure is the zone having the lowest hardness.

[0006] The term "green" refers to a cemented carbide mining insert that is manufactured by grinding the hard phase components and binder together and then pressing the crushed powder to form a compact cemented carbide mining insert that has not yet been sintered.

[0007] The term "cubic carbides" refers to cubic carbides such as TaC, NbC, TiC, etc., which, together with hexagonal WC, form the cubic "gamma phase" during sintering.

[0008] The term "cubic nitride" refers to cubic nitrides such as TiN which, together with hexagonal WC, form the cubic "gamma phase" during sintering.

[0009] The term "cubic carbonitride" refers to cubic carbonitrides such as Ti(C,N) which, together with hexagonal WC, form the cubic "gamma phase" during sintering.

[0010] The term "gamma phase" refers to mixed cubic carbides and carbonitrides formed and precipitated during sintering when cubic carbide and / or nitride formers / precursors are added prior to the green forming step in amounts higher than can be dissolved in the binder in the sintered cemented carbide body. Typical cubic gamma phase formers / precursors are, for example, Ta, Nb, and Ti, which form cubic gamma phase, for example, together with W from hexagonal WC, but are not limited to (Ta,Nb,W)(C), (Ta,Nb,Ti,W)(C,N). Substantially all of the added cubic carbides / nitrides / carbonitrides form "gamma phase" and the amount of these cubic gamma phase precursors in the sintered body can be calculated from the sum of the added cubic carbides / nitrides / carbonitrides or back-calculated by analyzing the elemental concentrations of Me1, Me2 with nitrogen in the sintered body and assuming that all Me1 is added as Me1C, where Me1 is assumed to be the metal that forms cubic carbides as Ta or Nb. If nitrogen is present, some of Me2 is added as Me2N or Me2(C,N) and Me2C, where Me2 is the metal that forms both cubic carbides, nitrides and mixtures thereof as Ti. Elemental analysis is preferably performed using an XRF instrument with a wavelength dispersive spectrometer on the oxidized and dissolved sintered material, e.g. contained in light element (as boron) glass. Analysis and evaluation are performed using quantitative XRF methods with careful measurements within the scope of the claims. Summary of the Invention

[0011] Cemented carbide mining inserts have now been developed that have improved wear resistance without increasing brittleness. Various aspects of the invention, including a cemented carbide mining insert, a rock bit body including one or more attached cemented carbide inserts, and a method for manufacturing a cemented carbide insert, are characterized as set forth in the independent claims. Various embodiments of the invention are disclosed in the dependent claims.

[0012] According to a first aspect of the present invention, there is provided a sintered cemented carbide insert for mining or cutting applications, the sintered cemented carbide insert having an average WC grain size of 0.8-18 μm, a binder phase weight of 4-18 wt. %, a cubic gamma phase precursor gamma phase weight of 0.8-10 wt. %, optional unavoidable impurities, and balance WC, the difference between the hardness at any point 0.3 mm from the surface of the insert and the hardness of the bulk is at least 25 HV3, the hardness being measured according to ISO EN6507 3:2005.

[0013] Advantageously, a cemented carbide mining insert is provided with improved wear resistance without increased brittleness. Thus, the life of the insert is extended. Furthermore, it makes it easier to use recycled carbide, which has a higher gamma phase content than is acceptable for the cemented carbide grades typically used in mining or cutting applications. A cemented carbide insert should be considered to include any insert used for rock interaction, such as an insert for impact drilling, tophammer drilling, down-the-hole (DTH) drilling, a protective insert, or a cutting tool.

[0014] According to a second aspect of the present invention, there is provided a method for manufacturing a cemented carbide insert, comprising the steps of: a) providing a green cemented carbide insert comprising 0.8-10 wt. % cubic carbides and / or carbonitrides and / or nitrides, 4-18 wt. % binder, any unavoidable impurities, and the balance WC hard phase; b) sintering the green carbide mining insert to form a sintered cemented carbide insert; c) subjecting the sintered cemented carbide insert to a high energy post-treatment; The method includes:

[0015] Advantageously, this method produces cemented carbide inserts with improved wear resistance without increased brittleness, thus extending the life of inserts produced by this method.

[0016] According to a third aspect, there is provided a rock drilling bit body including one or more attached cemented carbide inserts. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram showing the locations on the insert where hardness and toughness measurements were taken. [Diagram 2] FIG. 1 is a schematic diagram of a tophammer bit with a ballistic insert with diameter measurement points indicated. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention relates to a sintered cemented carbide insert for mining or cutting applications, comprising an average WC grain size of 0.8-18 μm, 4-18 wt. % binder phase, 0.8-10 wt. % gamma phase of cubic gamma phase precursor, any unavoidable impurities, and the balance WC, wherein the difference between the hardness at any point 0.3 mm from the surface of the insert and the hardness of the bulk is at least 25 HV3, when the hardness is measured according to ISO EN6507.

[0019] Preferably, the sintered WC grain size is 0.8-16 μm, more preferably 0.8-8 μm, or 0.8-5 μm, or 0.9-8 μm, or 1.0-5 μm, or 1.0-4.0 μm.

[0020] The average WC grain size was estimated from at least two different micrographs for each material using the Jeffries method described below. The average value was then calculated from the average grain size values ​​obtained from the individual micrographs (each for each material). The procedure for average grain size estimation using the modified Jeffries method was as follows:

[0021] A rectangular frame of appropriate size was selected within the SEM micrograph to contain a minimum of 300 WC grains. Grains within the frame and those intersected by the frame were counted manually and the average grain size was obtained from equation (1-3): TIFF2024527394000002.tif76170[In the formula, d=average WC grain size (μm) L1, L2 = Frame side length (mm) M=Magnification L scale mm = Length measured in mm of scale bar on micrograph L scale micro = Actual length of scale bar relative to magnification (μm) n1 = number of complete particles in the frame n2 = number of particles crossing the frame boundary wt%Co = known cobalt content in weight percent].

[0022] Equation (2) is used to estimate the WC fraction based on the known Co content in the material. Equation (3) then yields the average WC grain size from the ratio of the total WC area in the frame to the number of grains it contains. Equation (3) also includes a correction factor to account for the fact that in any 2D cross section, all grains do not divide their maximum diameter.

[0023] Preferably, the binder phase is 4-18% by weight, or 5-15% by weight, or 5-12% by weight, or 6-12% by weight, or 5-8% by weight, and 10-15% by weight.

[0024] For top hammer (TH) and down the hole (DTH) impact applications, the particle size is preferably 0.8-5 microns, the binder phase concentration is preferably 4-8 wt. % and the room temperature hardness is preferably 1250-1650 HV20.

[0025] For rotary applications the particle size is preferably 2-8 microns, the binder phase content is preferably 8-15 wt. % and the room temperature hardness is 1000-1400 HV20.

[0026] For mechanical cutting applications the particle size is preferably 6-18 microns, the binder phase content is preferably 6-18 wt. % and the room temperature hardness is preferably 800-1200 HV20.

[0027] Preferably the weight percentage of gamma phase is less than 10% by weight, more preferably less than 8% by weight, even more preferably less than 6% by weight, or less than 4% by weight, or less than 2% by weight.

[0028] Preferably the weight percentage of gamma phase is greater than 0.8 weight percent, more preferably greater than 0.9 weight percent, more preferably greater than 1.0 weight percent, even more preferably greater than 1.1 weight percent, and even more preferably greater than 1.2 weight percent.

[0029] The gamma phase forming carbide or nitride or carbonitride added may be any of Ta, Nb, Ti, Zr, and Hf.

[0030] Preferably the volume of gamma phase is evenly distributed throughout the insert.

[0031] Preferably, the gamma phase particles are less than 10 microns, more preferably less than 5 microns, preferably less than 4 microns, and most preferably less than 3 microns.

[0032] The hardness of the cemented carbide inserts is measured using Vickers hardness testing. The cemented carbide body is split along its longitudinal axis and ground using standard techniques. The split is made with a diamond disc cutter under running water.

[0033] In one embodiment, the difference between the hardness at any point on the surface of the dome of the rock drilling insert at a depth of 0.3 mm and the minimum hardness of the bulk of the rock drilling insert is at least 25HV3 or at least 30HV3, or at least 35HV3, or at least 40HV3. The average hardness at a depth is defined as the average of at least 10, more preferably 20, hardness values ​​measured at a certain depth, uniformly distributed around the insert. A large hardness difference between the surface of the rock drilling insert and its interior is present over the entire surface, thus further reducing the risk of other types of breakage during handling.

[0034] Preferably, the cemented carbide insert has a bulk hardness of 1700 HV3 or less, or 1650 HV3 or less, or 1600 HV3 or less.

[0035] In one embodiment, the top of the insert has a higher surface hardness than the cylindrical portion and the bottom, but the bulk hardness is the same inside the insert.

[0036] Preferably, the binder phase comprises at least 80% by weight of one or more of cobalt, nickel, iron, or combinations thereof.

[0037] Preferably, the binder phase is Co and / or Ni, most preferably Co, even more preferably 3-20 wt % Co. Optionally, the binder is a nickel chromium or nickel aluminium alloy.

[0038] The carbide mining insert may further optionally include a grain refiner compound in an amount of ≦20 wt.% of the binder content. The grain refiner compound is suitably selected from the group of carbides, mixed carbides, carbonitrides, or nitrides of vanadium, chromium, tantalum, and niobium. The remainder of the carbide mining insert is made up of one or more hard phase components.

[0039] The binder content may be constant throughout the insert or may have a gradient from the surface to the bulk of the insert.

[0040] Preferably, the cubic precursor for the gamma phase is tantalum carbide or niobium carbide, or a mixture thereof, which is beneficial for resistance to plastic deformation at high temperatures.

[0041] Preferably, the amount of TaC+NbC is 0.8 to 10% by weight, or 1 to 8% by weight, or 1 to 5% by weight, or 1.2 to 5% by weight, or 1.2 to 3% by weight, or 1.5 to 6% by weight.

[0042] The weight ratio of Ta / Nb is preferably 0.1-100, more preferably 0.5-50, even more preferably 1-10, and most preferably 2-6.

[0043] Optionally, the cemented carbide further comprises Cr in an amount such that the mass ratio Cr / Co in the bulk is 0.04-0.19. Preferably, the mass ratio Cr / Co in the cemented carbide is 0.06-0.16, more preferably, the mass ratio Cr / Co in the cemented carbide is 0.07-0.15, and most preferably, the mass ratio Cr / Co in the cemented carbide is 0.075-0.12. Advantageously, the presence of chromium improves the plastic deformation of the cemented carbide, which can introduce higher compressive stresses into the carbides when the carbides are treated with surface high energy post-treatments such as tumbling or vigorous shaking. This increase in compressive stress improves the apparent hardness and thus the wear resistance of the cemented carbide, without reducing the toughness.

[0044] The Cr / binder mass ratio is calculated by dividing the weight percentage (wt%) of Cr added to the powder mix by the weight percentage of binder in the powder mix, where the weight percentage is based on the weight of that component compared to the total weight of the powder mix. Although Cr is largely dissolved in the binder phase, there may be some amount, e.g., up to 3 wt%, of undissolved chromium carbide in the cemented carbide body. However, it may be preferred to add only Cr up to the Cr / binder mass ratio so that all Cr is dissolved in the binder, such that the sintered cemented carbide body has no undissolved chromium carbide.

[0045] Cr is usually added to the powder mix in the form of Cr3C2 as this results in the highest percentage of Cr per gram of powder, however, alternative Cr 26 It is understood that chromium carbides or nitrides, such as CrC2 or Cr7C3, or chromium oxides may be added to the powder mixture used. The addition of Cr also has the effect of improving the corrosion resistance of the cemented carbide body. The presence of Cr also tends to transform the binder from fcc to hcp during drilling, which is beneficial in absorbing some of the energy generated in the drilling operation. The transformation thus hardens the binder phase and reduces the wear of the button during its use. The presence of Cr improves the wear resistance of the cemented carbide and improves its ability for deformation hardening. The combination of Cr in the cemented carbide powder and the application of a powder containing a grain refiner compound and, optionally, a carbon-based grain growth promoter to at least one portion of the surface of the compact results in a cemented carbide body with a chemical and hardness gradient, producing a cemented carbide mining insert with high wear resistance.

[0046] In one embodiment of the present invention, the cemented carbide is selected from the group consisting of M7C3 carbides and / or M 23 C6 carbides, and optionally M3C2 carbides, where M is Cr and optionally one or more of W, Co, and other elements added to the cemented carbide. Thereby, as used herein, M7C3 carbides and / or M 23It is meant that C6 carbides should be clearly visible in a SEM (Scanning Electron Microscope) image using backscattering at a magnification sufficient to detect particles of 100 nm size. In one embodiment of the invention, the cemented carbide is composed of carbides in a ratio of vol% (M7C3 carbides and / or M 23 M7C3 carbide and / or M in an amount given by vol%Co 23 Suitably, the proportion by vol.% (M7C3 carbides and / or M 23 M7C3 carbide and / or M 23 The vol% of C6 carbide and Co binder can be measured by EBSD or image analysis using appropriate software.

[0047] In one embodiment, the cemented carbide is free of eta phase and graphite. If the binder phase consists of cobalt, the cemented carbide is free of eta phase and graphite if the Com / Co ratio is 0.75≦Com / Co≦0.98. Metals used as binder phases in cemented carbides, such as Co, Ni, and Fe, are ferromagnetic. Saturation magnetization is the maximum possible magnetization of a ferromagnetic material characterized by the parallel orientation of all magnetic moments inside the material. A Forster KOERZIMAT 1.096 is used to determine the magnetic saturation (Com) dipole moment jS and the induced weight specific saturation magnetization σS (4πσ) of the insert. The Co content is then measured by XRF (X-ray fluorescence) using a Malvern Panalytical Axios Max Advanced instrument. The range of Com / %Co between eta phase and graphite formation can be influenced by changing the binder composition, such as by adding Cr, Fe, Ni, etc.

[0048] The solubility of W in the binder phase is directly related to the carbon content. The amount of W in the binder increases with decreasing carbon content until the limit for eta phase formation is reached. If the carbon content is decreased further lower, the solubility of W in the binder does not increase further. In some cemented carbide grades where it is beneficial to have a high amount of W dissolved in the binder, the carbon content is kept low but above the limit for eta phase formation.

[0049] In one embodiment, the fracture toughness difference between 0.5 mm below the surface and the bulk (ΔK1C) is at least 1.5, more preferably at least 1.8, even more preferably at least 2.0, and most preferably at least 2.2 MPa. * m 0.5 The fracture toughness K1C is measured using 5-10 Vickers indentations and a load of 30 kg and calculated using the Shetty formula:

[0050] Figure 1 shows the locations where the indentations were placed for ΔK1C and ΔHV3 measurements. On the left side of the split, polished sample HV30, the indentations were placed 0.5 mm from the surface 10 (unfilled diamonds) and in the bulk 20 (black diamonds). On the right side of the sample, HV3 was measured 0.3 mm from the surface 30 (black filled diamonds), 1 mm from the surface 40 (grey diamonds), and in the bulk 50 (light grey diamonds).

[0051] In one embodiment, there is a rock bit body including one or more attached cemented carbide inserts as described above or below.

[0052] According to one embodiment, the cemented carbide insert is mounted in a rock drill bit body of a tophammer (TH) or down-the-hole (DTH) drilling rig or rotary drilling rig or cutting disk rig. The rotary drilling rig may be an oil and gas rotary cutting rig. The invention also relates to a rock drill or cutting rig, in particular a tophammer rig or down-the-hole drilling rig or rotary drilling rig or cutting disk rig, and the use of the cemented carbide insert according to the invention in such rig.

[0053] Another aspect of the present disclosure relates to the use of a cemented carbide mining insert for rock drilling or oil and gas drilling, as described above or below.

[0054] Another aspect of the invention is a method for manufacturing a cemented carbide insert according to any one of claims 1 to 7, comprising the steps of: a) providing a green cemented carbide insert comprising 0.8-10 wt. % cubic carbides and / or carbonitrides and / or nitrides, 4-18 wt. % binder, any unavoidable impurities, and the balance WC hard phase; b) sintering the green carbide mining insert to form a sintered cemented carbide insert; c) subjecting the sintered cemented carbide insert to a high energy post-treatment; The method includes:

[0055] High energy aftertreatment (HET) is ΔHV3%≧9.72-00.00543 * HV3 bulk HET is considered to be a process in which homogeneous cemented carbide mining inserts are deformation hardened in a post-treatment such that ΔHV3% is the percentage difference between the HV3 measurement at 0.3 mm from the surface and the HV3 measurement in the bulk. HET can also be understood to mean a post-treatment process that causes a hardness difference between 0.3 mm from the surface and the bulk of at least 20 HV3. HET can also be understood to mean that there is an increase in both hardness and toughness that is caused from the surface to the bulk or in the bulk without changing the chemical composition or WC grain size near the surface (below 0.3 mm).

[0056] To introduce higher levels of compressive stresses into hard metal mining inserts, high energy shaking or tumbling processes may be used. There are a variety of possible process setups that can be used to introduce HET, including the type of equipment, the volume of added media (if any), processing time, and process setup, e.g., RPM for centrifugal tumblers or shaking equipment, etc. Thus, the most appropriate way to define HET is in terms of "any process setup that introduces a certain degree of deformation hardening in a homogenous hard metal mining insert consisting of WC-Co with a mass of about 20 g." In this disclosure, HET is defined as a post-treatment process that introduces a hardness change, measured using HV3 after at least the following post-treatment (ΔHV3%): ΔHV3%=9.72-0.00543 * HV3bulk (formula 1) where ΔHV3%=100 * (HV30.3mm-HV3bulk) / HV3bulk(Formula 2)

[0057] HV3 bulk is the average of at least 10 dent points measured at the innermost (center) part of the cemented carbide mining insert, HV3 0.3mm is the average of at least 10 dimple points 0.3 mm below the tumbled surface of the cemented carbide mining insert. This is based on measurements made on a cemented carbide mining insert with homogeneous properties. By "homogeneous properties" we mean that after sintering the hardness difference is 1% or less from the surface region to the bulk region. The HET parameters used to achieve the deformation hardening described in equations (1) and (2) on a homogeneous cemented carbide mining insert are applied to a cemented carbide body with gradient properties.

[0058] HET may be performed using centrifugal tumbling in an ERBA120, typically running at about 200 RPM if the tumbling operation is performed without media or with media larger in size than the insert being tumbled, at about 300 RPM if the media used is smaller in size than the insert being tumbled, using a Rosler tumbler with a disk size of about 350 mm, at about 280 RPM if the tumbling operation is performed without media or with media larger in size than the insert being tumbled, or at about 320 RPM if the media used is smaller in size than the insert being tumbled. Typically, the parts are tumbled for at least 40-80 minutes. A Corob™ Evoshake 500 commercial paint shaker with a maximum load of 40 kg and a maximum shaking frequency of 65 Hz is used to accommodate 600 rpm. One insert up to the maximum load of the insert machine is placed in a plastic sealed container, cylindrical or square in shape, optionally together with roughly spherical cemented carbide media of approximately 1200-1600 Vickers hardness, with the addition of a small amount of cooling liquid (antioxidants and water), not all of the insert is covered by the cooling liquid. The degree of filling in the plastic container is preferably 20-80% of the volume, most preferably 30-50% of the container volume. The container is shaken for 5-30 minutes, preferably 5-15 minutes, using 100% of the shaking capacity of the machine (600 rpm), which corresponds to or exceeds the compressive stress level that can be obtained with the ERBA120 using the above parameters. A smoother gradient step can be applied by lowering the rpm. This is beneficial if the insert has a tendency to break. During the shaking process, the insert and the cooling liquid are heated up to about 70-90 °C.

[0059] In one embodiment, the high energy post-treatment is performed at high temperatures at or above 100°C, preferably at or above 200°C, more preferably at temperatures between 200°C and 450°C. The advantage of the high treatment temperature is that it improves the toughness of the carbide, so that impacts do not result in defects such as microcracks, large cracks, or edge chipping. The higher level of compressive stress, coupled with the reduction in impact defects, improves the fatigue resistance and fracture toughness of the mining insert, thus improving the life of the insert. An additional advantage of this method is that insert geometries, such as those with sharp bottom radii, that were previously subject to excessive damage to corners and therefore low yields, can now be tumbled without causing edge damage. This opens the possibility to develop mining insert products with different geometries that were not previously suitable for HET. The method also allows the use of cemented carbide compositions that were previously too brittle for mining applications. The ability to introduce higher levels of compressive stress increases the toughness of the mining insert to an acceptable level, meaning that mining inserts with higher hardness can be used, which is beneficial for improving the wear resistance of the mining insert.

[0060] In one embodiment of the invention, the mining insert is subjected to a surface hardening treatment at a temperature of 150-250°C, preferably at a temperature of 175-225°C.

[0061] In one embodiment of the invention, the mining insert is subjected to a surface hardening treatment at a temperature of 300-600°C, preferably at a temperature of 350-550°C, more preferably at a temperature of 450-550°C.

[0062] The temperature is measured on the mining insert using any suitable method for measuring temperature, preferably an infrared temperature measuring device is used.

[0063] The effectiveness of the surface hardening treatment at elevated temperatures is enhanced if the process is performed in a dry state. By "dry" it is meant that no liquid is added to the process. Without being bound by theory, it is believed that if a liquid is introduced into the process, it keeps the parts at room temperature. Additionally, the inclusion of a liquid reduces the degree of impact between the parts being HET treated. The liquid prevents internal friction and the heat of impact which increases the temperature at the impact point. If no liquid is used, then the temperature at the impact point will likely result in a higher toughness of the material subjected to the impact point.

[0064] Alternatively, the tumbler can be pressurized to a pressure that prevents the water from boiling, so that it is possible to perform the high temperature HET process in a wet state.

[0065] The HET process can be performed with or without the presence of media, depending on the shape and material composition of the mining insert being tumbled. If a decision is made to add media, the type and ratio of media to the insert is selected to suit the shape and material composition of the mining insert being HET processed.

[0066] Optionally, all or a portion of the heat is generated by friction between the insert and any media added in the HET process.

[0067] In one embodiment, the insert can be heated in a separate step prior to the hardfacing process step. A number of methods can be used to produce high temperatures for the mining insert, such as using induction heating, resistance heating, hot air heating, flame heating, preheating on a hot surface in an oven or furnace, or laser heating.

[0068] In one embodiment, the mining insert is kept heated during the hardfacing process, for example using an induction coil.

[0069] In one embodiment, all or part of the heat is generated by friction between the insert and any media added in the HET process. Advantageously, this removes debris and oxides, such as iron oxide, that have built up on the insert face from inside the process vessel. A second surface hardening process, carried out at room temperature in wet conditions, can be carried out, which helps remove dirt and dust from the mining insert being treated, reducing health hazards.

[0070] In one embodiment, after the mining insert is subjected to a hardfacing process at elevated temperature, the mining insert is subjected to a second hardfacing process at room temperature.

[0071] In one embodiment, the second hardening process is high energy tumbling.

[0072] In one embodiment, the high energy post-treatment is carried out by a bidirectional shaking process.

[0073] In one embodiment, the major movement of the bidirectional shaking process is in the vertical direction and the minor movement is in the horizontal direction.

[0074] In one embodiment, the bidirectional shaking process is carried out at 400-700 rpm for 5-30 minutes, preferably 500-600 rpm, and preferably 5-15 minutes. EXAMPLES

[0075] Example 1 sample Table 1 provides an overview of the samples tested, including their compositions and surface hardening treatments. The WC content is the balance in the following examples. TIFF2024527394000003.tif142170

[0076] All the cemented carbide inserts were fabricated using WC powder particle size 2-18 μm measured as FSSS before grinding. The WC and Co powders were ball milled in wet condition using ethanol with the addition of 2 wt% polyethylene glycol (PEG3400) as an organic binder (compressing agent) and cemented carbide grinding bodies. After grinding, the mixture was spray dried in N2 atmosphere and then uniaxially pressed into GT7S100A mining inserts, each with a spherical dome ("cutting edge") at the apex, with an outer diameter (OD) of about 10 mm, a height of about 16-20 mm, and weighing approximately 17 g. The samples were then sintered using sinter-HIP at 1410 °C for 1 h at 55 bar Ar pressure and then ground on a cylindrical section.

[0077] The samples, which were HET, were processed using a Corob™ Evoshake500 commercial paint shaker with a maximum load of 40 kg and a maximum shaking frequency of 65 Hz (600 rpm). 20 inserts were placed in a poly bucket with height = 12 cm and OD = 10 cm together with 3 kg of 7 mm approximately spherical cemented carbide media with a Vickers hardness of 1600 and 1 dl of water with added antioxidants. The degree of filling was about 40%. The bucket was shaken for 5 minutes using 100% of the shaking capacity of the machine. Three smoother gradient steps were applied: 30 seconds at 25%, 30 seconds at 50%, and 30 seconds at 75% of the maximum shaking capacity. After 5 minutes at maximum frequency, the 10 inserts were removed ("5 min HET"), and then the same program was resumed for another 5 minutes at maximum frequency ("10 min HET").

[0078] Some inserts were treated at 300°C in a so-called "high temperature HET" treatment using a Corob™ Simple Shake 90 paint shaker with a maximum load of 40 kg and a maximum shaking frequency of 65 Hz (600 rpm). The high temperature shaking method was carried out at a frequency of 5 Hz. Approximately 800 grams or 50 inserts and 3.75 kg of carbide media (7 mm balls) were placed in a cylindrical steel container with an inner diameter of 10.4 cm and an inner height of 12.4 cm, filling 1 / 3 to 2 / 3 of the height, preferably approximately 1 / 2. The steel cylinder with the mining inserts was heated to a high temperature of 300°C with media in a furnace and the mining inserts were held at the target temperature for 120 minutes. After heating, the steel cylinder was transferred directly to the paint shaker and immediately shaken twice for 5 minutes using a program without ramping. The transfer time between the furnace and the starting shaker was less than 20 seconds. The media (7 mm balls) consisted of a cemented carbide grade with a sintered HV20 of about 1600. Shaking was performed dry, i.e., the samples were heated to 300° C. without adding water to the shaker. For all runs, the inserts were cooled to room temperature before subjecting them to two final wet shaking runs of 5 minutes each, using a poly bucket as described above. None of the inventive samples had any edge damage after the post-treatment process.

[0079] Example 2 Insert Compression Test The insert compression test method involves compressing a drilling bit insert between two flat parallel rigid counter faces at a constant rate of displacement until fracture of the insert. A test apparatus based on the ISO4506:2017(E) standard "Hard metals - Compression test" was used with Hyperion's cemented carbide anvil grade H6F, with a hardness of over 2000HV, while the test method is itself suitable for toughness testing of rock drilling inserts. The apparatus was fitted onto an Instron 5989 test frame.

[0080] The loading axis was identical to the axis of rotational symmetry of the insert. The counter faces of the device fulfilled the parallelism required in the ISO4506:2017(E) standard, i.e. a maximum deviation of 0.5 μm / mm. The inserts to be tested were loaded at a constant rate of crosshead displacement equal to 0.6 mm / min until fracture, while the load-displacement curves were recorded. The compliance of the test rig and the test device was subtracted from the measured load-displacement curves before the test evaluation. Three inserts were tested per run. The counter faces were examined for damage before each test. Insert fracture was defined as occurring when the measured load dropped suddenly by at least 1000 N. Subsequent inspection of the tested inserts confirmed that in all cases this coincided with the development of cracks visible to the naked eye. The material strength was characterized by the total absorbed deformation energy until fracture. The approximate fracture energy (Ec) required to fracture the samples is given in table 2 below in Joules (J). TIFF2024527394000004.tif97170

[0081] Example 3 hardness measurement The hardness of the cemented carbide inserts was measured using a Vickers 3kg hardness tester at both 0.3mm and 1.0mm from the surface of the insert as well as in the bulk of the insert. Hardness measurements are the average of 30 indentations. Table 3 provides a summary of the hardness measurements and Table 4 provides a summary of the ΔHV3 hardness values. TIFF2024527394000005.tif100170

[0082] Example 4 Abrasion Test The samples were tested in an abrasion test, where the sample tip is worn against the counter face of a rotating granite barrel in a rotary operation. The test parameters used were: 100 N load applied to each insert, granite barrel rpm about 190, barrel diameter in the range of 130-150 mm, and horizontal feed rate of 0.339 mm / rev. A large amount of barrel length (up to 300 mm) was used in each test to eliminate any significant effect of composition differences in the rock on the results. If large pieces originated from the barrel, this area was avoided, and therefore the length in some tests was shorter than 300 mm. The sliding distance, which varied with the difference in diameter and length of the rock parts that could be used, was approximately 330-460 m, and the mass loss versus sliding distance was approximately linear between the three samples of each grade tested. The samples were cooled by a continuous flow of water. The samples were carefully washed and weighed respectively prior to and after the test. The mass loss of three samples per material was evaluated and the sample volume loss for each of the materials tested was calculated from the measured mass loss and sample density and the results are shown in Table 5. TIFF2024527394000006.tif52170

[0083] Example 5 Fracture toughness Fracture toughness measurements were performed according to ISO / DIS28079 using a 30 kg load on 10 mm diameter spherical dome shaped specimens subjected to 5 min HET treatment. The specimens were split in half through the dome area, mounted in bakelite, polished with diamond paste, and the crack lengths and diameters of 10 dents 0.5 mm below the surface, uniformly distributed around the insert, were at least 0.75 mm apart. The dent diameters and crack lengths were measured using an optical microscope and 200X magnification. K1C for each dent was calculated using the Shetty formula K1C=A * Calculated using the square root (H) / (P / Sum of L), where H is the hardness in N / mm 2 where P is the applied load in N, L is the sum of the crack lengths in mm, A is a constant with a value of 0.0028, and K1C is in MPa * m 0.5The average K1C value calculated and reported as K1C surface, crack length, and diameter of five dents in the center of the 10 mm insert were measured and the average was calculated and reported as K1C bulk. The K1C measurements and ΔK1C values ​​are shown in Table 5. TIFF2024527394000007.tif37170

[0084] For untreated samples, ΔK1C is 0, close to 0, or slightly negative.

[0085] Example 6 Practical Exam 1 Table 6 shows the results of the wet earth tophammer application test. Inserts with diameters of 13 mm, 11 mm, and spherical dome shapes were tested. The inserts were manufactured as described in Example 1. The outer diameter of all inserts was ground. HET treatment of the inserts was performed as described in Example 1 and the inserts were not preheated.

[0086] The different grades and treatments were fitted to steel bits with eight 13 mm inserts on the perimeter / gauge and three 11 mm inserts on the front. The bits were tested in an underground gold mine in the north of Sweden in a tophammer application. The rock conditions were classified as very hard and very abrasive. Before drilling began, the maximum diameter of each bit was measured to be approximately 56 mm. Each bit was drilled until the inserts were too dull and penetration dropped. Afterwards, the maximum diameter of the bit was measured again and the difference in diameter was assessed as wear due to drilling. Another important factor that determines the success of the inserts is the number of insert breakages. The results for both wear and breakage are shown in Table 6. TIFF2024527394000008.tif86170

[0087] The results clearly show that the samples of the present invention have good wear resistance and no insert chipping or breakage, which is usually expected for a grade containing gamma phase in impact drilling operations. By combining the grade containing gamma phase with HET treatment, the maximum potential of the material can be utilized, and the performance is better than the prior art grade DP65™ in terms of resistance to chipping / insert breakage, yet with the same high wear resistance. The site is also seen to be difficult to drill, as the submicron (WC) and chromium-containing grade R completely fails after only 6.3 m of operation, and the prior art chromium-containing grade M wears more than the gamma phase-containing grade of the present invention.

[0088] Example 7 Practical Test 2 Table 7 shows the results of wet earth tophammer application testing of 8 mm diameter, 10 mm diameter, and semi-ballistic dome shaped inserts. The inserts were manufactured as described in Example 1. The outer diameter of all inserts was ground. HET treatment of the inserts was performed as described in Example 1, and the inventive samples were high temperature HET treated as described in Example 1.

[0089] The different grades and treatments were fitted with steel bits with six 10mm inserts on the perimeter / gauge and three 8mm inserts on the front. Four bits / variants were manufactured and tested at an underground construction site in Stockholm, Sweden in a tophammer application. The rock conditions were classified as hard and abrasive. Before drilling started, the maximum diameter of each bit was measured to be approximately 51mm. Drilling started and each bit was used until the inserts became too dull and the penetration dropped. A few metres were drilled, after which the penetration dropped, after which the maximum diameter of the bit was measured and the difference in diameters was calculated divided by the metres drilled, which gives a good measure of the wear resistance of the grade. No insert breakage was observed in this test. TIFF2024527394000009.tif46170

[0090] The results clearly show that the gamma phase containing Grade G (invention) has higher wear resistance than the current benchmark impact Grade A and can drill significantly longer before needing to be reground. Importantly, no insert failures occurred for the gamma phase containing high temperature HET treated inserts.

[0091] Example 8 Practical Test 3 Table 8 shows the results of the dry (air-cooled) surface tophammer application test. Ballistic dome shaped inserts with a diameter of 7 mm were tested. The inserts were manufactured as described in Example 1. The outer diameter of all inserts was ground. HET treatment of the inserts was performed as described in Example 1, and the inserts were not preheated.

[0092] The different grades and treatments were fitted to steel bits with six 7 mm inserts on the circumference / gauge. The two front inserts in this test did not contribute to the diameter wear, for all bits they were of the reference grade XT49 (sample B). The bits were tested in a quarry in the south-west of Sweden in a tophammer application. The rock conditions were classified as homogeneous but very hard and very abrasive with a quartz content of about 50%, generating a lot of heat during drilling. A rig with two hammers was used simultaneously, allowing a good comparison between the variants. Before drilling started, the maximum diameter of each bit was measured in three positions (D1, D2, D3) and was approximately 33 mm. Each bit was drilled until the inserts were significantly worn, but only two were drilled to the end of their life (when loss of penetration or insert breakage occurred). Figure 2 shows a tophammer bit with ballistic inserts with the diameter measurement points indicated.

[0093] The maximum diameter of the bit was then measured again on all three (if no fracture) locations and the difference in diameter was assessed as the wear due to drilling. Another important factor in determining the success of the insert is the number of insert breakages. Both wear and fracture results are shown in Table 8. TIFF2024527394000010.tif85170

[0094] The results clearly show that the inventive sample has both good wear resistance and no insert chipping or breakage, which are usually expected for gamma-phase containing grades in impact drilling operations, and the wear resistance of gamma-phase (γ)+Cr is even better than two high Cr containing grades with the same binder content and similar room temperature hardness (HV20). By combining the gamma-phase (γ)+Cr containing grade with HET processing, the full potential of the material can be utilized, and the wear resistance is significantly better than that of XT49, even though the prior art grade XT49™ has a lower Co content, which is beneficial in dry (air-cooled) drilling, since the generated heat is significantly higher than in water-cooled impact drilling.

[0095] Example 9 Practical Test 4 Table 9 shows the results of the dry (air-cooled) surface tophammer application test. 7 mm diameter inserts with ballistic dome shape were tested. The inserts were manufactured according to the description in Example 1 and inventive sample I, and have about 20 microns of gamma phase free zone after sintering, which wears down quickly during drilling or is ground off during OD grinding. The OD of all inserts is ground. HET treatment of the inserts was performed according to the description in Example 1, and the inserts were not preheated.

[0096] The different grades and treatments were fitted to steel bits with six 7mm inserts on the circumference / gauge. The two front inserts in this test did not contribute to the diameter wear, for all bits they were of the reference grade XT49 (sample B). The bits were tested in a quarry in the southwest of Sweden in a tophammer application. The rock conditions were classified as homogeneous but very hard and very abrasive with a quartz content of about 50% and generated a lot of heat during drilling. A rig with two hammers was used at the same time, allowing a good comparison between the variants. Before drilling started, the maximum diameter of each bit was measured in three positions (D1, D2, D3) and was approximately 33 mm. Each bit was drilled until the inserts were significantly worn. Afterwards, the maximum diameter of the bit was measured again on all three (if not fractured) positions and the difference in diameter was evaluated as the wear due to drilling. Another important factor that determines the success of the inserts is the number of insert breakages. Both wear and breakage results are shown in Table 9. TIFF2024527394000011.tif66170

[0097] The results show that the inventive Sample I has sufficient toughness and strength from the HET process to be used in percussion drilling applications in sensitive ballistic insert configurations, despite having a very high gamma phase content and further containing Ti and Nitrogen (Ti, Ta, Nb, W) (C, N). Additionally, Sample I showed improved wear resistance compared to the prior art grade XT49™ (Sample B), even though the XT49 has a lower Co content that is beneficial in dry (air-cooled) drilling, since the heat generated is significantly higher than in water-cooled percussion drilling.

Claims

1. 1. A sintered cemented carbide insert for mining or cutting applications, comprising: The average WC grain size is 0.8 to 18 μm; A binder phase with a weight of 4 to 18 wt.-%; 0.8-10 wt. % gamma phase of cubic gamma phase precursor; Any unavoidable impurities, and the balance WC, A sintered cemented carbide insert, the difference between the hardness at any point 0.3 mm from the surface of the insert and the hardness of the bulk is at least 25 HV3 when measured according to ISO EN6507 3:2005.

2. The insert of claim 1 , wherein the binder phase comprises at least 80% by weight of one or more of cobalt, nickel, iron, or combinations thereof.

3. 2. The insert of claim 1, wherein the cubic gamma phase precursor is tantalum carbide or niobium carbide, or a mixture thereof.

4. The insert of claim 1, wherein the cemented carbide further comprises Cr in an amount such that the mass ratio Cr / Co in the bulk is between 0.04 and 0.

19.

5. The cemented carbide is ７ C ３ Carbide and / or M ２３ C ６ Including carbides, the ratio vol% (M ７ C ３ Carbide and / or M ２３ C ６ 2. The insert according to claim 1, wherein vol% Co is 0.01-0.

5.

6. The ΔK1C fracture toughness 0.5 mm below the surface compared to the K1C in the bulk is at least 1.5 MPa, measured according to ISO / DIS28079. ＊ m ０．５ The insert of claim 1 .

7. A rock drilling bit body comprising one or more attached cemented carbide inserts according to any one of claims 1 to 6.

8. A method for manufacturing a cemented carbide insert according to any one of claims 1 to 6, comprising the steps of: a) providing a green cemented carbide insert comprising 0.8-10 wt. % cubic carbides and / or carbonitrides and / or nitrides, 4-18 wt. % binder, any unavoidable impurities and the balance WC hard phase; b) sintering the green carbide mining insert to form a sintered cemented carbide insert; c) subjecting the sintered cemented carbide insert to a high energy post-treatment process; A method comprising:

9. 9. The method of claim 8, wherein the high-energy post-treatment is high-energy tumbling.

10. 9. The method of claim 8, wherein the high energy post-treatment is carried out at an elevated temperature of 100° C. or higher.

11. 9. The method of claim 8, wherein the high energy post-treatment is carried out by a bidirectional shaking process.

12. 9. The method of claim 8, wherein the major movements are in a vertical direction and the minor movements are in a horizontal direction.

13. The method of claim 8, wherein the treatment is carried out at 400-700 rpm for 5-30 minutes.

Images