TUBULAR PORTION AND BODY COMPRISING A COATED TUBULAR

PORTION

Technical field

The present disclosure relates to a body comprising a coated tubular portion, and to a method for manufacturing a body comprising a coated tubular portion.

Background

Hard facing of metal parts in industry today is commonly produced using processes such as thermal spraying, plasma-spraying, laser blown powder and weld overlay. One class of the key alloys developed for hard- facing is cobalt-superalloys comprising CoCrW which has an outstanding balance of properties including high resistance to wear, galling, sticking, scratching, abrasion, cavitation, chemical corrosion, high heat loads, thermal shock, creep and impact damage. The aforementioned processes are melt processes, i.e. powder is melted and then solidified on the surface of a metal part to form a coating, which all produce coatings suffering from residual stress, cracking, delamination risk, gas porosity and general lack of microstructure control during freezing. A problem is that, as a result, cobalt- superalloy hard-facing is only industrially available as thin coatings (a few 100 microns) and is often brittle, defect-ridden and with sub-optimal properties.

Therefore, there exists a need in the industry today for improved methods for manufacturing hard facing metal parts.

Summary

It is an object to mitigate, alleviate or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination and solve at least the above mentioned problem. This and other objects, that will become apparent in the following, are accomplished by a method for manufacturing a body comprising a coated tubular portion according to a first aspect of the present disclosure. The method comprises the steps of providing a body comprising a tubular portion having an outer surface and/or an inner surface surrounding a tubular channel, wherein the body is a metal-based body; providing a metal-based sheet spiral formed of a CoCrW alloy; arranging the metal-based sheet spiral in contact with one circumference on the outer or the inner surface of the tubular portion, to form a coated tube assembly; arranging the coated tube assembly in a hot isostatic pressing (HIP) canister; removing gas from the HIP canister; subjecting the coated tube assembly to a hot isostatic pressing process, thereby forming a metallurgical bond between the tubular portion of the body and the metal-based sheet spiral such that the metal-based sheet spiral forms a coating on the tubular portion.

Hereby, a body comprising a coated tubular portion, wherein the body is a metal-based body and the coating comprises a CoCrW alloy, can be manufactured in an effective manner.

The inventive method has proven highly promising for producing a plurality of different components having a body comprising a coated tubular portion such as valves, gates, seats, wear rings, milling sleeves, nozzles, gearing, extruder barrels, anti-gall bearings, cutters, turbomachinery, landing gear, cyclones, expanders and reducers, glass plungers, rollers and furnace hardware.

Manufacturing a coating of a desired thickness, such as a relatively thick coating, wherein the coating comprises a CoCrW alloy, on a metalbased body is known in the art to be difficult. The metal-based sheet spiral may be considered to have a spring-like effect which advantageously allows for a relatively snug fit between the metalbased sheet spiral and the tubular portion. Thus the risk of the metal-based spiral moving to an undesirable position during manufacturing is decreased.

Herein, the term “spring-like effect” may be understood as a property of a spiral expanding after being mechanically compressed or compressing after being mechanically expanded. A spiral may for example be compressed by pressing the spiral by hand, using a clamp and/or using pliers. A spiral may for example be expanded by pulling the spiral by hand and/or using pliers. Expressed differently, the spring-like effect may be considered the property of the metal-based sheet spiral storing mechanical energy when being actively compressed or expanded and elastically deforming when not being actively compressed or expanded. It is thus understood that the metal-based sheet spiral may be elastically and/or plastically deformed.

The metallurgical bond between the tubular portion and the metalbased sheet spiral provides a bond of high strength and a ductile interface. Consequently, the coating of the tubular portion of the body is durably attached to the tubular portion and provides high resistance to flaking.

The inventor has surprisingly found that the coating may be joined to the tubular portion with good interdiffusion and substantially without voids, porosity or cracks.

Herein, the term “metallurgical bond” refers to a diffusion bond formed in the solid state, in which the principal bonding mechanism is interdiffusion of atoms across the interface. This means the body comprising a coated tubular portion comprises a tubular portion and a coating metallurgically bonded at an interface, and in that the atoms originating from the tubular portion can be found at the opposite side of the interface, and vice versa. This type of bond may also be referred to as a solid-state metallurgical bond.

The Hot Isostatic Pressing (HIPping) process typically involves subjecting a component, in this case the coated tube assembly, to both an elevated temperature and an isostatic gas pressure in a high pressure containment vessel, using for example argon as pressurizing gas. By using a HIPping process for manufacturing the body comprising a coated tubular portion the porosity in the structure of the bodies comprising a coated tubular portion can be further reduced and the density of the structure further increased. Thus, an advantage using HIPping is that the body comprising a coated tubular portion after the HIPping process step has a near-net shape, i.e. , the shape of the manufactured tube after the HIPping process step is the same, or almost, or sufficiently the same as the desired shape of the final body comprising a coated tubular portion. Hence, post-treatment of the tube related to re-shaping can be omitted or at least reduced compared to prior art methods. Moreover, and according to at least one example embodiment of the disclosure, during the HIPping process, portions or parts of the coated tube assembly are subjected to some lateral shearing. The lateral shearing may act as a surface treatment and remove any residual oxidation layers, or dirt, and thereby ensure a good metallurgical bonding.

The hot isostatic pressing process may involve subjecting the coated tube assembly to a uniaxial pressure, e.g., by using a hot isostatic pressing equipment and the simultaneous application of heat and pressure. Thus, the plurality of pieces of a wrought material bond metallurgically to each other at a temperature high enough to induce sintering and creep processes.

It should be noted that for, e.g., HIPping, traditionally a can or canister, such as a HIPping can, or a HIPping canister, is filled with a metal powder, prior to subjecting the powder-filled can to the hot pressing. Thus, the powder is hot pressed for a predetermined time at a predetermined pressure and a predetermined temperature, and is thus consolidated to the metal-based component. In the inventive method, instead utilizing a body comprising a tubular portion and a metal-based sheet spiral, the drawbacks of using, e.g., powder as a starting material for the manufacturing method, such as, e.g., low packing density and the resulting shape change of the final product, are overcome, or at least reduced. Hence, the method according to the disclosure may be described as a metal powder-free hot pressing (or HIPping) manufacturing method for manufacturing a body comprising a coated tubular portion.

The inventive process is a solid-state, non-melt process which advantageously allows for the coating to retain the material properties of the provided metal-based sheet spiral. Thus the produced coating may be uniform, substantially pore-free, and have high hardness, good ductility and high toughness.

The inventive process allows for tailoring the thickness of the coating by e.g. providing a metal-based sheet spiral having a desirable thickness and/or providing a metal-based sheet spiral having a desirable amount of laps. Thus the inventive method is advantageous in that tailored products with tailored properties can be manufactured.

As referred to herein the term “tubular portion” generally refers either to a tube-like elongated hollow body, e.g. a body having a side wall surrounding an interior volume defined by the side wall, or a hole portion extending through a body. The hole portion is defined by an inner wall of the body, wherein the inner wall surrounds an interior volume. The interior volume may e.g. be a bore. The tubular portion may, e.g., have a substantially circular circumference or a substantiantially ellipsoidal circumference. The tubular portion may also have a conical shape.

As referred to herein the term “CoCrW alloy” generally refers to an alloy comprising Co, Cr, W, C and at least one optional additional alloying element such as Ni, Si, Fe, Mn, Mo. The CoCrW alloy may additionally comprise naturally occuring impurities. The CoCrW alloy may comprise naturally occuring impurities at a content of, by weight, 0-4 %, such as 0.2-3 %, such as 0.2-2 %.

As referred to herein the term “coated tube assembly” generally refers to an assembly comprising the tubular portion and the metal-based sheet spiral. It is understood that the coated tube assembly does not necessarily have the shape of a tube or a hollow cylinder. In some embodiments, the method comprises providing two or more metal-based spirals formed of a CoCrW alloy; arranging one metal-based sheet spiral in contact with a circumference on the outer surface of the tubular portion and one metal-based sheet spiral in contact with the inner surface of the tubular portion. This is advantageous as it allows for manufacturing a body comprising a coated tubular portion wherein the coated tubular portion is coated on both an outer surface and on an inner surface surrounding a tubular channel, simultaneously.

In some embodiments, the metal-based sheet spiral is wound at least one lap, such as at least one and a half laps, such as at least two laps, such as at least two and a half laps, such as at least three laps around a longitudinal axis of the spiral. The specific laps advantageously allow for an improved contact area of the metal-based sheet spiral to itself during the manufacturing process and an improved spring-effect. The number of laps advantageously allows for tailoring the thickness of the produced coating.

It is understood that the metal-based sheet spiral is bonded to itself during the manufacturing process described herein. Thus, the specified laps of the the metal-based sheet spiral may increase the contact area between portions of the metal-based sheet spiral which allows for a larger bonding portion between the portions of the metal-based sheet spiral.

In some embodiments, the hot isostatic process is conducted at a predetermined time, a predetermined pressure, and/or a predetermined temperature. Herein, the predetermined pressure, the predetermined time and the predetermined temperature used during the hot isostatic pressing process may be within the ranges of what is normally used within the hot isostatic pressing industry. The predetermined time, the predetermined pressure and the predetermined temperature may all vary due to a variety of parameters known to the skilled person. For example, they may vary due to the size or the shape of the metal-based tube which is being manufactured. Further, they may vary due to the material choice, e.g., which metal is being used. In some embodiments, the hot isostatic pressing process is conducted for a predetermined time in the range of 1-10 hours, at a predetermined pressure in the range of 50-250 MPa, and/or at a predetermined temperature in the range of 700-1600 °C. The specific predetermined time, predetermined pressure, and predetermined temperature have been found to be suitable for forming a body comprising a coated tubular portion exhibiting desirable properties such as high bond strength, high uniformity and low porosity. Typically, the predetermined pressure is in the range of 50-250 MPa, such as 70-230 MPa, such as 90-210 MPa. Typically, the predetermined temperature is in the range of 700-1600 °C, such as 900-1400 °C, such as 1000-1300 °C.

In some embodiments, the coating has a thickness in the range of from 0.3 to 10 mm, such as from 0.5 to 10 mm, such as from 1 to 10 mm, such as from 1 to 9 mm, such as from 2 to 8 mm. A coating of said thicknesses assures sufficient properties such as resistance to scratches and physical impacts meaning that the coating is resistant to penetration or wear.

In some embodiments, the method further comprises steps of providing a metal-based sheet; and bending the metal-based sheet to form the metal-based sheet spiral.

The step of bending the metal-based sheet to form the metal-based sheet spiral alters the microstructure of the provided metal-based sheet such that the grain size is decreased which advantageously increases the hardness and the toughness of the formed metal-based sheet spiral. Thus, the metal-based sheet may form a coating having increased hardness and toughness.

In some embodiments, the method comprises a step of polishing at least one side of the sheet to form a polished sheet.

The polishing may be performed in a series of iterations using finer and finer abrasives to provide a clean and/or near mirror-like polish. The polishing may remove dirt and unwanted oxides which may be present on an unpolished sheet. In one example, the polishing is performed using an angle grinder. In some embodiments, the step of bending is performed by mechanical rollers. In some embodiments, the step of bending is performed at a temperature in the range of from room temperature to 200 °C. The specified temperature has been found particularly suitable for performing bending.

The term “room temperature” as referred to herein, may generally be understood as a temperature of 15-30 °C.

As an alternative, the step of bending may be performed at a temperature in the range of 5-200 °C, such as from 10-200 °C, such as from 15-200 °C, such as from 18.5-200°C, such as from 20-180 °C, such as from 20-170 °C.

In some embodiments, the metal-based sheet has a thickness in the range of from 0.3 to 3 mm, such as from 0.3 to 2.5 mm, such as from 0.4 to 2.5 mm, such as from 0.4 to 2 mm, such as from 0.4 to 1 .5 mm. In some embodiments, the thickness is less than 1 mm. The thickness advantageously allows for tailoring the formed coating on the tubular portion. The specified thickness provides a metal-based sheet particularly suitable for bending.

In some embodiments, an outer diameter of the metal-based sheet spiral is at least one of larger than an inner diameter of the tubular portion of the body or smaller than an outer diameter of the tubular portion of the body.

The specified diameters advantageously improves the spring-effect of the metal-based sheet spiral when it is arranged in contact with one circumference of the outer or the inner surface of the tubular portion.

An outer diameter of the metal-based sheet spiral larger than an inner diameter of the tubular portion of the body is particularly useful when the metal-based sheet spiral is arranged in contact with one circumference of the inner surface of the tubular portion. The metal-based sheet spiral could thus be compressed prior to being arranged in contact with one circumference of the inner surface of the tubular portion. Thus, the metal-based sheet spiral when released from active compression expands so as to exhibit a spring-like effect and is mechanically pressed against the circumference of the inner surface of the tubular portion.

An outer diameter of the metal-based sheet spiral smaller than an outer diameter of the tubular portion of the body is particularly useful when the metal-based sheet spiral is being arranged in contact with one circumference of the outer surface of the tubular portion. The metal-based sheet spiral could thus be expanded to be arranged in contact with one circumference of the outer surface of the tubular portion. Thus, the metalbased sheet spiral when released from active expansion contracts so as to exhibit a spring-like effect and is mechanically pressed against the circumference of the outer surface of the tubular portion.

In some embodiments, the body is formed of an alloy being selected from the list of steel, stainless steel, Ni-based alloys, Ti-based alloys and Cu- based alloys. The inventors have surprisingly found that a coating comprising a CoCrW alloy as described herein can be arranged on and metallurgically bonded to a tubular portion of a body formed of an alloy being selected from the list of steel, stainless steel, Ni-based alloys, Ti-based alloys and Cu-based alloys.

The term “body is formed of an alloy being selected from the list of steel, stainless steel, Ni-based alloys, Ti-based alloys and Cu-based alloys” refers to that the body should comprise a major portion (by weight) of said alloy, such as at least 60 %, such as at least 70 %, such as at least 80 %, such as at least 80 %, such as at least 90 %, such as at least 95 %. The body may in some examples consist of an alloy being selected from the list of steel, stainless steel, Ni-based alloys, Ti-based alloys and Cu-based alloys.

The terms “steel” and “stainless steel” are known to the person skilled in the art.

The term “Ni-based alloys” is known to the person skilled in the art. A Ni-based alloy, also referred to as a Nickel-based alloy, comprises mainly nickel and at least one other alloying element such as Cr, Co, Cb, Mo, Mn, Al, Si, W, Nb. The term “Ti-based alloys” is known to the person skilled in the art. A Ti-based alloy, also referred to as a Titanium-based alloy, comprises mainly Titanium and at least one other alloying element such as Al, V, Sn, Pd, Mb, Ni, Ru, Zr.

The term “Cu-based alloys” is known to the person skilled in the art. A Cu-based alloy, also referred to as a Copper-based alloy, comprises mainly Copper and at least one other alloying element, such as Zn, Sn, Al, Si, Ni, Be, Cr, Zr.

In some embodiments, the method further comprises a step of subjecting the body comprising the coated tubular portion to a heat treatment. The heat treatment may be selected from solution annealing, quenching and tempering. Subjecting the body comprising the coated tubular portion to a heat treatment can be performed to alter the physical and/or chemical properties of the body comprising a coated tubular portion such as increasing ductility, reducing hardness, increasing toughness, and preventing undesirable low-temperature processes.

In some embodiments, the method further comprises a step of removing material from the body comprising the coated tubular portion using lathing, milling, or drilling. By removing material from the body comprising a coated tubular portion the shape can be even further tailored after the hot isostatic pressing process.

In some embodiments, the metal-based sheet spiral has an archimedean spiral shape, a circular shape, an involute shape, a conical shape, a 3D helix shape, or a square shape. The specified shapes have been proven suitable in the inventive manufacturing process. The shape may be chosen depending on the desired properties of the produced coating, thereby allowing for the manufacture of a tailored product.

In some embodiments, the method further comprises steps of providing at least one second metal-based sheet spiral; stacking the metal-based sheet spiral and the at least one second metal-based sheet spiral concentrically or vertically to form a stacked spiral assembly; and arranging the stacked spiral assembly in contact with one circumference on the outer or the inner surface of the tubular portion, to form a coated tube assembly.

Stacking the metal-based sheet spiral and the at least one second metal-based sheet spiral concentrically or vertically advantageously allows for further tailoring of the dimensions, thickness and extension of the coating. It is understood that the at least one spiral and at least one of the at least one second spiral are bonded during the HIPping process.

It is understood that a combination of stacking metal-based sheet spirals concentrically and vertically may be utilised within the present inventive concept.

In some embodiments, the CoCrW alloy comprises, in wt%, Cr 28-32,

W 3.5-5.5,

C 0.5-2.0,

Ni 0-3,

Si 0-2,

Fe 0-3,

Mn 0-2 and

Mo 0-1.5; the balance being Co and naturally occuring impurities.

The specified alloys are known in the art to be limited to the coating techniques of thermal spraying, plasma-spraying, laser blown powder and weld overlay to provide a coating on a metal-based body, e.g. a metal-based body formed of steel, stainless steel, Ni-based alloys, Ti-based alloys and Cu- based alloys when applied as a coating to a metal-based body. Thus, the specific alloys have previously only been industrially available as a thin coating, e.g. coating having a thickness of below 100 pm, on a metal-based body. Attempts of e.g. thicker coatings of the specific alloys, using e.g. coating techniques mentioned above, have proven to suffer from residual stress, cracking, delamination risk, gas porosity and general lack of microstructure contrail during freezing.

The CoCrW alloy is preferably providable in sheet form, such as a relatively thin sheet. Examples of such CoCrW alloys are the commercially available materials Stellite™ 6B and Stellite™ 6K.

The inventor has surprisingly found that the specific alloys may be used in the inventive process so as to form a coated tubular portion of desired thickness while showing desirable material properties.

According to a second aspect of the disclosure, there is provided a body comprising a coated tubular portion having a metal-based body comprising a tubular portion having an outer surface and/or an inner surface surrounding a tubular channel; a coating formed of a CoCrW alloy, arranged on the outer surface or the inner surface of the tubular portion; the body comprises a metallurgical bond at an interface between the tubular portion and the coating; and the body comprises traces at the interface between the tubular portion and the coating, wherein said traces are formed by crystallographic mismatch.

It is understood that some of the advantages discussed in relation to the first aspect also apply to the second aspect.

In some embodiments, the metallurgical bond is formed by a hot isostatic pressing process.

The traces formed by crystallographic mismatch stem/originate from the hot isostatic pressing process. The interface between the tubular portion and the coating may be traced as it appears as a line, along which line metal grains are arranged. The line typically extends along the full length of the interface between the surface(s) of the tubular portion and the coating in contact with each other. The traces are formed by crystallographic mismatch between the metal grains in the tubular portion and the coating at the interface at the metallurgical bond. These traces can be seen in an etched sample of the final product, thereby acting as a fingerprint indicating that the body has been manufactured according to the hot isostatic pressing process.

Traces will be visible in any cross-section perpendicular to the lengthwise extension of the tubular portion taken along the length of the tubular portion, owing to the fact that lateral surfaces of the tubular portion and the coating are metallurgically bonded together.

In some examples, the body comprises more than one tubular portion, such as two bores, three bores, or four bores.

The inventors have found that the coating is substantially uniform and pore-free, and exhibits high hardness, good ductility and high toughness.

A cross-section of the body may for example have a square shape, rectangular shape, ellipsoidal shape, circular shape or a hexagonal shape.

In some embodiments, the coating is formed of a metal-based sheet spiral.

In some embodiments, an interface between the tubular portion and the coating comprises a ridge. The ridge may be considered a fingerprint indicating that the body comprising a coated tubular portion has been manufactured using, for the coating, a metal-based sheet spiral and, for bonding the coating to the body, the hot isostatic pressing process. Further, the ridge indicates that the coating has been pressed into the tubular portion, indicating a strong bond.

In some embodiments, the coating has a hardness of at least 500 HV. The hardness of the coating is surprisingly high and allows for a body comprising a coated tubular portion having desirable material properties.

In some embodiments, the coating has a minimum thickness in the range of from 0.3 to 10 mm, such as from 0.5 to 10 mm, such as from 1 to 10 mm, such as from 1 to 9 mm, such as from 2 to 8 mm. A coating of said thicknesses assures sufficient properties such as resistance to scratches and physical impacts meaning that the coating is not penetrated or worn down. In some embodiments, the coating is arranged so that it covers the outer surface or the inner surface of the tubular portion. A coating arranged so that it covers the outer or the inner surface provides the tubular portion with a wear resistant protection layer. In some embodiments, the coating may be arranged to cover the outer surface and the inner surface of the tubular portion.

In some embodiments, the coating comprises traces at an interface between a first portion of the coating and a second portion of the coating, wherein the traces are formed by crystallographic mismatch. Expressed differently, the traces may be provided at the interface between different portions of the coating. For example, a first portion of the coating may correspond to a first lap of a metal-based sheet spiral, and the second portion may correspond to a second lap of the metal-based sheet spiral, both wound such to provide a coating arranged on the outer surface or the inner surface of the tubular portion. In some embodiments, the coating is formed by a stacked spiral assembly as disclosed herein, and the coating comprises traces at an interface between different metal-based sheet spirals of the stacked spiral assembly. In a further example, the first and second portions of the coating may correspond to overlapping ends of a metal-based sheet spiral forming the coating.

These traces originate from the hot isostatic pressing process. The traces will be visible in any cross-section perpendicular to the lengthwise extension of the tubular portion taken along the length of the tubular portion, owing to the fact that lateral surfaces of the coating are metallurgically bonded together.

In some embodiments, the body comprises a coating formed of a CoCrW alloy, arranged on the outer surface and the inner surface of the tubular portion. Thus the body may advantageously be provided with a coating on, e.g., two surfaces. In some embodiments, the body comprises traces at an interface between a first portion of the coating and a second portion of the coating, wherein said traces are formed by crystallographic mismatch.

Effects and features of the second aspect are largely analogous to those described above in connection with the first aspect. Embodiments mentioned in relation to the first aspect are largely compatible with the second aspect. It is further noted that the inventive concepts relate to all possible combinations of features unless explicitly stated otherwise.

A further scope of applicability of the present disclosure will become apparent from the detailed description given below. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the scope of the disclosure will become apparent to those skilled in the art from this detailed description.

Hence, it is to be understood that this disclosure is not limited to the particular component parts of the device described or steps of the methods described as such device and method may vary. It is also to be understood that the terminology used herein is for purpose of describing particular embodiments only and is not intended to be limiting. It must be noted that, as used in the specification and the appended claim, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements unless the context clearly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may include several devices, and the like. Furthermore, the words "comprising", "including", "containing" and similar wordings does not exclude other elements or steps.

Brief description of the drawings

The above objects, as well as additional objects, features, and advantages of the present disclosure, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of embodiments of the present disclosure, when taken in conjunction with the accompanying drawings, wherein:

Fig. 1a-e shows, in cross section, schematic drawings of a body comprising one or more coated tubular portions according to embodiments of the disclosure;

Fig. 2 schematically shows a portion of a body comprising a coated tubular portion according to an embodiment of the disclosure;

Fig. 3 schematically shows a crystallographic mismatch located at the interface between the tubular portion and the coating according to an embodiment of the disclosure;

Fig. 4 shows a flow-sheet explaining the steps of a method in accordance with embodiments of the disclosure;

Fig. 5 shows a scanning electron micrograph of the metallurgical bond of the body between the tubular portion and the metal-based sheet spiral in accordance with an embodiment of the disclosure;

Fig. 6 shows an optical micrograph of the metallurgical bond of the body between the tubular portion and the metal-based sheet spiral in accordance with an embedment of the disclosure; and

Fig. 7 shows a hardness test result of a coating according to an embodiment of the disclosure.

Fig. 8 shows an optical micrograph of the metallurgical bond of the body between a first portion and a second portion of the coating in accordance with an embodiment of the disclosure.

The figures are not necessarily to scale, and generally only show parts that are necessary in order to elucidate the inventive concept, wherein other parts may be omitted or merely suggested.

Detailed description

Aspects and embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings. Figs. 1a-e depict bodies 100a, 100b, 100c, 100d, 100e comprising a coated tubular portion having a metal-based body 101 comprising a tubular portion having an outer surface 104 and/or an inner surface 105 surrounding a tubular channel. A coating 102 formed of a CoCrW alloy is arranged on the outer surface 104 or the inner surface 105 of the tubular portion. The body comprises a metallurgical bond at an interface between the tubular portion and the coating 102, wherein the metallurgical bond is formed by a hot isostatic pressing process.

The coating 102 may be arranged on the inner surface 105 of the tubular portion, as depicted in figures 1a, 1c, 1d and 1e.

The coating 102 may be arranged on the outer surface 104 of the tubular portion, as depicted in figures 1 b, 1c.

A coating 102 may be arranged on the outer surface 104 of the tubular portion and on the inner surface 105 of the tubular portion, as depicted in figure 1c.

As depicted in figure 1 e, the body may comprise a plurality of coated tubular portions. It is understood that the body may comprise a plurality of tubular portions wherein at least one of the tubular portions are coated.

The body comprising a coated tubular portion may in some embodiments be considered a tube or hollow cylinder. In some examples, the body comprising a coated tubular portion has a rectangular cross section, as depicted in figures 1d and 1e. The tubular portion may be a through hole.

As depicted in figure 2, an interface between the tubular portion and the coating 202 may comprise a ridge 204. The ridge 204 acts as a fingerprint indicating that the body 201 comprising a tubular portion has been manufactued using the hot isostatic pressing process. Further, the ridge 204 indicates that the coating 202 has been pressed into the tubular portion. Expressed differently, the coating 202 may be considered to protrude into the body 201 so as to form a ledge in the body 201 .

In some embodiments, the coating 102, 202 has a hardness of at least 500 HV. The hardness of the coating 102, 202 is surprisingly high and allows for a body comprising a coated tubular portion which has desirable material properties.

The coating 102, 202 may have a minimum thickness in the range of from 0.3 to 10 mm, such as from 0.5 to 10 mm, such as from 1 to 10 mm, such as from 1 to 9 mm, such as from 2 to 8 mm. A coating 102, 202 of said thicknesses assures sufficient properties such as resistance to scratches and physical impacts meaning that the coating 102, 202 is not penetrated or worn down.

The coating 102, 202 may be arranged so that it covers the outer surface 104 or the inner surface 105 of the tubular portion. A coating 102, 202 arranged so that it covers the outer or the inner surface provides the tubular portion with a wear resistant protection layer.

The body may comprise traces at the interface between the tubular portion and the coating, wherein said traces are formed by crystallographic mismatch. Figure 3 depicts a schematic image of a crystallographic mismatch located at the interface 303 between the tubular portion 301 and the coating 302. The trace, e.g., a metallurgical detectable trace, of the interface 303 between the coating 302 and the tubular portion 301 , is visible in the body 300 comprising a coated tubular portion 301 after it is manufactured by the hot isostatic pressing process. In the schematic, a line 305 is shown, along which a crystallographic mismatch of metal grains 380, 380’ is clearly visible, which line and crystallographic mismatch forms the trace. Thus, the traces are formed by crystallographic mismatch at the interface 303 between the tubular body 301 and the coating 302. Herein, the crystallographic mismatch is indicative of a metallurgical bond having been formed by a hot isostatic pressing process.

Figure 4 shows a flow-sheet describing different steps of a method for manufacturing a body comprising a coated tubular portion. The method 400 comprises: providing 401 a body comprising a tubular portion having an outer surface and/or an inner surface surrounding a tubular channel, wherein the body is a metal-based body; providing 402 a metal-based sheet spiral formed of a CoCrW alloy; arranging 403 the metal-based sheet spiral in contact with one circumference on the outer or the inner surface of the tubular portion, to form a coated tube assembly; arranging 404 the coated tube assembly in a hot isostatic pressing (HIP) canister; removing 405 gas from the HIP canister; subjecting 406 the coated tube assembly to a hot isostatic pressing process, thereby forming a metallurgical bond between the tubular portion of the body and the metal-based sheet spiral such that the metal-based sheet spiral forms a coating on the tubular portion.

The bodies comprising a coated tubular portion may be manufactured using the process described in relation to figure 4.

In providing 401 a body comprising a tubular portion having an outer surface and/or an inner surface surrounding a tubular channel, the body comprising a tubular portion may for example be a hollow cylinder or a body comprising an aperture or a through-hole, such as a bore. The tubular portion may have at least one opening in which the metal-based sheet spiral may be arranged so as to be in contact with a circumference on the inner surface of the tubular portion. Alternatively, or additionaly, the tubular portion should be provided such that the metal-based sheet spiral may be arranged so as to be in contact with a circumference on the outer surface of the tubular portion.

In providing 402 a metal-based sheet spiral formed of a CoCrW alloy, there is provided an element that can be in contact with a circumference on the outer or the inner surface of the tubular portion.

In arranging 403 the metal-based sheet spiral in contact with a circumference on the outer or the inner surface of the tubular portion, to form a coated tube assembly, the metal-based sheet spiral is positioned to be in contact with a circumference on the outer or the inner surface of the tubular portion, to form a coated tube assembly.

In one example where the metal-based sheet spiral is arranged in contact with a circumference on the outer or the inner surface of the tubular portion, the metal-based sheet spiral is wrapped around the outer surface so as to envelop the outer surface. In another example, the metal-based sheet spiral is positioned such that the tubular portion envelops the metal-based sheet spiral. An inner surface of the coated tubular portion may, according to this exemplifying embodiment, enclose a volume which volume will correspond to an interior channel of the manufactured body comprising a coated tubular portion.

In arranging 404 the coated tube assembly in a hot isostatic pressing (HIP) canister, the coated tube assembly is positioned in a canister which may be perimetrically sealed.

In removing 405 gas from the HIP canister, the contact between the tubular portion and the metal-based sheet spiral is improved. Gas may preferably be removed via a crimp tube. A good contact between the tubular portion and the metal-based sheet spiral is advantageous in that it improves the metallurgical bond formed during the subsequent hot isostatic pressing process.

In subjecting 406 the coated tube assembly to a hot isostatic pressing process, thereby forming a metallurgical bond between the tubular portion of the body and the metal-based sheet spiral such that the metal-based sheet spiral forms a coating on the tubular portion, the hot isostatic pressing process may be conducted for a predetermined time in the range of 1-10 hours, at a predetermined pressure in the range of 50-250 MPa, and/or at a predetermined temperature in the range of 700-1600 °C.

Examples

Manufacture

A test article comprising a tubular body of an austenitic nickelchromium based superalloy with an outer coating comprising a CoCrW alloy was produced using hot isostatic pressing. In the present example, the CoCrW alloy had a composition as shown in table 1 .

The test article was manufactured by arranging a metal-based sheet spiral having a composition as described in table 1 , in contact with a circumference on the outer surface of the tubular body, to form a coated tube assembly. The coated tube assembly was arranged in a HIPping canister and subjected to a hot isostatic pressing process to form a body comprising a coated tubular portion which in this example may be understood as a coated tubular body. A Scanning Electron Microscopy (SEM) image of the interface between the tubular body and the coating is shown in figure 5, showing a well-bonded interface with the CoCrW alloy at the bottom of the image and the austenitic nickel-chromium based superalloy at the top of the image.

Figure 6 shows an optical micrograph of another part of the interface wherein said interface comprises a ridge. The ridge was formed during the hot isostatic pressing process where the metal-based sheet spiral comprising the CoCrW alloy, to the right in the image, has been pressed into the tubular body, to the left in the image.

Figure 8 shows a image of the interface between a first portion (on the left of the image) of the coating and a second portion (on the right of the image) of the coating indicating a well-bonded interface. Said traces are formed by crystallographic mismatch. It is understood that the depicted interface is a result from at least partial overlap of the metal-based sheet spiral prior to the HIPping process.

Table 1 : Composition of example CoCrW alloy in wt%

Vickers hardness

The hardness of the coating was evaluted by means of a Vickers test, as shown in figure 7. The coating showed a hardness of 564 HV.

Without wishing to be bound by any particular theory, the inventor believes that the elevated hardness of the coating is due to the workhardening occuring when bending a metal-based sheet into a metal-based sheet spiral. It is concluded that the metal-based sheet spiral retains its hardness after HIPping, thus producing a body having a hard coating.

The person skilled in the art realizes that the present disclosure by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

For example, the tubular portion may have other shapes than that shown in the figures, such as for example ellipsoid, conical, or square. The metal-based sheet spiral may, accordingly, have the corresponding shapes.

Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed disclosure, from a study of the drawings, the disclosure, and the appended claims.