WO2014033479A1

WO2014033479A1 - Method and apparatus for continuous cladding

Info

Publication number: WO2014033479A1
Application number: PCT/GB2013/052299
Authority: WO
Inventors: Dorival Tecco
Original assignee: Welding Alloys Ltd
Current assignee: Welding Alloys Ltd
Priority date: 2012-08-31
Filing date: 2013-09-02
Publication date: 2014-03-06
Anticipated expiration: 2015-02-28
Also published as: GB201215506D0

Description

Method and apparatus for continuous cladding

The present invention relates to an apparatus and method for cladding and hardfacing and specifically, but not exclusively for the cladding and hardfacing of of flat products, and for cladding, hardfacing of products with polygonal or rounded cross sections.

In particular, the present invention relates to metallic components and use of electroslag welding, as well as welding processes that operate under inert or active gas atmospheres (examples of which are electro-gas welding, metal-inert gas welding and tungsten inert gas welding), without the problems of entrapment or contamination of inadequate slags, continuous casting methods or other methods involving continuous pouring of liquid metal. Throughout this specification the word "manufacture" is used in respect of not only the continuous cladding of new products but also the refurbishment of such products.

Currently, components and consumable products are manufactured for use in harsh and demanding working environments where resistance to abrasion, adhesion, erosion, cavitation, oxidation and/or corrosion is important and which comprise a metallic base or substrate that is welded on one or more of its surfaces. Such a substrate may be a steel, low-alloy ferrous material, iron or high-alloy ferrous material, cobalt-based alloy, nickel-based alloy or a copper- based alloy.

The manufacturing method may vary according to the product shape. In the case of flat plates, a common method involves the deposition of beads to achieve complete or partial coverage of one or two surfaces, such as described in (Browne et al, 1994) and (Rossner et al, 1965). In these cases, individual beads are laid along the length of the plate, until coverage is complete. A variation of this method is shown in (Miller, 1985), in which individual beads are deposited on a plate surface along its width, until the required coverage is achieved. By their nature, these methods are discontinuous because they need to be interrupted every time the welding gun reaches the edge of the plate, before it is re-positioned for the next bead; this limits the duty cycle, and reduces productivity. A further complication arises from the fact that the overlap region between two beads is a point of weakness as it is a preferential site for weld defects, and also a source of surface waviness/roughness.

Another common method to clad plates involves shaping the flat plate into a roll and rotating it continuously (Scandella et al, 2005). This is similar to the usual method of roll cladding, as described in (Arnoldy, 1980), (Jackson, 1999), (Tecco et al, 2007). This method has the advantage of welding continuously, however it does not solve the problem of many bead intersections with their associated problems.

A third variation of the manufacturing methods is described in (Paton et al, 1975), by attaching a mould to the edge of a plate-like product and laying a volume of hardfacing material with an electroslag welding process. In this way, a high quality, single deposit is produced, without the weak intersections between beads and with potential to produce improved surface roughness. However, the method is unsuitable for continuous production as it requires re-positioning the mould for each new plate or product.

Several proposals exist to clad cylindrical rolls, including for example centrifugal casting (Khandros, 1982), vertical spin casting (Iversen, 1989) and electroslag (Medovar, 2001 ). From the present standpoint, it is believed that these methods are limited because they involve large quantities of liquid metal, with inherent operational risks, high energetic demand, high cost and likelihood of segregation. Another undesirable consequence of the relatively large scale is the difficulty to produce thin cladded layers, which is an important requirement from the point of views of industrial demands and also limiting the costs of production. For instance, industries demand hardfaced plates as a consumable to combat abrasion with a steel base of 5mm thickness and hardfaced layer of 3mm thickness. Another example is the demand by steel industry for continuous casting rolls with a total clad layer with 6mm thickness or less. It is an object of the present invention to provide an apparatus and method for cladding and hardfacing products which addresses the abovementioned disadvantages of conventional apparatuses and methods.

Accordingly, in a first aspect, there is provided a method for cladding a substrate using a process zone the method comprising:

controlling the properties of the process zone;

passing the substrate in proximity to the process zone such that material of the process zone dads the substrate.

Such a method advantageously provides, amongst other advantages:

A stable process that is capable of operating continuously, in the case of a substrate being fed continuously;

Increased accuracy and control to reduce the volume of liquid metal, allowing deposition of thin layers, thus increasing productivity and reducing the operational costs;

Suitability for using a wide variety of alloys, including hard-wearing, corrosion-resistant, reactive, ferrous and non-ferrous;

A single molten line that extends the full width of plates or the full perimeter of polygonal or round cross-sections, thus eliminating weak ties between multiple weld beads;

Smooth as-deposited reduced surface roughness in comparison to known methods;

The ability to employ tubular welding wires, which can be produced in smaller quantities than solid wires and can be helpful in improving homogeneity over a wide range of compositions;

Lower capital investment arising from the use of commercially available welding power sources.

Preferably the at least one property includes temperature. Preferably the method further comprising: monitoring the temperature of the process zone, in an area in proximity to the process zone and/or the substrate.

Preferably, the method further comprising: controlling the temperature of the process zone, the area in proximity to the process zone and/or the substrate in response to the monitored temperature.

Preferably, the process zone is provided in a mould.

Preferably, the method comprising: moving the mould relative to the substrate.

Preferably the method comprising: moving the substrate relative to the mould.

Preferably, the method further comprising: generating at least one localised zone of molten material within the process zone, whereby a portion of the molten material within the at least one localised zone is deposited on the substrate.

Preferably, the method comprising: providing the substrate to the input from a roll.

Preferably, the method comprising: providing the substrate to the input discrete planar portions.

Preferably the method comprising: cutting the substrate using a cutting means provided between the process zone and the output or after the output. According to a second aspect, the invention provides an apparatus for cladding a substrate, the apparatus comprising:

a mould comprising a process zone having controllable properties, wherein, in use, the substrate passes in proximity to the process zone and is clad with a material of the process zone.

Such an apparatus advantageously provides, amongst other advantages:

A stable process that is able to operate continuously, in case a substrate is fed continuously;

A single molten line that extends the full width of plates or the full perimeter of polygonal or round cross-sections, thus eliminate weak ties between multiple weld beads;

Smooth as-deposited reduced surface roughness in comparison to known methods;

Preferably a plurality of tubular wires traverse the length and/or width of the mould and/or process zone.

Advantageously this provides the ability to employ tubular welding wires, which can be produced in smaller quantities than solid wires and can be helpful in improving homogeneity over a wide range of compositions.

Preferably the apparatus for cladding a substrate, the apparatus comprising: a substrate input; a substrate output; means configured to direct the substrate from the input to the output; and a process zone located between the input and the output, wherein the process zone is operable to deposit a liquid material therein on the substrate in a substantially uniform manner across a portion of the surface of the substrate moving relative thereto.

Preferably the apparatus further comprising a temperature monitoring means operable to monitor the temperature of the process zone, an area in proximity to the process zone and/or the substrate. Preferably the apparatus further comprising a cooling means operable to control the temperature of the process zone, the area in proximity to the process zone and/or the substrate in response to the monitored temperature.

Preferably, the process zone is moveable relative to the substrate.

Preferably, the substrate is moveable relative to the process zone.

Preferably, the process zone is provided in a mould. Preferably, the process zone comprises at least one heat generation means associated therewith, operable to create a localised zone of molten material within the process zone for deposition of the molten material within the localised zone on the substrate passing in proximity to the process zone. Preferably the apparatus further comprising monitoring means to monitor a position of the substrate, the process zone, a feed rate of the substrate to the input and/or a speed of the substrate passing from the input to the output.

Preferably the apparatus further comprising means for adjusting the position of the substrate, the process zone, the feed rate of the substrate to the input and/or the speed of the substrate passing from the input to the output in response to the monitoring means. In a third aspect there is provided a process mould for continuous cladding of a substrate, comprising: a mould, operable to retain molten material therein; a process zone, operable to transfer the molten material from the process zone onto the substrate moving relative thereto.

Preferably the process mould comprising at least one heat generation means operable to generate a localised area of molten material within a portion of the process zone. Preferably the heat generation means are moveable within the process zone. Preferably the heat generation means comprise welding electrodes. Preferably the process mould comprises means to receive molten material.

Preferably, the process zone is configured to contact the surface of the substrate passing in proximity thereto.

Preferably, the process mould having a process zone having a substantially polygonal cross section.

Preferably, the process mould having a process zone having a substantially planar cross section. Preferably, the process mould having a process zone having a substantially cylindrical cross section.

In a fourth aspect there is provided a hardfaced plate fabricated using the above method.

In a fifth aspect there is provided a hardfaced plate fabricated using the above apparatus. In a sixth aspect there is provided a hardfaced plate fabricated using the above process mould.

Figure 1 shows a schematic diagram of an apparatus for the continuous production of hardfaced plate using a coiled base plate as a substrate, a mould and a process zone;

Figure 2 shows a schematic diagram of an apparatus for the continuous production of hardfaced plate using cut plates as substrate;

Figure 3 shows a top view of the process zone of the apparatus of Figure 1 showing multiple welding oscillating electrodes for the continuous cladding of a plate; Figure 4a shows a side view of an apparatus for the continuous cladding of a polygonal or cylindrical substrate having a moving mould and a fixed process zone;

Figure 4b shows a side view of an apparatus for the continuous cladding of a polygonal or cylindrical substrate having a fixed mould and a moving process zone;

Figure 5a shows a top view of the mould and process zone of Figures 4a or 4b showing multiple welding oscillating welding electrodes for the continuous cladding of a polygonal; and

Figure 5b shows a top view of the mould and process zone of Figures 4a or 4b showing multiple welding oscillating welding electrodes for the continuous cladding of a cylindrical substrate.

In its simplest form, a volume of liquid metal can be generated using one or more suitable heat sources and can be sustained indefinitely as long as the heat source is active. A process zone can be defined as a region that contains liquid metal. Examples of liquid metals include cobalt-based alloys (such as stellite), nickel-based alloys, Manganese Alloys, chromium carbide alloys and NOREM, tungsten-based alloys, titanium-based alloys, or stainless steels. Other corrosion resistant materials, such as gold, platinum, CoCr alloys, glass, paints or polymers or any suitable material may also be used. It will be appreciated that a temperature of a hot process zone is dependent on the specific material used and/or the desired properties of the cladded plate.

Such a process zone may be contained within a mould, i.e. a structure capable of containing liquid metal therewithin, whereby the mould is formed of suitable material for holding molten material, for example ceramic or a metal material having a higher melting point than the liquid metal within the process zone.

Heating is produced locally in the process zone of a mould by using conventional welding-related methods, or can be produced away from the process zone, in case of direct pouring of liquid metal.

Examples of local heat generation are electro-slag welding, electrogas welding, metal-inert gas welding and tungsten inert gas welding, which may use tubular or solid wires and that are not prone to slag entrapment, cold laps and other deleterious problems. Examples of distant heat generation are melting of metals in one or multiple crucibles, with concomitant or periodic pouring into the process zone. In order to remain stable, heat must be removed through adequate cooling systems; this comprises cooling of the mould and of the substrate or component when possible. The condition for stability is the achievement of a quasi- stationary state such that the feed rate of the substrate (or removal rate) is precisely controlled to match the melting rate of filler, that the liquid metal is adequately maintained within the process zone and that there is a precise controlled balance between heat generation and heat removal. When cladding a plate, the process zone takes the shape of a line that extends from edge to edge of an un-clad substrate plate. The cladding process is stable and continuous when the speed of the plate being fed is proportional to, and consistent with the feed rate of molten metal, provided that the molten metal is properly maintained in the mould.

The continuous cladded substrate can be cut to the required dimensions after exiting the process zone to a cutting zone or output zone. Figure 1 shows a schematic diagram of an apparatus 1 for the continuous production of a hardfaced plate using a substrate 2 in a stored form e.g. coiled base plate, whereby the substrate 2 is directed through a mould 4, a cooling system 5, and a process zone 6 to an output zone 8 and/or cutting zone 9 using a plurality of suitable guidance means e.g. rolls. The rolls may comprise any combination of alignment rolls 10, deflector rolls 12 and or straightening rolls 14 as appropriate with regards to consideration as to space, cost and/or specific application, as will be appreciated by the skilled person. The cooling system 5 is used to control the temperature of the area and devices surrounding the cooling system 5, e.g. the substrate 2, the mould 4 and/or the process zone 6. The cooling system 5 comprises a coolant inlet 3a and/or outlet means 3b for circulating coolant around the system using a coolant distributor (not shown) e.g. internal motor/pump as required, thereby cooling the exterior of the cooling system, or whereby a fan can distribute cold air from within the cooling system 5 to outside the cooling system 5 to cool e.g. the substrate 2, mould 4 and/or process zone 6. Alternatively, the cooling system 5 may not use coolant but may in fact use an electrical cooling means e.g. Peltier plate, fan etc.

The substrate in coil format provides for lower production costs. The cooling system 5 may also be communicable and controllable by a system computer (not shown) and may comprise a suitable computer controlled temperature monitoring means (not shown) to ensure that the temperature of the substrate 21 mould 4 and/or process zone 6 are as required to obtain the desired qualities of the deposited material, and controlling the temperature of the elements as necessary.

For example a laser temperature monitoring system in communication with an external computer to monitor the temperature of the substrate 2 as it is fed into and through the mould 4/process zone 6, or to monitor the temperature of the mould 4 and or process zone independently of the substrate, and to subsequently control the cooling system to obtain a desired temperature may be used.

It will also be seen that the mould 4 may also comprise an internal or external cooling system associated therewith, separate from and working independent from or in conjunction with, or formed integral to the cooling system 5 described previously, which can monitor and control the temperature of the mould 4 the process zone 6 and/or the substrate 2 using a suitable cooling method e.g a coolant circulating system/fan/Peltier device. The cooling system of the mould 4 may also be communicable with and controllable by the system computer and/or the cooling system 5. The positioning of the mould 4 and the cooling system 5 are all adjustable both in the horizontal/vertical direction so that the position of each can be adjusted relative to the substrate 2. The position of the mould 4 and the cooling system 5 may also be controlled by the system computer as necessary. The coiled substrate 2 is positioned into an adequate coil holder 16 that also acts as a controlled dispenser. The coil holder 16 may be computer controlled e.g. by a system computer (not shown) to feed the substrate 2 at a rate desired by a user or determined by the apparatus 1 . A monitoring device 18 e.g. laser, camera etc communicable with the system computer (not shown) may monitor the speed, angle and direction of the substrate 2 being fed from the coil holder 16, whereby the feed rate of the substrate 2 can be controlled by the system computer as necessary. The substrate 2 can be mild steel, stainless steel, low-alloy ferrous material, iron or high-alloy ferrous material, cobalt-based alloy, nickel-based alloy or a copper- based alloy or any other suitable material as will be appreciated by a person skilled in the art.

The substrate is aligned, re-directed and straightened with help of adequate means; in the example given this is achieved respectively with alignment rolls 10, deflector rolls 12 and straightening rolls 14.

After a new coil of substrate 2 is positioned in the coil holder 16, the substrate 2 is fed through the alignment rolls 10, deflector rolls 12, (and straightening rolls 14 if required for a particular application) and into the mould 4. Initially, once the leading edge of the substrate 2 enters the mould 4, the cladding process begins whereby one face of the substrate 2 is clad at the process zone 6 to form a plate 13 having a base plate side 15 substantially devoid of any cladding material thereon and a hardfaced side 17 having a substantially continuous cladding layer applied thereon. The plate 13 is then re-directed and straightened and the process runs continuously or as required to produce batches and can be cut to a size desired by a user using a suitable cutting means 19. It will be seen that suitable monitoring means 18 (e.g. camera, laser etc.) can be used to monitor the position, quality, speed, feed rate etc of the substrate 2 at any moment in time, such that cladding of the substrate can begin or be stopped when required by a user or determined by the system computer or otherwise.

Provision is also made for circumstances whereby substrates are not provided in coil format, but are provided instead as cut parts of finite length e.g. substantially planar plates. Such individual planar plates can be loaded into the apparatus 1 1 so that the planar plates form a continuous substrate, such as described in Figure 2. The use of substantially planar plates negates the requirement for the coil holder 16. Figure 2 shows a schematic diagram of an apparatus 1 1 for the continuous production of hardfaced plate using cut plates as the substrate 22. It will be seen that the apparatus 1 1 is configurationally similar to the apparatus 1 described above in Figure 1 and like numbering will be used throughout to describe similar features therein. The functionality of the features described in the apparatus 1 of Figure 1 also applies to the like numbered features of the apparatus 1 1 in Figure 2. However, in contrast to the apparatus 1 described in Figure 1 above, the substrate 22 used in Figure 2 is a substantially planar base plate (as opposed to being fed from a coiled roll), and therefore, the configurational arrangement of the guidance means (e.g. the rolls 10, 12 & 14) in Figure 2 differs from that of Figure 1 .

In the apparatus 1 1 , once the leading edge of a substrate plate 22 enters the mould 4 the cladding process can begin. The clad substrate 22 is re-directed and straightened using a combination of rollers e.g. 10, 12 and/or 14 and the process runs continuously or as required to produce batches. The cladding process within the process zone 6 may join the individual plates together, which can then be cut to the required dimensions in the cutting zone 9 by cutting means 19 after which the cladded plate can proceed to the output zone 8.

Figure 3 shows a top view of the process zone 6 of the apparatus 1 of Figure 1 showing multiple welding oscillating electrodes for the continuous cladding of a plate; Figure 4a shows a side view of an apparatus for the continuous cladding of a polygonal or cylindrical substrate having a moving mould and a fixed process zone; Figure 4b shows a side view of an apparatus for the continuous cladding of a polygonal or cylindrical substrate having a fixed mould and a moving process zone; Figure 5a shows a top view of the mould and process zone of Figures 4a or 4b showing multiple welding oscillating welding electrodes for the continuous cladding of a polygonal; and Figure 5b shows a top view of the mould and process zone of Figures 4a or 4b showing multiple welding oscillating welding electrodes for the continuous cladding of a cylindrical substrate. In order to achieve full width coverage of a planar substrate, a sufficient number of equally spaced solid or tubular welding wires is used, which then oscillate back and forth along the width of the substrate 2 or 22, using electroslag, electrogas or un-shielded open arc. This is the configuration shown below in relation to Figure 3.

The process zone 6 comprises hot and/or liquid material e.g. molten metal which is stably confined between the mould 4 and the moving substrate 2 or 22. The heat is generated by means of electric arc, resistance heating or any other suitable means. In the example shown, six welding wires (not shown) are individually energized such that they each develop an individual electric arc, thereby producing a local molten zone 20a - 20f. Suitable protection against contamination is provided through an inert gas, welding flux or other appropriate means. By oscillating the group of wires along the width of the mould, adequate liquid metal coverage is achieved and the entire sheet width is cladded.

Full width coverage of a substrate can also be achieved by using a sufficient number of melting pots or ladles that continuously dispense molten metal in the process zone using an adequate device such as a tundish, which is continuously filled with ready molten metal. The continuous feeding of the ladles can be achieved in turn via separate welding processes, using electroslag, electrogas or un-shielded open arc, or by ladle filling. Therefore, a sustainable supply of molten cladding metal is obtained to allow continuous running of the operation. As demonstrated in Figures 4a and 4b, when cladding an elongated component 24 with a shaped cross section e.g. a rectangular/polygonal/cylindrical metal block, the mould 4 containing the process zone 6 therewithin extends around the perimeter of the shaped component 24 as the component 24 passes through the mould 4. If the elongated axis of the component is placed vertically, either the component 24 can be fed through a fixed mould 4 (Figure 4b), or a moving mould 4 can be moved up with the component fixed (Figure 4a), or it will be seen that both the mould 4 and component may be moving either in the same direction or in opposite directions relative to each other. The process is stable and continuous when the speed of vertical movement is proportional to, and consistent with the feed rate of molten metal, provided that the molten metal is properly contained within the mould 4. As the component 24 passes through the mould 4, and the process zone 6 therewithin, the surface of the component 24 is clad to form a component with a cladded surface 26. The mould 4 will also comprise a suitable cooling means e.g as described above in Figure 1 e.g. by circulating coolant via the coolant input 3a and coolant output 3b.

The shape of the mould 4 and the process zone 6 can be formed to suit the specific shape of a component to be clad. For example as shown in Figures 5a and 5b, the substrates are polygonal and cylindrical in shape respectively, whilst the mould 4 and the process zone 6 are shaped to accommodate and clad the different shapes of the components of Figures 5a and 5b respectively. In order to accommodate different shaped components, a mould 4 and/or process zone 6 may comprise a plurality of tubular wires evenly distributed within the mould 4/process zone 6, which oscillate along the perimeter width of a required substrate shape as indicated by the local molten zones 28a - 28f and 30a - 30f in Figures 5a and 5b respectively to achieve the required coverage of a specific shaped component using electroslag, electrogas or un-shielded open arc.

Another possible configuration consists of one or more melting pots that continuously dispense molten metal in the process zone, where the pots are continuously filled with ready molten metal, or are fed continuously by one or more tubular wires, using electroslag, electrogas or un-shielded open arc.

In case of a component with a cylindrical cross-section, the component can additionally rotate continuously in order to improve the liquid flow and melting pattern in the process zone.

Claims

A method for cladding a substrate using an apparatus having a substrate input, and substrate output, means for directing the substrate from the input to the output and a process zone located between the input and the output having a liquid material therein, the method comprising:

controlling at least one property of the process zone; moving the substrate in relative to the process zone such that the liquid material within the process zone is deposited on the substrate; directing the substrate having the material deposited thereon to the output.

The method according to claim 1 wherein the at least one property includes temperature.

The method according to claim 2 further comprising:

monitoring the temperature of the process zone, in an area in proximity to the process zone and/or the substrate.

The method according to Claim 3, further comprising :

controlling the temperature of the process zone, the area in proximity to the process zone and/or the substrate in response to the monitored temperature.

The method according to any preceding claim, wherein the process zone is provided in a mould.

The method according to claim 5 comprising:

moving the mould relative to the substrate.

The method according to claim 5 comprising:

moving the substrate relative to the mould. The method according to any preceding claim further comprising:

generating at least one localised zone of molten material within the process zone, whereby a portion of the molten material within the at least one localised zone is deposited on the substrate.

The method according to any preceding claim comprising:

providing the substrate to the input from a roll.

The method according to any of claims 1 to 9 comprising:

providing the substrate to the input as discrete planar portions.

The method according to any preceding claim comprising:

cutting the substrate using a cutting means provided between the process zone and the output or after the output.

An apparatus for cladding a substrate, the apparatus comprising:

a substrate input;

a substrate output;

means configured to direct the substrate from the input to the output; and

a process zone located between the input and the output, wherein the process zone is operable to deposit a liquid material therein on the substrate in a substantially uniform manner across a portion of the surface of the substrate moving relative thereto.

The apparatus as claimed in claim 12, further comprising a temperature monitoring means operable to monitor the temperature of the process zone, an area in proximity to the process zone and/or the substrate.

The apparatus according to Claim 13, further comprising a cooling means operable to control the temperature of the process zone, the area in proximity to the process zone and/or the substrate in response to the monitored temperature. The apparatus according to any of claims 12 to 14, wherein the process zone is moveable relative to the substrate.

The apparatus according to any of claims 12 to 14, wherein the substrate is moveable relative to the process zone.

The apparatus according to any of claims 12 to 16, wherein the process zone is provided in a mould.

The apparatus according to any of claims 12 to 17, wherein the process zone comprises at least one heat generation means associated therewith, operable to create a localised zone of molten material within the process zone for deposition of the molten material within the localised zone on the substrate passing in proximity to the process zone.

The apparatus according to any of claims 12 to 18, further comprising monitoring means to monitor a position of the substrate, the process zone, a feed rate of the substrate to the input and/or a speed of the substrate passing from the input to the output.

The apparatus according to any of claims 12 to 19, further comprising means for adjusting the position of the substrate, the process zone, the feed rate of the substrate to the input and/or the speed of the substrate passing from the input to the output in response to the monitoring means.

A process mould for continuous cladding of a substrate, comprising: a mould, operable to retain molten material therein;

a process zone, operable to transfer the molten material from the process zone onto the substrate moving relative thereto. The process mould of claim 21 , comprising at least one heat generation means operable to generate a localised area of molten material within a portion of the process zone.

The process mould of claim 22, wherein the heat generation means are moveable within the process zone.

The process mould of any of claims 22 or 23, wherein the heat generation means comprise welding electrodes.

The process mould of claim 21 , comprising means to receive molten material.

The process mould of any of claims 21 to 25, wherein the process zone is configured to contact the surface of the substrate passing in proximity thereto.

The process mould of any of claims 21 to 26, having a polygonal process zone.

The process mould of any of claims 21 to 26, having a substantially planar process zone.

The process mould of any of claims 21 to 26, having a substantially cylindrical process zone.

A hardfaced plate fabricated using the method of any of claims 1 to 1 1 .

A hardfaced plate fabricated using the apparatus of any of claims 12 to 20.

A hardfaced plate fabricated using the process mould of any of claims 21 to 29.