WO1992015451A1

WO1992015451A1 - Multibond hardfaced composites

Info

Publication number: WO1992015451A1
Application number: PCT/US1992/001644
Authority: WO
Inventors: Roman F. Arnoldy
Original assignee: Arnoldy Roman F
Priority date: 1991-03-05
Filing date: 1992-02-28
Publication date: 1992-09-17
Also published as: CA2105396A1; ZA921494B; AU1557092A

Abstract

Disclosed are multibond hardfaced composites in which hardfacing particles (12) are welded to steel members (10) in different planes from the surface (16) to be hardfaced. This provides high performance hardfacing to thickness not permitted by prior art hardfacing. A number of embodiments and applications of the invention are disclosed.

Description

Multibond Hardfaced Composites Field of the Invention

The field of the invention is hardfacing and providing wear resistance to industrial equipment. Background of the Invention

A principal cost to the industrial establishment each year is in metal structure and equipment destroyed by abrasion from loose materials such as sand, rock and other silicious compounds.

Various means are employed to combat this abrasion, and nearly all of these means are with metal as other materials do not have the strength to withstand the heavy abuse experienced in these uses. Depending on the nature of the service, the protecting material is usually a compromise between a metal or metal composite of high hardness with accompanying brittleness and lower hardness with accompanying toughness, the highest abrasion resistance being obtained from a composite of very high hardness carbides in a se ihard metal matrix. This material can only be used on a large area basis as a welded-on layer no greater than about 3/8" thick and only for pure scratch abrasion such as sand flowing by gravity down a chute.

When the service involves absorption of higher energies such as high velocity particle impingement or from impacts such as from falling rocks, the carbide-matrix combination must be of a softer and hence tougher type to avoid spalling and breakout of the facing. Use of these softer material results in greater erosion of the component and hence shorter life. The usual types of metal protection are heat treated steel, case hardened steel and hardfaced steel bar or plates, with a unit of thickness of high performance hardfacing being equivalent to 5 to 20 units of thickness of hardened steel in equivalent wear life in pure scratch abrasion. As the need for energy absorption increases, the hardfacing must be dropped back to lower hardness carbides in a softer and tougher matrix to avoid spalling and breakage; so the advantage over steel becomes less.

As the need for energy absorption continues to rise, it reaches an area where the entire part can be made from a lower hardness carbide containing alloy that is produced as a "hard metal casting" of which thousands of tons are produced and used yearly. For still higher energy absorption needs, the hard metal casting will not resist breakage, and a heat treated steel must be used. Here we are at a level where there is extreme toughness but such low hardness that very thick and heavy sections are required to give anything acceptable in wear life. So hard metals used in current forms have reciprocal limitations.

Beside the employment of hard metals by weld applied coatings, hard metals are used in one other form, that of hard metal castings. Both of these modes have their limitations. The weld applied coating is limited in depth to about 3/8" of high performance hard metal. The hard metal casting must be lowered in hardness and type of carbide contained to avoid brittleness and breakage.

The most cost effective hardfacing used in industry is called a high chrome iron. It consists of a main body of iron with up to about 30 percent chromium and up to about 4 1/2 percent carbon and is low in cost because it is made directly from ferrochromium and plain low carbon steel. This general class of material can have varied properties, depending upon its analysis. One version of it is as a cast alloy used for a variety of different types of industrial equipment subject to abrasion. One name for this alloy is HC-250, originally developed by American Brake Shoe Company. It has about 27 percent chromium and about 2 1/2 percent carbon and the balance iron. This alloy has a content of about 20 percent chromium carbides of a type which have about 1,000 Bhn and would be of one or more of the analyses

or Cr₃C. In the annealed state it can be machined and has good toughness. However, its composite hardness is such that it is below the level of silica (Si0₂) , which is the component that gives hardness to most loose materials found on the earth. It therefore tends to have limited life when subject to the abrasion of silicious materials. On the other hand, another form of this class of alloy has up to 30 percent chromium and 4 to 4 1/2 percent carbon. This alloy forms carbides of the analysis of Cr₇C₃ in combination with iron, generally termed M₇C₃, which have a hardness of about 1700 Bhn, which is well above the hardness of the silicious materials usually handled. Its performance in abrasion with such materials is outstanding and its cost is still low since it is also made directly from ferrochromium and iron. This alloy is used as a hardfacing applied by welding up to the depths of about 3/8". It cannot be made other than as a very small casting because of its brittleness characteristic. This alloy was used first on a large area basis in facing large diameter pipe for use in handling

S catalysts in the refining industry. It was early recognized that the Cr₇ or M₇C₃ carbide was necessary to give it good performance and long life and this was specified as early as 1954 for the production of lift pipe for use in TCC cracking units in the refining industry.

Fully faced plates, for example 4• by 9' dimensions, were developed and introduced in 1965. Here again the need for the M₇C₃ carbide was evident in the variety of services to which these plates were put. To obtain that carbide, of course, required an analysis containing in excess of 4 percent carbon.

Examples of such hardfacing plates are illustrated in U.S. Patent Nos. 3,402,459; 3,407,478 and 3,494,749, but the thickness of their hardfacing cannot exceed about 3/8".

Other facings containing carbides such as of columbium, vanadium, molybdenum, and titanium would provide such performance, but their cost is so much greater that they are not cost effective for large area coverage.

Considering the hard metal facing, each bit of hard metal has less support as distance between it and the point where it is welded to its steel backing increases. Hence the limitations on the depth of high performance facing which can be used.

Since the hard metal is welded to steel at only one of its dimensions, its usual effective depth is limited to about 3/8". Hard metal castings can be produced in heavy thickness, but their matrix hardness and their type of carbides must be of low enough hardness that they will not break in service. The result is more rapid wear. Resistance to abrasion in the metals field has been accomplished historically by the use of hardened plate and bar, by case hardening of the same or by hardfacing these forms. Through hardened forms are of lowest cost but also of lowest hardness and length of life, experiencing the greatest unit metal loss in a given abrasions situations. Through hardening must be kept to a relatively low value as higher hardness in a through hardened piece will cause brittleness and breakage.

Case hardened forms present a harder surface and will outwear the through hardened forms per unit of weight loss, but the cases are so thin that the total life will still be relatively short as compared to through hardened material where a few times the total thickness of piece is allowable.

Hardfaced forms will give the greatest life and least loss of material in a given abrasion situation, but a really effective facing of hardfaced forms cannot be applied at a depth great enough to give long life in heavy abrasion situations. Also in such situations the facing will chip and be prematurely lost by flexing of the base and/or impact by high energy particles.

Summary of the Invention

In the present invention instead of being welded only in a plane parallel to the surface of the base plate, the hardfacing is also welded to steel members in different planes, such as planes transverse to the plane of the base and can be welded, mechanically secured or not to the base plate. The base plate may be formed of any mild steels and the like which are relatively ductile, malleable and weldable and which may be cut, bent, shaped, welded or bolted to a surface to be made abrasion resistant. The base plate can also be the surface to be hardfaced. The hardfacing or abrasion resistant material comprises particles of carbide containing alloy materials. The transverse steel elements have a thickness and are spaced apart a distance which reduces fracturing of the hardfacing or abrasion resistant particles or materials. It is an object of the present invention to provide a multibond hardfaced composite which provides high performance hardfacing to any practical thickness desired.

A further object of the present invention is the provision of a multibond hardfaced composite having a mild steel base plate and steel members in planes different from that of the base plate and hardfacing particles welded to one or both of the base plate and the steel members, the steel members being spaced apart a distance which reduces fracturing of the hardfacing particles.

A further object of the present invention is the provision of multibond hardfaced composites of any desired practical thickness having the strength required for heavy abusive services.

Other and further objects and features appear throughout the specification and claims. Brief Description of the Drawings

Figure 1 is a vertical sectional view of a multibond hardfaced composite in the form of a hardfaced bar according to the invention.

Figure 2 is a vertical section of multibond hardfaced composites in the form of a hardfaced slab according to the invention.

SUBSTITUTE SHEET Figure 3 illustrates the hardfaced slab of Figure 2 tacked or fillet welded to a substrate. Figure 4 is a vertical section of the multibond hardfaced composites in the form of a grate. Figures 5 and 6a illustrate the multibond hardfaced composites in the form of tiles secured together and to a surface.

Figure 6B is a side view of the multibond hardfaced composites in the form of tiles mechanically interlocked.

Figure 7 illustrates a plurality of the multibond hardfaced composites secured to a roll.

Figures 8-13 illustrate various forms, uses and applications of the multibond hardfaced composites according to the invention.

Figure 14 is a graph showing the relative distance between supports satisfactory for low and high hardness metals for parallel supports and tube filled supports. Figure 15 is a perspective view of a lamina bar or sandwich of hardfaced composites according to the invention.

Presently Preferred Embodiments of the Invention As previously mentioned, the multibond hardfaced composite of the present invention comprises hardfacing particles welded to steel members in different planes, such as transverse to the plane of the surface to which they are to be secured by welding or mechanical means. This provides heavy support to each elemental mass of facing on two sides, as well as on the bottom, which allows the facing to absorb high energy inputs as impact or shock in compression in which the material is strong without being subjected to tension or shear in

SUBSTI which it is weak. This allows the use of much harder facing materials (massed primary carbides) in a given service. It also allows employment of hardfaced plate metal to almost any depth to greatly extend service life.

The distance needed between the transverse supports will depend on the brittleness (composite hardness) of the hard metal. The higher the composite hardness, the closer together must be the transverse steel supports to which it is welded. The actual dimensions are determined by trials in service in a given application.

Hardfacing metal will vary from low hardness such as 800 Bhn carbide in a 200 Bhn matrix all the way to 1700 Bhn carbides in a 450-500 Bhn matrix. The preferred facing to be used in this invention because of most abrasion resistance for the cost is the AWS classification Fe Cr A-l high carbon. This is principally an alloy of 15 to 30 percent Cr with 2-5 percent carbon. The bonding of the high hardness carbide facing in different planes gives it the strength required for use in heavy abuse services and provides longer life in all services. It allows the use of high performance hardfacing to any practical thickness desired.

The amount of distance required between an elemental mass of high carbide metal and the point where it is welded to a steel transverse member will also vary with the form of the structure. The enveloping forms such as pipe tube or hex and square structures will allow the largest unsupported distance to a transverse steel element, for example up to about 3 1/2". In the case of nonenveloping forms, the transverse or cross members can be spaced up to about 3" apart.

Referring to Figure 14, the graph illustrates satisfactory spacing between parallel supports and tube-shaped supports for AWS Fe Cr A-l type facings. For example, in the case of transverse numbers, the thickness is up to 1/2" and is spaced apart a maximum of about 3.0". In the case of tubes of any geometric cross-sectional shape, the tubes have a thickness up to 1/2" and a maximum internal diameter of about 3.5".

The spacing of the steel support elements required to accomplish the purposes of the composite varies according to the brittleness and hence lack of ductility of the facing. For abrasion purposes the most brittle facings have the highest hardness and abrasion resistance as explained previously, and will require weld bonding at the shortest distance from a steel support.

Compression tests were run on samples comparing a faced piece of 1.76" diameter with 3/8" thick hardfacing on 1" plate with a 3/16" tube of mild steel the same diameter filled with the same material 4.5 C. Fe Cr A-l (nugget) . The faced piece failed at 83,000 lbs./sq. in. when a piece broke out. The nugget cracked internally at 129,000 lbs./sq. in. but was left intact (and hence usable for abrasion protection) . So even after it had withstood 55 percent more load, it was still available for abrasion service as before. The first field test on the all-face slab installed in a 3 ft. by 10 ft. long area of a bucket in a copper mine showed the slab standing up 1/8" higher than the competing protection next to it, which was a section of bar with hardfacing applied in the conventional manner. In the present invention, the mass of hard metal to be used is bonded in different planes so that no particle of hard metal is an extended distance from its bonding point. The actual longest distance to be allowed depends on the construction and the service. A filled and bonded tube can use a longer distance because the mass at center is surrounded by bonded metal. Lighter impact protection requirement will allow a longer distance of a mass to its point of welded support.

It its preferred form the multibond composite comprises a mass of hard metal bonded on three sides to a steel support which is in close proximity as described above. The base plate may be the surface to be hardfaced or formed of any mild steel which is relatively ductile, malleable and weldable, and which may be cut, bent, shaped and welded or bolted to a surface. Similarly, the cross or transverse members can be of a mild steel.

The following are examples of carbide containing alloy materials or weldable brittle materials which form the hardfacing surface of the multibond hardfaced compositions. Example 1.

Percent

Chromium 27

Carbon 3.5

Balance Iron Example 2.

Percent

Chromium 33

Carbon 3.5-4.5

Balance Iron

SUBSTITUTE SHEET Example 3.

Percent

Chromium 25-33

Manganese 0-8 Carbon 2.5-5

Molybdenum 0-2

Boron *0-5

Iron Balance

Example 4. Percent

Carbon 4

Silicon 0.8

Iron *Balance

Example 5. Percent

Chromium 5

Carbon 2

Boron 5

Iron Balance Example 6.

Percent '

Carbon 3.5

Chromium 18

Boron 4 Nickel Balance

Example 7.

Percent

Chromium 20

Carbon 2 Iron Balance

The following are examples of various uses of the multibond hardfaced composites.

TE SHEET Example 8. Referring to Figure l, a channel form 10 of mild steel is filled with high performance alloy particles 12. The alloy particles 12 are welded and supported on three sides against energy inputs of the service which would otherwise shatter unprotected facing of this width and depth. The channel form 10 can be made of any length to form a bar or can be made in short lengths for convenience in shipping and secured together without decreasing its usefulness. It is attached by fillet welding 14 to a surface 16 to be protected, although it can be attached by bolting or steel welding.

Example 9. Referring to Figure 2 in which the reference letter "a" has been added to like numerals of Figure 1, illustrated is an all-face slab made by filling floor grating with high performance metal 121 against a bottom plate or assembled side by side. The slab is made in various sizes, for example, up to about 1 foot square. These are attached by fillet welding (not shown) to produce large area assemblies as required. This configuration allows flexing of a large area of substrate without causing breakout of the facing. Each slab functions as a small unit of a large area. Example 10.

Referring to Figure 10 which illustrates assembly of the all-face slab of Figure 2, slab 1 is tacked or fillet welded to substrate all around, slabs 2- 3-4 are tacked or fillet welded on right, top and bottom, slab 5 is tacked or fillet welded left, right and bottom, slab 6 is tacked or fillet welded right and bottom, and so on. Example 11.

Referring to Figure 4, a floor grating of multibond hardfaced composites 10b, 12b is illustrated with the reference numeral "b" applied to reference like numerals of the preceding figure, shown secured to the plate.

Example 12.

Referring to Figures 5 and 6, multibond hardfaced components are illustrated in the form of tiles 1, 2, 3, also called nuggets, which may be provided in various geometric shapes, for example, hex, square and round. Individual tiles consist of a tube of the chosen geometric shape of a length equal to the depth of face desired filled with high carbide metal particles which is welded to the sides of the tubes.

Example 13.

The methods of attachment will depend on the service requirement and the skills available to the end user for installation. For example in Figure 5 the tiles 1_/ 2, and 3 are welded as installed. A row of tiles is set out against a side plate which is tacked or fillet welded in place against a base plate. A second row of tiles, not shown, is lined up against the first row and tacked or welded in place until the desired area is covered. This area will have whatever thickness is desired but will be able to flex with the base plate and absorb high energy inputs without damage.

Example 14

Referring to Figure 6, round tiles la, 2a and 3a are assembled by placing two tiles together (as la and

2a) and welding them together and to the base as at "A."

Tile 3a is positioned contacting both tiles la and 2a and similarly welded as at B and C. Other forms of filled tubing can be used and attached to a base plate by tack or fillet welding or mechanical means.

An example of a mechanical interlock method of attachment which does not require welding is illustrated in Figure 6b.

The above are some examples of the use of high performance (and brittleness) hard metal in deep deposits with proximity bonding to give 3-way support. The bottom need not be welded to the surface to be hard surfaced, but can be secured thereto by mechanical means.

Various further applications and uses of the multibonded hardfacing composites are illustrated in Figures 7-13. Figure 7 illustrates a wear bar having multibond hardfaced composites according to the invention attached to a mill roll.

Figure 8 illustrates intermeshing crossbars having multibond hardfaced composites applied according to the invention.

Figure 9a illustrates multibond hardfaced composites applied to bucket teeth according to the invention.

Figure 9b is a cross-sectional view taken along the line A-A of Figure 9b. Grooves are provided in the tooth to form the transverse supports 10, and the hardfacing particles 12 are cast into the grooves in the tooth and are supported by the supports 10.

Figures 10a, b illustrate a hammer mill hammer having multibond hardfaced composites applied to it according to the invention.

Figures 11a, b illustrate a faced bar of multibond hardfaced composites applied to a grader blade according to the invention. Figures 12a, b, c, and d illustrate multibond hardfaced composites as removable shoes according to the invention applied to coal pulverizing rolls.

Figure 13 illustrates flexible hardfacing of multibond hardfaced composites which flex independently of each other for securing to a surface to be hardfaced.

Figure 14 is a graph illustrating satisfactory spacing between supports of parallel bars and filled tubes. Figure 15 illustrates a lamibar in which the mild steel plates 10 serve as the transverse support members for the hardfacing particles 12 welded to the sides of the support members 10. This "sandwich" or composite bar can be as wide as desired and the hardfacing particles 12 as deep as desired, and it can be welded or bolted to a surface to be hardfaced.

Other types of uses, not shown, are hardfacing of blades for graders, dozers, snow plows, grizzly bars, chutes, linings such as for buckets, target plates, and other applications.

The hardest and most brittle facings can be used as they are protected by the steel plates by which they form a sandwich. A heat resisting or abrasion resisting plate may also be used so that the composite presents the maximum form of abrasion resistance available in the metals field for heavy abrasion.

The present invention has the following advantages over conventional hardfacing and hard metal castings of the prior art: 1. It allows the use of high performance facing in energy absorbing uses where softer materials were formerly needed. 2. It allows the use of effective thicknesses many times that possible for

SUBSTITUTE SHEET the same type of hardfacing used in the usual mode.

3. It permits a very thick deposit of hardfacing material to a surface to be hardfaced, such as by bolting or plug welding. As to effective depth, almost any depth may be employed by bonding the facing to suitably placed transverse steel elements. 4. The depth can be any producible by the arc weld casting process, preferably bulkwelding. 5. Because of the greatly enhanced support, harder, higher performance but more brittle metal can be used which outperforms hard metal castings. The uses of the multibond hardfaced composite include the areas now served by hardfacing or hard metal castings plus areas which they are not able to serve. Whilepresentlypreferred embodiments have been given for purposes of disclosure, various changes in and applications and uses may be made which are within the spirit of the invention as defined by the appended claims. What is claimed is:

Claims

Clai s

1. A multibond hardfaced composite comprising, a steel structure having spaced apart steel supports positioned transversely to a surface to be protected, hardface metal deposited between and bonded to both of the transverse supports, the transverse steel supports having a thickness and spaced apart a distance effective to reduce fracturing of the multibond hardfacing composite in use.

2. A multibond hardfaced composite comprising, a steel structure having a plurality of spaced apart steel supports positioned transversely to a surface to be protected, hardface metal deposited between and bonded to the transverse steel supports, the transverse steel supports having a thickness and spaced apart a distance effective to reduce fracturing of the multibond hardfaced composite in use.

3. The multibond hardfaced composite of claims or 2 where, the steel elements have a thickness up to about 1/2" and are spaced apart a maximum of about 3", and the hard faced metal deposited has a thickness greater than 3/8".

4. A multibond hardfaced composite comprising, a steel tube of a geometric cross- sectional shape.

iUBSTITUTE SHEET hardface metal cast or welded inside the steel tube to its inner wall, the tube having a thickness and an internal diameter effective to prevent fracturing of the multibond hardfacing composite in use.

5. The multibond hardfaced composite of claim

4 where. the tube has a thickness of up to about 1/2" and a maximum internal diameter of about

3 1/2".

6. The hardfaced surface of Claim 5 comprising, a plurality of the multibond hardface components disposed side by side on a surface to be hardfaced and secured to one or both of the surface and their contiguous sides.

7. A method of hardfacing a surface comprising, securing one or more of the multibond hardfaced composites of claim 1 to the surface.

8. A method of hardfacing a surface comprising, securing one or more of the multibond hardfaced composites of claim 2 to the sur ace.

9. A method of hardfacing a surface comprising. securing one or more of the multibond hardfaced composites of claim 4 to the surface.

10. A method of hardfacing a surface comprising, securing one or more of the multibond hardfaced composites of claim 5 to the surface.

11. A method of hardfacing a surface comprising, individually securing a plurality of the multibond hardfaced composite of claim 1 in side by side relation to the surface effective to permit flexing of the hardfacing.

12. A method of hardfacing a surface comprising, individually securing a plurality of the multibond hardfaced composite of claim 4 in side by side relation to the surface effective to permit flexing of the hardfacing.

13. A method of hardfacing a surface of a steel structure comprising, welding hardfacing metal into transverse grooves in the structure extending from the surface thereby forming transverse supports, the grooves being spaced apart a maximum of 3", the thickness of the supports being up to 1/2".

SUBSTITUTE SHEET AMENDED CLAIMS [received by the International Bureau on 22 July 1992 (22.07-92); original claims 1-4 and 6-13 amended; other claims unchanged (5 pages)]

1. A multibond hardfaced composite comprising, a steel structure having spaced apart steel supports positioned transversely to a surface to be protected, a brittle weldable alloy containing carbide of a hardness above that of silica deposited between and bonded to the transverse supports, the transverse steel supports having a thickness and spaced apart a distance effective to reduce fracturing of the alloy in use.

2. A multibond hardfaced composite comprising, a steel structure having a plurality of spaced apart steel supports positioned transversely to a surface to be protected, a brittle carbide containing weldable alloy having a hardness above that of silica deposited between and bonded to the transverse steel supports, the transverse steel supports having a thickness and spaced apart a distance effective to reduce fracturing of the alloy in use.

3. The multibond hardfaced composite of claims or 2 where, the steel supports have a thickness up to about 1/2" and are spaced apart a maximum of about 3", and the alloy deposited has a thickness greater than 3/8". 4. A multibond hardfaced composite comprising, a steel tube of a geometric cross- sectional shape, a brittle weldable alloy containing carbide of a hardness above that of silica cast or welded inside the steel tube to its inner wall, the tube having a thickness and an internal diameter effective to reduce fracturing of the alloy in use.

5. The multibond hardfaced composite of claim

4 where, the tube has a thickness of up to about 1/2" and a maximum internal diameter of about 3 1/2".

6. A hardfaced surface comprising, a plurality of the multibond hardface composites of Claim 5 disposed side by side on a surface to be hardfaced and secured to one or both of the surface and their contiguous sides.

7. A method of hardfacing a surface comprising, securing to the surface one or more of multibond hardfaced composites comprising spaced apart transverse supports having a brittle weldable alloy containing carbide of a hardness above that of silica deposited between and bonded to the transverse supports, the transverse supports having a thickness and spaced apart a distance effective to reduce fracturing of the alloy.

8. A method of hardfacing a surface comprising, securing to the surface one or more of the multibond hardfaced composites comprising a plurality of spaced apart transverse supports having a brittle weldable alloy containing carbide of a hardness above that of silica deposited between and bonded to the transverse supports, the transverse supports having a thickness and spaced apart a distance effective to reduce fracturing of the alloy.

9. A method of hardfacing a surface comprising, securing to the surface one or more multibond hardfaced composites of a brittle weldable alloy containing carbide of a hardness above that of silica welded or cast to an inner wall of a steel tube of geometric cross-section having a thickness and an internal diameter effective to reduce fracturing of the alloy.

10. A method of hardfacing a surface comprising, securing to the surface one or more of the multibond hardfaced composites of a brittle weldable alloy containing carbide of a hardness above that of silica welded or cast to an inner wall of a steel tube of geometric cross-section having a thickness and an internal diameter effective to prevent fracturing of the alloy, the tube having a thickness of up to about 1/2" and a maximum internal diameter of about 3 1/2".

11. A method of hardfacing a surface comprising, individually securing in side by side relation to the surface a plurality of multibond hardfaced composites of spaced apart steel supports transversely to the surface having a brittle weldable alloy containing carbide of a hardness above that of silica between and bonded to the supports effective to reduce fracturing of the alloy, and effective to permit flexing of the multibond hardfaced composites.

12. A method of hardfacing a surface comprising, individually securing in side by side relation to the surface a plurality of multibond hardfaced composites of a brittle weldable alloy containing carbide of a hardness above that of silica cast or welded inside a steel tube having a thickness and an internal diameter effective to reduce fracturing of the alloy, and effective to permit flexing of the multibond hardfaced composites.

13. A method of hardfacing a surface of a steel structure comprising, welding a brittle alloy containing carbide of a hardness above that of silica cast or welded in one or more grooves in the surface, sides of the groves forming supports for the alloy, the grooves being spaced apart a maximum of 3", and the thickness of the supports being sufficient to support the alloy thereby reducing fracturing of the alloy.