CA1254063A

CA1254063A - Consolidation of a part from separate metallic components

Info

Publication number: CA1254063A
Application number: CA000491861A
Authority: CA
Inventors: Gunes M. Ecer
Original assignee: CDP Ltd
Current assignee: CDP Ltd
Priority date: 1984-10-01
Filing date: 1985-09-30
Publication date: 1989-05-16
Also published as: JPH0149766B2; US4554130A; EP0177209A2; JPS61179805A; MX173087B; EP0177209A3

Abstract

CONSOLIDATION OF A PART
FROM SEPARATE METALLIC COMPONENTS

ABSTRACT OF THE DISCLOSURE

A method of consolidating metallic body means comprises a) applying to the body means a mixture of:
i) metallic powder ii) fugitive organic binder iii) volatile solvent b) drying the mixture , and c) burning out the binder and solvent at elevated temperature, d) and applying pressure to the powdered metal to consolidate same on said body means.

Description

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BACKGROUND OF THE INVENTION

This application is related to U.S. Patent No. 4/562,892.

This invention relates generally 1o metal powder consolidation as applied to one or more metallic bodies, and more particularly to joining or cladding of such bodies employlng powdered metal consolidation techniques.
As describe'd in U.S. patents 3,356,496 and 3,689,259, it is known to utilize a pressurizing medium consisting of refractory particulate matter and high temperatures to consolidate (or densify) a metallic object. In this approach, the pressure applied by a press is transmitted through a hot ceramic particle bed to the hot preformed part having a density less than that of its theoretical density. The pressurization of the part occurring ln all directions causes voids, gaps or cavities within the part to collapse and heal, the part being densified to a higher density which may be equal to its theoretical densityO
Conventional powder metallurgy techniques are limi-ted to the production of parts having shapes that can be produced by closed die pressing in forming of the powder preform.
~ttempts to produce more complex shapes ,having 100~ dersity have required the use of lengthy canniny procedures tl) to protect the part from the pressurizing gas. ~nother approach (2) to po~dered metal consolldation utilizes prefor~s requiring no canning in HIP(i.e. hot isostatic pressing) yet it is limited to the shapes that can be produced by powder pressiny in a die. In all cases, the preform consolidation takes place in a gas pressurized autocl~ve (HIP) which, as mentioned earlier, is suitable for consolidation o~ products whose ~ 6~

properties are not sensi-tive -to long time exposures to high temperatures. HIP is described fully in Reference No. 3.
It is seen, therefore, that developmen-t of a practical powdered metal process able to consolidate lOO~ dense shapes, too complex to produce by die pressing, utilizing short time high temperature exposure and without the need for canning would satisfy a need existent in the metal forming industry.
Such a process would also meet the need for substantially lower parts costs. Prior patents (4 7) relating to the subject oE
isostatic pressing of metal workpieces teach that if the parts being consolidated, or to be joined, have cavities or cracks or clearances between the pieces accessed by the pressurizing gas, complete densifica-tion can not take place. Parts to be consolidated or joined must, therefore, be isolated from the pressurlzing gas by an impermeable casing (8).

SUMMARY OF THE INVENTION

It is a major object of the invention to provide a process or processes meeting the above needs, and otherwise providing unusual advantages as will appear. Joining and cladding processes to be described do not require canning or casings which can be extremely expensive. Further novelty exists in the use of fugitive organic binders and volatile solvents to apply a layer of metallic powders over the surface openings of the voids or clearances between the pieces to be -joined or to be clad. Major objectives include the provision oE:

1. Me-thods of joining two or more metallic objects with the object oE making a ~igger and more comple.Yly shaped shaped object,

2. methods of cladding a metallic object with a layer of another metallic material with or without a layer of third material between the two,

3. a method of combinining two or more metallic and ceramic objects as in l and 2 above and afterward chemically removing the ceramic to provide a predesigned cavity.
The basic method of consolidating metallic body means in accordance with the invention includes the steps:
- a) applying to the body means a mixture of i) metallic powder ii) fugitive organic binder iii) volatile solvent b) drying the mixtures, and c) burning out the binder and solvent at elevated temperature, d) and applying pressure to the powdered metal to o ~olidate same on the bo~y mea~s.

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~, ~ 3 The third mixture may be applied to the body means by dipping, painting or sprayi~g; the body means may have cladd.ing consolidated thereon by the above r.ethod; body means may comprise multiple bodies joined together by the consolidated powder metal in the mlxture; one or more of the bodies to be joined may itself be consolidated at the same time as the applied powder metal in the mixture is consolidated; and the consolidation may take place in a bed of grain (as for example ceramic par-ticulate~ adjacent the mix-ture.

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Further, one of the bodies may comprise a drilling bit core on which cladding is consolidated; and/or to which another body (such as a nozzle or cutter) is joined by the consolidation technique; and one of the bodies may comprise a stabilizer sleeve useful in a well bore, and to the exterior of which wear resistant cladding is consolidated, or to which a wear resistant pad or pads are joined by the method of the invention.

_. -6 The invention is also concerned with provision o~
cu-tting elements which are made integral with roller bit cone structure, as by consolidation techniques. As the bi-t is rotated, -the cones roll around the bottom of the hole, each tooth intermittently pene-trating in-to the rock, crushing, chipping and gouging it. The cones are designed so tha-t the teeth intermesh, to facilitate cleaning. In so~t rock formations, long, widely-spaced steel teeth are used which easily penetrate the formation.
These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following specification and drawings, in which~

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DRAWING DESCRIPTION

Fig. 1 is an elevation, in section, showing a two-cone rotary drill bit, with in-termeshing -teeth to facilitate cleaning;
Fig. 2 is an elevation, in section, showing a milled tooth conical cutter;
Fig. 2a is a cross section taken through a tooth insert;
Fig. 3 is a flow diagram showing steps of a manufacturing process for the composite conical drill ~it cutter;
Figs 4(a) and 4(c) are perspective views of a conical cutter tooth according to the invention, respec-tively before and after downhole service use; and Figs. 4(b) and 4(d) are perspective views of a prior design hardfaced tooth, respectively before and after downhole service;
Figs. 5(a)--5~d3 are elevations, in section, showing various bearing inserts employed to form in-terior surfaces of proposal concial cutters; and Fig. 6 is an elevation, in section, showing use of powdered metal bonding layer between a bearing insert and the core piece;
Figs. 7 and 8 show process steps;
Fig. 9 is a side elevation showing a drill bi-t to which wear resistant cladding has been applied and to which nozzle and cutter elements have been bonded;
Fig. 10 is a side elevation of a stabilizer sleeve processed in accordance wi-th the invention;
Fiy. 11 is a horizontal section through the Fig. 10 sleeve;

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Fig. 12 is an enlarged view showing a part of the Fig.
10 and 11 sleeve;
Fig. 12a is a fragmentary view;
Fig. 13 is a section showing joininy of two bodies.

DETAILED DESCRIPTION

In Fig. 1, the illustrated improved roller bit cutter 10 processed in accordance with the invention lneludes a tough, metallic, generally conical and fracture resistant eore 11. The core has a hollow interior 12 and defines a central axis 13 of ro-tation. The bottom of the core is tapered at 14, and the interior ineludes multiple sueeessive zones 12a, 12b,12c and 12e eoneentrie .

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-to axis 13, as shown. An annular metallic radial ~sleeve type3 bearing layer 15 is carried by the core a-t interior zone 12a -to support -the core for rota-tion. Layer 15 is a-ttached to anrLular surface 11_ of the core, and ex-tends about a~is 13. It consists of a bearing alloy, as will appear.
~ n impact and wear resistan-t metallic inner layer 1 is attached ~o the core at its interior ~ones 12b-12e, to prov~de an axial thxust bearing; as at end surface 16a A
plurali~y of hard metallic ~eeth 17 are carried by the core, as for example integral therewith at ~he root ends 17a of the teeth. The teeth also have portions 17b that protrude outwardly, as shown, with one side of each'tooth carrying an impact and wear resistant layer 17c to provide a hard cutting edge 17d . .:
as the ~-t cutter ro-tates about axis 13. At least some of the 15 teeth ëxtend about axis 13, and layers 17c face in the sa~e rotary direction. One tooth 17' may be loca-ted at the extreme - outer end o~ the core, at axis 13. The teeth are spaced apart .~ ~ Finally, a wear resistant outer metallic skin or layer 19 is o~ and attached to the core exteriox surface, -to exten~ -completely over ~hat surface and be-tween the teeth .17.
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In accordance with an important aspect o~ ~he invention, at least one or -two layers 15, 16 and 1~ consists essentiall~
o~ consoliaated pow~er metal, and pre-~erably all three layers - consis-t or such consolidated powder metal~ A variety o~
manufacturing schemes are possible using the herein ~isclosed .
ho-t pressing technique and the alternative means o~ applying the surEace layers indicated in Fig. 2. It is seen from the previous discussion that surEace layers 15, 16 and lg are to have quite different engineering properties than the inter.ior core section 11. Similarly, lcLyers 16 ~nd 19 shou'ld be di~ferent than 15, and even 16 should differ from 19 Each o~ these layers ancl the core piece 11 may, -therefore, be manuEac~ured separa-tely or applied in place as powder mi~tures prior to cold pressing:
Thus, there may be a number of possible processing schemes as S indicated by arrows in Fig. 3. The enci.rcled nu~bers in this figures reEer to the possible processing steps (or operations) listed in below Table 1. Each continuous path in the figure~
starting from Step No. 1 and ending at Step No. 15, defines separate processing schemes which, when followed,- are capable ~ 10 of producing integrally consolidated composite conîcal cu~ters.

- A list of major processing steps which may be included in the processing:
1. Blend powders.
~5 .. 2~ Cold press powder to pre-form green interior core .
. .: . piece 11 (see Figure 2 for location), which : ... . . .
~ --.- includes teeth 17.
- ,. .: , :
3. Cold press and sinter or hot press po-~der to ~. pre-form~ less than fully dense, core piece 11.

. Sintering or hot pressing can usually be. aone at .... a pre~erred temperature range l80~F to 1250F~

I~ sintered, typical sin~er.ing times may be - . 0.5 to 4 hours depending on -temperature.

4. Forge or cast fully dense core piece 11 2~ 5. Apply powdered hard mekal compound sXin 19;

i.e., by painting, slurry dipping or cold spra~ing a hard metal powder mixed with a fugitive organic binder and a volatile solvent.

6. Place tungsten carbide inserts 17c on -teeth faces 7. Apply -thrust-bearing-alloy powder layer 16; i e , by painting, slurry dipping or cold spraying an alloy binder mixture as in Step 5 above.
8~ Apply powdered radial bearing alloy 15 in the S core piece; i.e., by painting, slurry dippin~ or cold spraying an alloy-binder mixture as in Step 5 aDove.
9. Apply p~redradial blaring alloy 15 in the cold piece; i.e., by painting, slurry dipping or cold } spraying an alloy-binder mixture as in Step 5 above.
10. Place wrought, cast or sintered powder metal radial bearing alloy 15 in the core piece 11 11~ Bake or dry ~o remove binder from powder layers 15, 16 and/or 19. Drying may be accomplished at room temperature overnight. If slurry applied layers a~e thicX the preform may be baked in non ~, - oxidizing atmosphere at 70-300F for several hours to assure comple-te volatilization o~ the vola-tile portion of the binder~
:- : . -12. Hot press to consolidate the composi~e into a full~ dense (g~ of theore~ical density~ conical ., ... , , -, ~ . , . - - ::., cutter. Typically, ho~ pressing temperature range of 1900-2300F and pressures OL 20 to 50 tons per - .
square inch may be required.
Z5 13 Weld deposit radial-bearing alloy 15 in th2 densified ~one.
14. Final finish; i.e., grind or machine ID profile, ~inish grind hearings, finish machine seal sea-t, inspect, etc.

-12_ The processing outlined include only the ma~or s-teps involved in the flow of processi~g operationS. O.her secondary operations that are rou:tinely used in most processing schemes for similarly manufactured products, are not included for sake o~ simplicity. These ma~ be cleaning, manual patchwork to repair small deEects, grit blas-tin~ to remove loose particles or oxide scale, dimensional or structural inspections, etc All of the processing steps are unique, as may easily be recogniæed by those who are familiar with the metallurgical arts in the powder metals processing filed.. Each scheme provides a number of benefits from the processing point of view, and some o~ which are listPd as follows:
(1) All assembly operations; i.e.~ painting, spraying, - .placing, etc., in preparing the composite cutter - structure for the hot-pressing operation ~Step - : No. 1~ in Table 1) are performed at or nea~ room . temperatuxe Thus, problems associated with thermal porperty differences or low s-trength, unconsolidated -. _ . . 7-:. /. .
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sta-te of the composite cone prior to hot densif ica-tion, are avoided Repair work, geometrical or dimensional control, and in-proc~ss handling are greatly simplified.
(2) Application of powdered metal or alloy or metal compound surface layers, using ~012tile binders, such as cellulose acetate, corn starch and various distilled products, pro~ide stur2y powder layers strongly held together by the binding agen~, thus adding to the green strength OL the to-tal unconsolidated cone structure. This ma~es i~
easy to control surface layer thickness, handling of ~he assembly in processing and pro~iaes mechanical support for the carbide inserts.
(3) Low-temperature application of a,orementioned - surface layers avoias pit~alls a~soclated with high-temperature spraying o pow~ers (4) The proposed schemes in every case produce a near-net-shape product, greatly reducing the labor-intensive machining operations re~uired in the conventional conical cutter proauction, - . , . ~ _ ; . r, . . .
' ' CO~E MATERIALS
' Various sec~ions ~f the:cone cross,section; ha~e been identified in Figure 2, each re~uiring dirLerent enginee~ing properties to best function in service. Conseq~len-tly, materials for each section should be selected separately.
In~erior core piece 11 should be mad~ OL an allo~
possessing h1gh strenc~th arld toughness, and pre~era~ly xecluire thermal trcatments beLow 170~F (to reduce aama~e due to coolincr stresses~ to impart its desired rnechanical prop-rties S~lch ~2~ 3 restrictions can be met by the following classes of materials-tl) Hardening grades of low-alloy steels (ferrous base) with carbon contents ranging nominally between 0.1 and 0.65%, manganese 0.25 to 2 0%, silicon 0.lS to 2.2~, nickel -to 3.75%, chromium to 1.250, molybdenum to 0.40%, vanadiwn to 0.3 and re~ainaer substantially iron, total o~ all : . . other elements to be less than 1.0~ by weight.
(2) Casta~le alloy steels having less than 8~ total alloying element content; most typically ASTM-A148-80 grades . . (3) Ultra-high strength steels most specifically known i- .s., in the industr~ as: D-6A, H-ll, 9Ni-~Co, 18-Ni - : maraging, 300~M, 4130, 4330 V, 4340. These ste~ls 15 . nominally have the same levels of C, Mn, and Si , . ~
. as do the low-alloy steels described in ~13 above . However, they have higher contents of other alloying ; elements: chromium up to 5.0%, nickel to 19~0%r . . . molybdenum to 5 . 0 ~, ~anadium to 1.0~, cobal~ to 2~ 8.0~, with remaining su~stantially ironr a~d all -. other elements totaling less than 1~0~.
~3 (Ferrous) powder m~tal s-teels wi ~h nominal chemistries falling within: 79 to 98% iron, 0-20~ copper, 0 . 4 to 1. 0 caxbon, and 0 . 4 . 0% nickel~
~5) Age hardenable ~nd martensitic stainless steels whos~ compositions fall into the limits described in (3) above, except tha-t they may have chromium up to 20~, aluminum up -to 2~5%, tita~ium up to 1 5~or copper up -to 4.0~, and colu~b:ium plus tant~lum up to o. 5s .

In all caseS r the core piece mechaniczl properties .
should exceed the following:
130 ksi ultimate ~ensile strength 80 ksi yield strength

5% ~ensile elongation 15~ reduction in area 10 ft~lb (izod? impact s~reng~h Wear-resistant ex-kerior skin 19, which may have a thic~n~ss wi-~in 0.01 to n . 20 inch xange, need no. be uni~orm in thickness. Materials suitable fo~ ~he cone ex~er;or include:
(1) ~ composite mixture of particles of re~ractory hard compounds in a binding metaI or allo~ where ~he refrac tory hard compounds h~e a micro-hardness . . of higher than i,OOO~g/mm2 ~50-100 g ~esting load), 1~ and a melting poin~ o~ 1600aC or higher in their commercially pure forms, and where the ~inding metal or alloy may be ~hose based on iron~ nickel, cobalt or copper, Examples of such xefrac~ory . . - -~ . i hard compounds include car~ides, oxi~es, nitri~es - and borides (or their.soluble mix.ures~of the ...... :
~i, W, Al, ~, Zr, Cr, MOr Ta, ~b an~ ~f, . - -~
~2j Specialty tool steels, readily available in powder form~ having large amounts of strong carbia2 formers such as Ti, ~, Nb, ~o, W and Cr, and a c~rbon con.en-t highe~ than 2 0~ by we~gh-~
(3~ ~arafacing alloys based on transi.ion elemen~s Fe, Ni, or Co, wi,h ~he ~ollo~lng gener~l chemistry ranges:

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Cobalt .Nickel Iron Base Base Base Chromium 25-30%(*1 10-30~ 0-Z7%
Carbon 0.1-3~5% 0~4-3.0~ 0 1~4 0~
Tungs-ten 4-13~ - 0~5.0~ - -Molybdenum 0-5% 0-17.0~ 0 11 Boron 0-2.5~ 0-5.0~
Iron 0-3.0~ 329~ ~alance Nickel 0 3.0% Balance - ~-1.75%
Cobalt Balance 0-12% --Silicon 0-2.0~ 0-4 5% 0-1.5 Managanes 0~ 0~ . 0-1.0% 0-1.0 (*) percentage by weight (4) Wear-resistant intermetallic (Laves phase) materials based on cobalt or nickel as the p.rimary constituent . and having molybdenum (25-35%), chromiu~; ~8-18%), ; silicon (2-4%~ and carbon 0.08% maximum.
Thrust-bearing 16 may be made o~ any metal or alloy having a hardness above 35 Rc. They ma~, in such cases, have a composite structure wher.e part of the structure is a lubricatirlg material such as molybdenum disulfide, tin, copper, silver, lead or their alloys, or graphite. . . . . .
Cobalt-cemented ~`ungs-ten carbide inserts 17c cutter t2eth 17 in Figure 2, are to be readily available cobalt--tungs-ten.
carbiae compositions whose cobal-t CQntent usually is within the 5-18% range.
Bearing a.lloy 15, if incorpora-ted into the cone c~s a separately-manufactured insert, may ei-ther be a nardenecl or carburize~. or nitrided or borided steel or any one of a number o~ readily available commercial non-.~errous bearing alloys, ~æ~o~

such as bronzes, If the bearing is weld deposited, the material may s-till be a bronze. If, however, the bearing is integrally hot pressed in place from a previously applied powder, or i~ the insert is p.roduced by any o~ the known powder metallu~-~y techniques~ then it may also have a composite str~cture ha~ing dispersed within it a phase providing lubricating properties to -the bearing.

EXA~LES

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~n example for the processing o~ roller cutters includes 10 the steps 1, 3, 5, 6, 7, 10, 11, 12 and 14 provided in Table l A low ~lloy steel composition was blended to produce the final chemical analysis: 0.22~ manganese, 0.23~ molybdenum, 1,84 nickeI, 0.27% carbon and remainder substan-tially iron. The powder was mixed with a very small amount o~ zinc stearate, for lubricity, and cold pressed to the shape of the core piece 11 (Fisure 2~ under a 85 ksi pressure. The pre~o~ was -then sintered for one hour at 2050F to increase its strength.
A slurry was prepared of Stellite No. 1 alloy powder a~d 3% by weight cellulose acetate and acetone in amoun~s adequate to provide the desired viscosity to ~he mix~ure . The - St~llite Mo. 1 nominal chemistry is as follows: 30~ chromium (by weight), 2~5% carbon, 1% silicon, 12.5~ tungsten, 1~ max~num each of iron and nickel with remainder being subst~ntially cohalt The slurry was applied over the exterior surfaces of the core piece using a pain-ter's spa-tula, excepting those.teeth surfaces where in service abrasive wear is desired in order to create self-sharpening effect. Only one side of the teeth was thereby covered with the slurry and hefore the slurry could dry to harclen, 0 08" thick cobalt cemented (6~ cobalt) t~ngs-ten car~id~

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inserts (Fic~ure 4, a) were pressed into the slurry. Excess slurry at the carbide insert edges were removed and in-terfaces smoothed out using the spatula.
A thin layer of an alloy steel powder was similarly applied, in a slurry state, on thrust bearin~ surEaces identifie~
as 16 in Figure 2. The thrust bearing allo~ s-teel was identical in composition to the steel used to make the core piece, except the carbon content was 0~8~o by weight. Thus, when given a hardening and tempering heat treatment the thrust bearing surfaces would harden more than the core piece and provide ~he needed wear resistance.

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An AISI 1055 carbon steel tube ha~ing 0.1" wall thickness was fitted into the radial bearing portion of the core . ... . .
piece b~ placing it on a thin layer o~ slurry applied alloy steel p~waer used for the core piece.
- . . , -- T~e preform assembly, thus prepared~ was dried in an . . -- . . .
oven at 100F for overnight, driving away all volatile constituen~s o~ the slurries used. I-t was then inauction heated to about 2250P within four minutes and immersed in hot ceramic grainr . . .
which was also at 2250F, wi-thin a cylindrical die. ~ pressure o~ 40 tons per square inch was applied to the grain b~ way o~
.. . . .
an hydraulic press. The pressurized grain transmittea the pressure to the preform in all directions. The peak pressure was reached wlthin 4-5 seconds, and the peak pressure was maintained for less than two seconds and released. The die content was emptied,separatin3 the grain from the now consolida-ted roller bit cutter. BeEore the part had a chance -to cool belo~
1600F, it was -~ransferred to a furnace operatinc; ak 15~5F, kept there Eor one hour and oil quenched. To pre~ent oxidation the furnace atmosphere consisted Oe non-oxidizinc~ cracked ~mmonia The hardened part was then tempered for one hour at 1000F
and air cooled to assure toughness in the core.
A sirnilarly processed tenslle test bar when tensile tested exhibited 152 ksi ultima-te tensile strensth, 141 ksi yield strength, 12~ elongat.ion and 39~ reduction o~ are~.
Another test bar which was processed inkhe sam~ man~er as - above, except temper.ed at 450F, exhibi-te~ 215 Xsi ultima-te .
tensile strength, 185 ~si yield strenght~ 7% elongation and 21~ reduction OL ar~a. Thus, i~ is apparent t~a- one may easily develop a desired set o mechanical propertie5 i~ ~he consolidated core piece ~y tempering at a selected -temperature In another example, powder slurry for ~he wear resistant e~terior skin and the thrust bearing surface was prepared using a 1.5% by weight mixture of cellulose acetate with S-tellite alloy No. 1 powder. This preform was dried at 100F .for overnight ins~ead of 250F for two hours, and t~e remaining processing steps were identical to ~he above example ~o visible di~erences were detected be-tween ~he two parts produced by the two experiments. .
In yet another exampler radial bearing alloy was ~ ., ~ : i affixe~ on the interior wall o the core through the use o a nickel powder slurry similarl~ prepared as abov~. Once again the bond between the radial bearing allo~ and the core piece was extremely strong as determined by separatelY conductea bonding experiments ;
HER PERTINE~lT INFORMrr~TIO?J

The term "composi-te" is used both in ~he micro s~ruc~ural sellse or from an enyineerin~ sense, whichever is more --~0--appropriate. Thus, a material made up of discrete fine phase(s) dispersed wi-thin another phase is considered a composite of phases~ while a structure made up of discrete, rela-tively large regions joined or asser~led ~y so~e means, -toge-ther is also considered a "composi-te." An alloy composed o~- a mixture of carbide particles in cobalt, would micro-structurally be a composite layer, while a cone cutter composed of various distinct layers, carbide or o-ther inserts, would be a composite part~
The term "green" in Ta~le 1, line 2, referes to a .io state where the powder metal part is not ~et ful}y den5ified but has sufficient strength to be handled wi.thout chipping or breakage.
Sintering (the same table, line 3) is a process by ~hich powdered (or otherwise) materlal is put in intimate contact and heated ~o cause a m~tallurgical bond be-tween them.
This invention introduces, for the first -time~ ~e ~ollowing novel features to a drill bit cone:
(13 A "high-temperature - short-heating cycle" means of consolidation of a composite cone into a nearly inished product, saving substantial labor time.

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and allowing the use of multiple materials tailored to mee-t localized demands on their properties.
(2) Application o~ material layers at or near room tempera-ture, which eliminat:es thermally-induced structural damage if a the~nally-activatea process were to be usedO
(3) A "hiyh--temperature - high-pressure - short--time"
processing scheme, as outlined in Figure 3, where time~temperature dependent diffusion reactions are su~stantially reduced.

(4) A rock bit conical clltter having a hard, wear-resistant exterior skin and an interior pro~ile which may consist oE a,layer bearing allo~ or two . .differen-t alloys, one for each radial and thrust 15 . . bearings; all of which substan~ially surround a - high-strength, tough core piece having protruding . teeth. ~ -(5) A conical cutter same as in Item (4), but having teeth partially.covered on o~e side with an i~sert, pxeferab~y a cobalt-cemented tungsten carbide insert, which is bonded onto the interior core .
p.iece 11 by a thin layer of a carbiae-rich hard alloy similar to those used for the exterior skin 1~. This is illustrated in Figs. 4(a) and 4~c~, and is intended to provide a uniform, hard-cutting edge to tne cutting teeth as the~ wear in downhole service; i.e., selE~sharpening o~ tee-th ~see Fig.
4(c). This is to be contracted with problems of degradation of ~he cuttiny edy- encountered in hardfaced teeth ~see Figs 4~b) and 4~d)~
~6) A conical cutter, as in Item ~5), but having interior bearing surfaces provided hy pre-formed and shaped inserts prior t:o hot consolidation of the composite cone. These inserts may be one or more pieces, at least c~ne o~ w'nich is ~he r2dial bearing piece~ ThI~st bearing ma~ be pro~ided i~ the ~orm oi a single ;nsert~ or two or more inserts, dependi~g on ~ho cone interior l~ design. These varia~ions are illustrated in - Figs. 5(a)--5(d~. Fig. 5(a~ shows on~ insert : . 30; Fig. s(bj shows a second insert 31 c~ering all interior sur~aces, except ~or insert 3n i . ~
~ Fig~ 5(c).shows a th.ird insert 32 combined with . .: :. , , .:
. inse.rt.30 and a moaified secona insert 31'; ana ` Pig. S(d3 shows modi~ied s~cond and third inserts . 31" and 32". . -7) A conical cutter, as in Item ~6~ ~t havi~g interiar bearing inserts 33 and 34 bon~ed ~nto ~ . . .
. 20 .- ~he interior core piece 11 by a ~,~in layer or : , . . ', ! .
iayers 33a and 34a o~ a auctile al10y~ as . : .illustrated in Figure 6.
~8~ A conical outter same as in (5) r ~U'~ i~terior bearings surface is pro~ided by 2 powder metallurgically applled la~er of a bearing allo~, Fig~ l shows a bit body 40, ~hreaded at ~Oa, with concial cut-ters 4l mounted to journal pins ~2, with ball bearings 43 and thrust bearings 44.

Step 3 of -the process as lis-ted in Table ~ is ~or example shown in Fig. 7, the arrows 100 and 101 indicating isostatic pressuriza-tion of both interlor and exterior surfaces o~ the core piece 11. Note that the teeth 17 are in-~egral with the core-piece and are also pressurized. Pressure application is effected for example by the use of rubber molds or ceramic granules packed about -the core and teeth, and pressurized. S-tep 12 o~ the process as listed in Table 1 is for example show~
in Fig. 8. The part as shown in Fig. 2 is e~bedded in hot 10 ceramic grain or par~icula~e 102, contained within a die 103 having bottom and side walls 104 and 105. A plunger la6 ~i~5 within the cylindrical bore 105a and presses do~nwardly on the hot grain 102 in which consolidating force i5 transmit~ea to the part generally indicated at 106. Accordlngly, the core 15 11 all components and layers attached.thereto as referred to above are simultaneously consolidated and bonded togethe~
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' / ' .

Referriny now -to Fig. 9, drill bit bo~ 200 (typically of hardened steel) includes an upper thread 201 threadably attachable to drill pipe 202. The lower extent of the body is enlarged and flu-ted, as at 204, the flutes having outer surfaces 204a on which claddiny layers 205 are Lormed, in accordance wi-th the invention. The consolidated cladding layer 205 may for example consist of tungsten carbide formed from metallic powder, -the method of application including the s-teps:
a) applying to the body means a'mixture of:
i) metallic powder ' .
ii) fugitive organic binder iii) volatile solvent b) drying the mixture, and c) burning out the binder and solvent at elevated temperaturev, d) and applying pressure to the powdered me-tal to consolidate same on the body means.
In this regard, the binder may consist of cellulose acetate, and the solvent may consist of acetone. Representative formula,tions are set forth below:

Ingredient of flu_d mlx-ture Weight percent range tungsten carbide powder ( 0.001 mm to 0.100 mm) 30 to 60 cellulose acetate 1.0 to 5.0 acetone As needed Steel Powder (as binding metal), _ 20 to 70 ~æss~o~

O-ther usable powdered metals include Co-Cr-W-C alloys, Ni-Cr-B alloys _ ; other usable binders include waxes~ polYvinyl-butYral (PVB) ; and other usable solvents include_dibu-tyl Phthalate _DP~) Typically formulations are as follows:

EXAM LE _ Stellite Alloy No. 1 powder ~ - 97 -to 98 wt.%
(O.Q01 to 0.050 mm) Parafin wax --------------------------- 2 to 3 wt.%
(Stellite is a trademark of Cabot Corporation, KoXomo Indiana, and Stellite No. 1 alloy has a nominal composition by weight of 30% Cr, 12.5% W, 2.5% C and remaining substantially Cobalt).

Deloro Alloy No. 60 --------------~--- 90 to 95 Wt.%
Polyvinyl-butyral ~PVB) --~ -------- 3 to 6 Wt.%
Dibytyl Phthalate (DPB)--------------- 2 to 4 Wt.%

Fig. 9 also shows annularly spaced cutters 207, and a nozzle 208 (other bodies) bonded to the main hody of the bit 200, by the process referred to above. The cuttersare spaced to cut into the well bottom forma-tion in response to rotation of the bit about axis 209; and the nozzle 208 is angled to jet cutting fluid (drilling mud) angularLy outwardlT~ to~ard the cutting zones. Such fluid is supplied downwardly as via the drill pipe 202 and the axial through opening 200a in the bit.
Accordingly, this invention can be used to attach various wear resistant or cutting members to a rock drill bit or it may be used to consolidate a rock bit in its totality integral with cutters, grooves, wear pads and no~zles. Other types of rock bits, such as roller bits,and shear bits, may also be manufactured using this invention.
Figs. 10-12 show application of the invention to fabrication of drill string stabilizers 220 and including a ..
sleeve 221 comprising a steel core 222, and an outer cylindrical member 223 attached to the core, i,e. at interfacè 224. Powdered metal cladding 225 (consolidated as per the above described method) is formed on the sleeve member 223, i.e. a-t the sleeve exterior, to define wear resistant local outer surfaces, which are spaced apart at 227 and spiral about central axis 228 and along the sleeTJe length, thereby -to define T~ell fluid circulation passagesin spaces 227. Also, other bodies in the form of wear resistan-t pads 229 are ~oined (as by the process to the sleeve member 223, and specifïcally to the spiraling lands 223a). Fig. 12a, for example, shows how the consolida-ted metal interface 230 forms between a pad 229 (or other metal body) and land 223a (or one metal body). See for example ceramic grai 23] T~ia which pressure is exerted on the mixture tpowdered ~2S~063 metal and dried binder) to consolidate the powdered metal at elevated pressure (45,000 to80,000 psi) and temperature ____ I
( 1950 F to 2250 F). The powdered metal may comprise hard, wear resistant metal such as tungsten carbide, and steel ).
Fig. 13 shows applicatlon of the method of the invention to the joining o~ two (or more) separa-te steel bodies 240 and 241, at least one of which is less than 100~ dense.
Part 241 is placed in a die 242 and supported therein. A
layer of a mixture (powdered steel, binder and solvent, as described) is then applied at the interface 243 be-tween parts 240 and 2~1, and the parts may be glued together, for handling ease. The assembly is then heated, (1000F -to 1200F) to burn out the binder (cellulose acetate). Ceramic grain 244 is then introduced around and within the exposed part of body 240, and ! pressure i5 exerted as via a plunger 245 in an outer container on cylinder 246. The pressure is sufficient to consolidate the powdered metal layer between parts 240 and 241, and also to further consolidate the part or parts ~240 and 241) which was or were not 100% dense. The parts 240 and 241 may be heated to temperatures between lgO0 F to 2100 F to facilitate the consolidation.
The invention makes possible -the ready interconnection and/or cladding of bodies which are complexly shaped, and otherwise difficult to machine as one piece, or clad.
To demonstrate that separately manuEactured metal shapes can be joined without canning and without special joint preparation, slugs measuring 3/4 inches in height were prepared and joined The common approach in these experiments involved the use o~ a powder rnetal-cement mixture as disclosed which when applied around the joint allowed -the two slugs to be joined to be easily handled during processing.
The first experiment involved the use of two slugs of cold pressed and partially sintered (-to 20% porosity) 4650 powder. The dry cut surfaces of the slugs were put together after partial applica-tion of 416 stainless s-teel powder-cementing mixture on the interface. The powder-cement mixture acted as - a bonding agent as well as a marker to located the interface after consolidation.
The cementing mixture at and around the joint was allowed to dry in an oven at 350F. I'he assembly of two 4650 slugs were then heated in a reducing atmosphere (dissociated ammonia) to 2050F for abou-t 10 minutes and pressed in hot ceramic grain using 25 tons/sq. in. load at 2000F. Visual examination ol the joined slugs indicated complete welding had ta~en place. Microstructural examination s'nowed no evidence of an interface where no 416 powder markers were present, indicating an excellent weld.
A similar experiment wlthout the use of 416 powder as marker at the interface, showed complete bonding of the two 4650 slugs.
III another experiment two wroug'nt slugs of the ~lSl 1018 carbon steel were joined by using a layer of ~650 alloy steel powder in be-tween the two pieces. The heating and hot pressing procedure was the same as above. The joint obtained indicated 100~ bonding and could easily be loca-ted in the microstructure due to the difference in response to etching solution by the two steels.

A Rockwell-C hardness inden-tation, made under 150 kg load, righ-t on the interface between 1018 and ~650 alloys drama-tically demons-trated the strength of the bond be-tween these two ma-terials. No separation occured aEter -the indentation.
In fact, a tensile bar fabricated from a bar (formed by joining pressed and partially sintered ~650 and 416 s-tainless steel slugs) when pulled in tension, broke within the weaker member, 416 stainless, and the joint interface remained undisturbed.
The break occured at 73,400 psi near the annealed tensile strength of wrought 416 stainless steel.
Experiments to date have shown that metal parts having 100~ dense structures with wrought metal mechanical properties can be manufactured without canning, by utilizing heating-pressing cycles that last only few minutes. The process is also capable of producing complex shaped parts that cannot be produced by closed die pressing. This can be ... .
~ accomplished through joining of separately produced shapes having the following processing histories.
1. Cold pressed powder preform 2. Cold pressed and lightly sintered powder pre~orm 3. Wrought or cast preform 4. Powder metal coating applied with a cement Structures highly complex in shapes can be produced through joining of such preforms in any combination.
In addition, each piece being joined may consist o~
a different alloy. Experimen-ts indicate that there should be no major problems in bonding alloys based on iron including stainless steels, tool steels, alloy and carbon steels. Alloys belonging to other alloy systems, i.e., those based on nickel, cobalt and copper, may also be joined in ~ny combina-t:ion, ~3~-provided care is taken to prevent oxidation a-t the interface.
The join-t bond strength appears to be at leas-t equal to the strength of the weakes-t component o~ the structure.
This is much superior to the join-t strengths obtained in any of the conven-tional cladding/coating processes, i.e., p]asma spraying, chemical or physical vapor deposition, brazing, Conforma-Clad process (Trademark of Imperial Clevite), d-gun coating (Trademark of Union Carbide). As a cladding process, therefore, the present invention is superior in terms of interfacial bond strength.

As a ~oining process, the bond strenghts obtainable are comparable to those typically obtained by fusion welding, except tha-t there is practically no dilu-tion expected at the interface due to short time processing cycle, and the low bonding temperatures used. Thus, joint properties obtainable by joining appear superior to even the best (low dilution) fusion welding processes such as laser or elec-tron beam welding.

-3l-

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of consolidating metallic body means which includes:
(a) applying to the body means surface a mixture of:
(i) metallic powder, (ii) fugitive organic binder, and (iii) volatile solvent, (b) drying the mixture, (c) burning out the binder and solvent at elevated temperature, (d) immersing the heated body means in a heated granular bed of refractory material within a metal die, and (e) applying a pressure to the granular bed, which transmits the pressure to the body means, until the said metal powder is consolidated and bonded to the said body means.

2. The method of claim 1 wherein said binder consists essentially of cellulose acetate.

3. The method of claim 1 wherein said solvent consists of acetone.

4. The method of claim 1 wherein said powder consists essentially of steel.

5. Body means having cladding consolidated thereon by the method of claim 1.

6. The method of claim 1 wherein said body means comprises multiple bodies joined together by said con-solidated powder metal initially in said mixture.

7. Body means comprising multiple bodies joined together by the method of claim 1 with said consolidated metal powder located between the bodies.

8. The method of claim 6 wherein at least one of the bodies is consoldiated at the same time as said step (e) of claim 1 is carried out.

9. The method of claim 8 wherein at least said one body, prior to said step (e), consists of powdered metal which is not completely consolidated.

10. The method of claim 6 wherein said bodies have rim portions which are joined together by said consolidated powder metal initially in said mixture.

11. The method of claim 6 wherein one of said bodies comprises a drilling bit core.

12. The method of claim 5 wherein said body means comprises a drilling bit core, and said cladding is formed on said core exterior to provide a wear pad.

13. The method of claim 6 wherein one of said bodies comprises a drilling bit core, and another of said bodies comprises a cutter or cutters joined to the core by said consolidated powder metal initially in said mixture.

14. The method of claim 6 wherein one of said bodies comprises a drilling bit core, and another of said bodies comprises a nozzle joined to the core by said consolidated powder metal initially in said mixture.

15. The method of claim 5 wherein one of said body means comprises a stabilizer sleeve adapted for use in a well bore, and said cladding is formed on the sleeve exterior to define a wear resistant local outer surface or surfaces.

16. The method of claim 15 wherein there are multiple of said surfaces which are spaced apart and spiral about and along said sleeve, thereby to define well fluid circulation passages therebetween.

17. The method of claim 6 wherein one of said bodies comprises a metallic stablizer sleeve adapted for use in a well bore with a drill pipe extending therethrough, and another or others of said bodies comprises a wear resistant pad or pads joined to the sleeve by said consolidated powder metal initially on said mixture.

18. The consolidated body means produced by the process of claim 1.

19. The method of claim 1 wherein said mixture is a fluid and is applied to said body means by one of the following:
(i) dipping the body means into said mixture, (ii) painting said mixture on the body means, (iii) spraying the mixture onto the body means.

20. The method of claim 1 wherein the body means has a layer of powder metal consolidated and bonded provided thereon, thereby forming a consolidated cladding on the body means, by the steps recited in claim 1.

21. The method of claim 1 wherein the initial density of the body means is less than 100% of its theoretical density and the said body means is consolidated simultaneously with said step (e) of claim 1.

22. The method of consolidating a metallic body means by joining separately produced metallic body components, as follows:
(a) applying to the joint surfaces on the said body components a mixture of.
(i) metallic powder, (ii) fugitive organic binder, and (iii) volatile solvent, (b) assembling the components to be joined together whereby the said mixture acts as weakly binding adhesive between the component joint surfaces, (c) drying the mixture, (d) burning out the binder and solvent at elevated temperature, (e) immersing the heated assembly of body components, still relatively weakly bonded together at the joint surfaces, in a heated granular bed of refractory material within a metal die, and (f) applying a pressure to the granular bed, which transmits the pressure to said components, until the said metallic body components are bonded together strongly by the consolidation of the metal powder applied to the joint surfaces and by bonding of the consolidated metal powder to the surfaces of the metallic body components, thus creating a metallic body means more complets in shape than the original body components.

23. The method of claim 22 wherein the said metallic body components number three or more.

24. The body means produced by the method of one of claims 22 and 23, wherein said components and the said metal powder used to join the components have dissimilar compositions.

25. The body means produced by the method of one of claims 22 and 23 wherein at least one of the metallic body components being joined has a density less than 100% of its theoretical density initially, and is consolidated simultaneously with said powder metal at the same time as said step (f) of claim 22 is carried out.

26. The body means produced by the method of one of claims 22 and 23 wherein at least one of the body components initially has less than the full theoretical density and consists of powdered metal which is not completely consolidated.

27. The method of one of claims 22 and 23 wherein the powder metal applied to the joint surfaces is partially sintered into a strip prior to being placed in the joint between the body components being joined.

28. The method of claim 22 wherein step (e) is carried out so that the granular, pressure transmitting bed envelopes only a portion of the assembly of metallic body components, the remainder of the assembly being supported by a solid shaped die.

29. A roller bit rolling cutter used in earth drilling produced by the method of one of claims 1 and 22.

30. A shear bit used in earth drilling, utilizing polycrystalline diamond compacts as cutting elements, produced by the method of one of claims 1 and 22.

31. A stabilizer sleeve used in earth drilling produced by the method of one of claims 1 and 22.

32. The method of one of claims 1 and 22 wherein one of the components is a leachable ceramic, and can be chemically removed after consolidation of the body means to provide a predesigned cavity.