US2875043A

US2875043A - Spray-weld alloys of the boron-silicon-nickel type

Info

Publication number: US2875043A
Application number: US576217A
Authority: US
Inventors: Tour Sam
Original assignee: Metallizing Engineering Co Inc
Current assignee: Metallizing Engineering Co Inc
Priority date: 1956-04-04
Filing date: 1956-04-04
Publication date: 1959-02-24
Anticipated expiration: 1976-02-24

Description

United r i tent 2,875,043 SPRAY-WELD ALLOYS 31F Inn SILICON-NICKEL TYPE Sam Tour, :New York, .N. Y., ,assignor to Metallizlng Engineering "Co., Inc., a corporation of New Jersey .NoDrawing. Application April 4,1956 Serial No. 576,217

16 Claims. c1. 75-134) BORON- ticularly for coating materials :applied as a fused :orv welded over-lay on base materials, such as steel or steel alloys.

The elements boron and silicon, when added to nickel or nickel base alloys, act as fiuxer of the alloy and of the "surface to be alloyed during the fusing of thealloy when performing the brazing, welding or coating opera tion. For this reason tluxing alloysf',

One process frequently used for applying fused coatings of 'boron-silicon-nickel alloys is known as sprayweldingjf Spray-welding comprises the steps of first metal spraying thealloy onto the surface 'to be coated,

and second, fusing the coatingin place. The metal spray ing operation can be carried out by any of the known metal spraying techniques, in which the material to be sprayed isfed intoa heating zone whereitis melted or heat-softened and from which it is, in finely divided form,

propelled in molten or heat-plastic condition onto the surface to be coated. The material being'fed to the heating zone-maybe in theform of a rod or in the form of a powder, or in some cases,in the form of a powder bonded together by a plastic material'to form a wire, said plastic material being of 'a :nature such that it disintegrates in the heat of the flame, releasing the metal particles. In metal spraying methods where the material is fed intheform of a rodorwire, the tip of the wire is melted in the 'heating zone and suflrcient energy is applied to-the tip of the molten wire by a blast of air or othergas, to causethe'moltenmetalat the tipto subdivide into ja ifine sprays t After coatingshave been applied bythe metal spraying process, they are thereafter fused inthe-carrying out of the spray-welding process. Such fusing maybe "done in a furnace or, alternatively,by means of heating torches applied directly to the coated surface.

, .Only" alloys which have ,certain ,-properties are suitable and practical for the spray-weld process. Someof the properties required for such alloys are: r f(-l) he property of a melting point appreciablybelow the melting point of the base to which they ateapplied,-

(*2) Thepropertyofwetting'thesurfaceto which they are applied'tusually steel); t r 1 ,(3) The'property'ofhaving-a relativelyiwideviscous fluid range with respect totemperature variationyso that 'coatingswill notrunor drip during the fusing-operation; it

{4) The property of having a relativelylowsurface such alloys are known as self- 2,875,043 p tented Feb. 24, 1959 tension to avoid retraction from edges during the fusing operation; t

(5) The property of having sufficient plasticity at temperatures below but near the melting point, to avoid undue cracking due to shrinkage during freezing;

(6) The property of having sufiicient ductility or toughness .to avoid cracking due to temperature vari ations during cooling; t

(7) The property of forming ,flnoxide-dissolving slag separable from the molten metalto remove the oxides therefrom, since such oxides formed during spraying or fusing interfere seriously with the coalescence during fusing and adversely afiect the "physical properties of the fused coatings;

ice

(8) The property of resisting corrosive attack of various environments. f a

The best self-fiuxing alloysfor the spray-welding process that have heretoforelbeen known comprise nickel base alloys of the boron-silicon type and of the boronsilicon-chromium type.

-The extent to which thehbase spray-welding properties of the boron-silicon-nickel baseralloy can remain essentially unaifected'isexemplified by the fact that they may contain from 0% up to20% Cr by weight of total alloy. This component imparts increasing corrosion and oxidation-resistance properties without interfering with or displacing the essential in (1) to (7) above. r

On the other hand, suchelement as carbon may be present as an impurity or as a desirable component to increase, for instance, the hardness of-the spray-welding alloy. The upper limit of C content, however, is dictated by the fact-that excessive amounts willimpart too high a degree of brittleness to the alloy, thereby interfering with the propertyof ductility as set forth in (6) above. Another frequentlyoccurring component of these spray-welding boron-silicon-nickel; base alloys is iron, which should notbe normally present in amounts exceeding 10%, and preferably not in amounts exceeding 5% by Weight of the total-alloy.

A typical spray-weld.alloy of the boron-silicon-nickel type, as an example, c0nsists0f10.7l% carbon, 13.5 4.5% silicon, 2.75-3:75% boron, 3--5% iron, and 0ptionally an adidtional 16-48% "chromium and nickel making up the balance. 1

Such heretofore known alloys however have metthe property requirements (1) to 8) above only to a very limited extent. If the alloysare designed to meet some of the requirements, sthey tend not ,to meet ,other reproperties of thealloy enumerated quirements. .For instance, analloy of the type given in the above example has satisfactory properties with respect tomeltingpoint, wetting and slagging, but has the objection that the plastic or viscous fluidity range is not sufficiently wide, the fluidity too great, the surface tation is due,amon g otherjeasons, .to the heat-resistive nature of the alloy or-the relativehigh fluidity, or, some combination of 1 these properties which 1 is not altogether understood, yet for many purposes; heavier coatings would be desirable.

The relative ,narrowness-of;thetyiscous fluidity range t of a the prior -boronsilicon nickel ,base ,spray- 'welding ,al- 7 loys is a serious deficiency. Though that rangeisior these alloys about 75 -100 F. it is, under conditions I of torch-heating, difficult and sometimes impossible to uniformly operate within that range and requires skill and experiencedoperators. V n

One object of this invention is to provide an alloy of the boron-silicon-nickel base type for use in the spray-welding process which overcomes these objections of the heretofore known alloys.

It is a further object of the invention to provide such an alloy substantially meeting all .of the requirements of (l)-(8) above, to a greater and more satisfactory extent than hitherto possible.

It is a further object of this invention to provide a self-fluxing alloy which has superior properties, for use in the spray-welding process as enumerated above.

It is a further object to provide an alloy for the spray-welding process which has the property of greater toughness and improved ductility at temperatures just below its melting point. 1

It is a further object of this invention to provide a boron-silicon-nickel base type alloy for use in the spraywelding process which has the property of a viscous fluid range which is wider than that of hitherto known alloys of this type.

It is a further object of this invention to provide an alloy for use in the spray-welding process which has relatively low surface tension in the molten state.

It is a further object of this invention to provide an alloy for use in the spray-welding process which has the property of relatively high resistance to cracking due to temperature variations.

It is still a further object of this invention to provide an alloy of greater resistance to corrosion attack.

These and other objects of this invention will become more evident in the light of the followingdescription.

An alloy for use in the spray-welding process in accordance with this invention comprises a nickel base alloy of the boron-silicon type, containing additionally from 3% to 8% copper, and preferably from 5% to 6% copper, and from 3% to 10% molybdenum, and preferably from 4% to 5%% molybdenum. All percentages herein mentioned are by weight of total alloy.

Spray-welding alloys in accordance with the invention may thus comprise Si: 1-6% and preferably 4-5%; B: 1-6% and preferably 3.54.5%; Cr: ,0-20%; Cu: 3-8% and preferably 5-6%; M: 340% and preferably 45-55%; balance Ni plus impurities. What has been said above in connection with the prior art alloys of the boron-silicon-nickel type regarding impurities and/or additives and especially carbon and free iron, applies equally to the alloys in accordance with the invention.

Typical component ranges of alloys in accordance with the invention are exemplified in the following table:

TABLE 1-5 4-5 4-5 4-5 a. 54. 5, 1-6 a. -4. 5 a. 5-4. 5 a. s4. 5 2.15-s. 75 3-8 5-5 5-6 5-5 3-10 a 5-5. 5 4. 5-5. 5 4. 5-5. 5 4. 5-5. 5 0-20 8-12 15-18 16-18 1 0-1 0-0. 2 04!. 2 0-0. 2 0. 7-1 0-5 0-5 0-5 0-3 0-5 Balance in all cases Ni.

When an alloy in accordance with this invention is usedv fplastic range" and-lowfluidity contribute to this char- 'tively high resistance to V 4 I acteristic. This slushy condition of the new alloy,

7 however, is very pronounced and makes it possible to build up and fuse coatings of much greater thickness than with any previously known alloys.

The new alloy in accordance with this invention has, to a much greater degree than previous alloys, the property of low-surface tension during the fusing operation of the spray-welding process. This property manifests itself by the tendency of the coating to lie flat on its upper surface and to avoid rounding over the edges of the surface and also to avoid lifting up and away from the edges of the surface. In carrying out the spray-welding process, it is very important to avoid these tendencies of rounding away from the edges and of lifting at the edges since the objective of the coating process is to provide an even coat over the surface. In many cases, the coatings are finished such as by grinding, and in such cases, it is important that the coating material be applied evenly over the surface and that it reach to and remain as nearly square as possible, with the edges, so that the entire surface will clean up by the grinding operation. As an example, suppose that the head of a small valve is to be coated, the head representing a disc approximately. /5" in diameter, and that it is to be coated to a thickness of A Any previously known alloy would tend to draw away from the edge, which in this case is the periphery of the disc, with the metal drawing toward the center of the disc in its attempt to form a more nearly spherical surface. The result of this would be that excessive grinding would be required at the center, and that it would be impossible to clean up to the edges with a coating anywhere near to a thickness of If the average amount of metal ground off the surface, for instance, were ,6 then it would be expected that the surface would not be ground at all to within about A of the edge. This condition is avoided almost entirely by the new alloy in accordance with this invention. In the case of the example just cited, it would I be possible to apply a coating of approximately 56 which would lie so nearly flat during and after fusing that it would be possible to grind off approximately ,66 to give a finished coating thickness of A and the coating would clean up all over, to within a few thousandths of an inch of the edge. e

The alloy in accordance with this invention has a relaheat-cracking, which manifests, itself in its avoidance of cracking in places upon cooling. Where materials with relatively poor heat-cracking resistance are used, small hairline cracks frequently develop in the surface of the coating and sometimes theseeracks extend through the coating and even form major fractures. These cracks can, to some extent, be prevented by limiting the use of the method to thin coatings and by taking special precautions during cooling, such as by insulating the parts with asbestos or by keeping them in a furnace while the furnace is slowly cooling off over a period of hours. The new alloy, in accordance with this invention, is much less critical to the formation of cracks than any previously known alloys. This characteristic of the coating helps prevent distortion of the base material and the new alloy is superior in this respect.

The following example illustrates the use of an alloy in accordance with this invention:

H I, Example 1 J One alloy in accordance with this invention has the following analysis: p Percent Nicket alance setters weldingoperation by grit blasting with a conventional blast machine, in which the grit is blown forcibly against the surface of the shaft by means of compressed air, using S. A. E. 6-16 crushed steel grit and a blast air pressure of 100 p. s. i. for a few minutes, sutficiently to roughen and thoroughly clean the surface to be coated. A steel key, A" square, is fitted into the keyway of the shaft before blasting.

A coating of as thickness of the alloy is metal-sprayed in conventional manner over the entire shaft section to be coated while the shaft is rotated in a lathe. The key is then removed by grinding away the edges of the sprayed coating adjacent the key and tapping the key out of the keyway.

While rotating the shaft in a lathe, the shaft is preheated, using a conventional oxy-acetylene heating torch over the entire coated section, to a temperature of approximately 1000" F. The torch is then concentrated at one end of the coated section while the shaft is still rotating, so as to raise the temperature of a small band of the coating. As the coating fuses, the torch is gradually moved along the coated section of the shaft so as to successively fuse each small band of the coating until the entire coating has been fused. The heating is then stopped and the shaft allowed to cool in air and without any attempt at controlled cooling or heat-insulation.

The coated end of the shaft is then ground to a diameter of approximately 2%,". The coating will shrink about 20% during fusing from the original sprayed thickness of Va". This will still leave sufiicient finish allowance for grinding the coating to a finished thickness of approximately on a side of the shaft.

The coating thus applied will be found to be completely finish-ground on the diameter, have a relatively small radius on the corner at the edge of the keyway, be firmly adherent at the edges of the keyway, as well as elsewhere, and be free from cracks in its entire surface.

Other spray-weld alloys, differing in specific composition from the above sample alloy but corresponding in their analysis to the ranges herein claimed, may be substituted in the above example to obtain corresponding results.

Another specific example of my spray-weld alloys is:

Example 2 Element: Percent C 0.8 Si 4.0- B 3.5 Mo 1 5 Fe 2.5 Cu 5.3 Cr 16.0 Ni

Another specific example of my spray-weld alloys is;

Balance silicon type consisting of 1-6% nausea-a. atte pt of as spray-wen alloys 1.:

Example 4 Element Percent C 9 02 Si 3.25 B 33.00 Mo 4.75 Fe 2.25 Cu 5.0 Cr 10.5 Ni Balance course be understood that the alloys made in accordance with my invention may also be sprayed from a wire or rod using a conventional so-called wire-type metal spray gun.- The alloys may be present in wire form, either as such or by way of finely subdivided material bonded together with a plastic agent which will disintegrate during the spraying operation. Many of the sprayweld alloys in accordance with the invention cannot be properly drawn into wire form and may then, however, be cast into rods of suitable length in lieu of compounding the same into a plastic bonded wire. Thus the specific alloy used in accordance with the above examples may be sprayed. from a wire-type gun in the form of a rod or such plastic wire, the spray metal coating being thereafter treated the same as specified in the examples, obtaining similar results.

The foregoing specific description is for purposes of illustration and not of limitation and it is therefore my intention that the invention be limited only by the appended claims or their equivalents wherein I have endeavored to claim broadly all inherent novelty.

I claim:

1. A spray-weldable alloy of the boron-silicon-nickel type containing at least 40% nickel, l-6% boron and silicon in amount up to about 6% having an additional component consisting of 38% Cu and 3-10% M0 by weight of total alloy and possessing a range of viscous fluidity of at least F.

2. The alloy in accordance with claim 1 in which said component consists of 5-6% Cu and 4;5-5.5% M0 by weight of total alloy.

3. The alloy in accordance with claim 1 in which the same contains 4-5% Si, 35-45% B, and 8-20% Cr by weight of total alloy.

4. The alloy in accordance with claim 3 in which the same contains 15-17% Cr by weight of total alloy.

5. A spray-weldable alloy of the boron-silicon-nickel type essentially consisting of 0-l.5% C, l-6% Si, 1-6% B, 0-10% Fe, 0-20% Cr, 38% Cu, 3-10% Mo and at least 40% nickel by weight of total alloy, said alloy having a range of viscous fluidity of at least 100' F.

6. The alloy in accordance with claim 5 in which said carbon content does not exceed substantially 1% by weight of total alloy.

7. The alloy in accordance with claim 6 in which said iron content does not exceed about 5% total alloy.

8. The alloy in accordance with claim 7' in which the content of Si is 4-5%, of B is 3.5-4.5%, of Cu is 5-6%, and of M0 is 4.5-5.5 by weight of total alloy.

9. The alloy in accordance with claim 8 in which the szlalme contains from 8-20% of Cr by weight of total a oy.

10. The alloy in accordance with claim 9 in which tlille same contains from 15-17% of Cr by weight of total a oy.

11. A spray-weldable nickel base alloy of the boron- Si, [-676 B, 0-1096 Fe, 0-2076 Cr, 3-8% Cu, 3-l0% M0 by weight of total alloy, the balance being nicke by weight of 12 The. alloy in accordance with claim 11 in which the same contains 0-10% C and 0-'-5% iron by weight of total alloy.

13. The alloy in accordance with claim 12 in which the same contains 4-5% Si, 3.5-4.5% B, 56% Cu, and 4.5 5.5.% M0 by weight of total alloy.

14. The alloy in accordance with claim 13 in which the same contains 820% Cr by weight of totalalloy.

15. The alloy in accordance with claim 14in which the same contains 15-17% Cr by weight of total alloy.

r a a w F i R fgrei ces cited'in the file of this patent a UNITED STATES PATENTS 1,203,180 f Brix'.i Oct. 31, 1916 2,636,818 Low Apr. 28, 1953 i0 2,755,183 'Cape July 17, 1956 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,875,043 February 24, 1959 Sam Tour It is hereb$ certified that error appears in the-printed specification of the above "numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line '72, for "2,0" read 2.0 column '7, line 2, for O-10%" read Ol% Signed and sealed this 9th day of June 1959.

(SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Attesting Officer Commissioner of Patents

Claims

1. A SPRAY-WELDABLE ALLOY OF THE BORON-SILLICON-NICKEL TYPE CONTAINING AT LEAST 40% NICKEL, 1-6% BORON AND SILICON IN AMOUNT UP TO ABOUT 6% HAVING AN ADDITIONAL COMPONENT CONSISTING OF 3-8% CU AND 3-10% MO BY WEIGHT OF TOTAL ALLOY AND POSSESSING A RANGE OF VISCOUS FLUIDITY OF AT LEAST 100*F.