CN101614241A

CN101614241A - The mild alloy layer forms device and mild alloy layer formation method

Info

Publication number: CN101614241A
Application number: CN200910163983A
Authority: CN
Inventors: 石渡裕; 青山和夫; 远藤伸昭; 田中清贵; 片山仁
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2008-05-27
Filing date: 2009-05-27
Publication date: 2009-12-30

Abstract

A kind of mild alloy layer forms device (10), it comprises parent metal support unit (20) and electric arc generation unit (30), described support unit is a spin axis support base metal (40) rotatably with the central axis (42) in the interior week of parent metal (40), described electric arc generation unit can moving axially along described spin axis, and be fixed on and the inner peripheral surface of parent metal (40) has the position of intended distance, described electric arc generation unit generates electric arc between himself and parent metal (40), this electric arc generation unit generates electric arc (31) between himself and parent metal (40).Rotary substrate metal (40) and the distance between electric arc generation unit (30) and parent metal (40) inner peripheral surface (41) is kept constant in, mild alloy member (50) is formed mild alloy layer (15) by electric arc generation unit (30) fusing to go up at the inner peripheral surface (41) of parent metal (40).The invention still further relates to a kind of mild alloy layer formation method.

Description

The mild alloy layer forms device and mild alloy layer formation method

The cross reference of related application

The application based on and enjoy the preference of No.2008-137366 of Japanese patent application formerly that proposed on May 27th, 2008 and the No.2009-099021 of Japanese patent application formerly that proposed on April 15th, 2009; All the elements of above-mentioned application are hereby incorporated by.

Technical field

The mild alloy layer that the present invention relates to a kind of formation soft (matter) alloy-layer forms device and mild alloy layer formation method, this mild alloy layer is relevant with bearing, this bearing is used for supporting rotor etc., and contact with rotor slidably, this mild alloy layer is also relevant with sealing component, the sealing member contacts with rotor and sealing lubricating oil or steam, above-mentioned parts are used for power (electric power) generation device such as generator and (steaming) steam turbine, and these apparatus and method are used in particular for forming the mild alloy layer that contacts slidably with rotor.

Background technique

Generator, steam turbine etc. have high weight and high speed rotating, thereby rotor wherein is usually by the shaft bearing supporting, to be used for high loading and high speed rotating.Figure 21 schematically shows the cross-sectional structure of typical shaft bearing 300, as shown in Figure 21, shaft bearing 300 has parent metal 301,302 and bearing metal layer 303,304, wherein this parent metal is made also along circumferentially being divided into two halves vertically by structural steel, this bearing metal layer passes through at these parent metals 301, utilize centrifugal casting lining bearing metal on 302 the slip surface side and form, this bearing metal is known as bearing metal (perhaps white metal, Babbitt), and it typically is Sn-Cu-Sb base alloy.Parent metal 301,302 is secured together by bolt 305.The bearing metal that forms bearing metal layer 303,304 has medium hardness and has excellent abrasive, thereby not only uses in power generation arrangement, and is widely used in boats and ships, the naval vessels etc.

Incidentally, the thermal power unit (steam power plant) that is made of combinations such as boiler, steam turbine, generators, thereby moves with stable status as conventional basic operation power for a long time traditionally.Yet in recent years, nuclear power generating equipment has become basic electric power gradually, and under increasing situation, thermal power unit is used to regulate electric power load.Therefore, in thermal power unit, almost all exist the variation of the operation method of repeat switch operation every day.Thereby, being accompanied by the opening and closing of every day, bearing metal layer 303,304 bears cyclic thermal stres.This causes bearing metal layer 303,304 by the generation of thermal fatigue damage phenomenon.

Usually the bearing metal layer that is formed by the lining bearing metal is formed by centrifugal casting.Figure 22 A to Figure 22 E has described the step that forms bearing metal layer by centrifugal casting.At first, the coating layer 311 that provides Ni, Sn etc. to form, with the bond strength (or adhesive strength) of the bearing metal layer on the inner peripheral surface that is used to improve parent metal 310, this parent metal is made by structural steel, it is hollow cylindrical, thereby forms shaft bearing (referring to Figure 22 A).

In this state, it is by heating equipment 312 preheatings, and this heating equipment has electric furnace or gas cooker, thus make coating layer 311 diffuse to parent metal 310 sides and with parent metal 310 integrated (referring to Figure 22 B).

Subsequently, the bearing metal 313 that is in molten state is poured into (referring to Figure 22 C) in the parent metal 310, and parent metal 310 high speed rotating, be pressed against on the inner side surface of parent metal 310 with the bearing metal 313 that will be in molten state, so conquassation defective (referring to Figure 22 D) such as pore for example.Incidentally, at this moment, coating layer 311 and the bearing metal 313 integrated and disappearances that are in molten state.

Behind the casting complete of the bearing metal 313 that is in molten state, cooling water 314 is injected on the outer circumferential face of parent metal 310, with (cooling or the chilling fast) parent metal 310 that quenches, and the bearing metal 313 that is in molten state is solidified, therefore form bearing metal layer (referring to Figure 22 E).

Subsequently, inside and outside side face carries out finishing by machining, and it vertically is divided into two halves then.Therefore, obtain to be similar to the shaft bearing shown in Figure 21.

In above-mentioned shaft bearing, to compare with parent metal 310, bearing metal 313 has significantly bigger thermal expansion coefficient.Therefore, the cooling period after cast, the solidification shrinkage of bearing metal 313 and thermal expansion difference usually cause that bearing metal 313 part from the parent metal 310 peels off.In the described part of peeling off generation, the heat that is difficult to produce in the bearing metal 313 in running is discharged into the outside by transmission of heat via parent metal 310.Therefore, temperature raises and produces bigger thermal stress, and it causes the tired and damage of aforementioned hot.In addition, even when after the centrifugal casting when spraying 314 pairs of parent metals 310 of cooling water and cool off, because the big thermal capacity of parent metal 310, the temperature of bearing metal 313 can not be reduced (cooling rate is about 1 ℃/second) apace, and therefore the refinement for the tissue of bearing metal 313 exists restriction.

In above-mentioned centrifugal casting, bearing metal 313 is cast to following thickness, is the twice to three times (6mm-10mm) of the thickness of the bearing metal layer that finally obtains, and is cut to the thickness of the bearing metal layer of final acquisition then by machining.Therefore, wherein the interior all sides that form the bearing metal layer of micro organization owing to high cooling rate are removed by machining, thereby stay the bearing metal 313 with thick tissue in bearing metal layer.This has reduced the mechanical strength of bearing metal layer, and thereby may be easy to take place above-mentioned thermal fatigue and damage.

As a rule, peel off or improve the method for its intensity as preventing bearing metal layer, for example, JP-A08-135660 (KOKAI) disclose on the inner peripheral surface that a kind of netted fine rule that will be made of metal is fixed on parent metal and subsequently the centrifugal casting bearing metal so that the technology that bearing metal layer combines with netted fine rule.In addition, for example, JP-A 09-010918 (KOKAI) discloses a kind of technology, and this technology is being quenched laser exposure and solidified this layer on the surface of the bearing metal layer that is formed by centrifugal casting and after it melts once more, thus thinning microstructure.

Yet, if adopt above-mentioned routine techniques that netted fine rule is provided on the inner peripheral surface of parent metal, be difficult in the origin that becomes thermal fatigue and damage bearing metal layer slip surface near this netted fine rule is provided.Therefore, very difficult expectation can reach and avoid the interior thermal fatigue of bearing metal and the effect of damage.In addition, the problem that cost of production increases has also appearred, because it need settle and fix the step of this netted fine rule.

In addition, if adopt above-mentioned routine techniques irradiating laser on the surface of bearing metal layer to quench and curing, be difficult to the raising of the bond strength between expectation parent metal and the bearing metal layer to melt the back once more at it.In addition, this Technology Need has laser irradiation step and postradiation machining steps, thereby has brought the problem that increases cost of production.

In addition, the performance of the bearing metal of employing centrifugal casting manufacturing depends on the cool condition after casting condition and the casting to a great extent, thereby has the big dispersiveness of tensile strength, thermal fatigue strength, bond strength etc. and the reliability problems that lacks shaft bearing.

Summary of the invention

Thus, one object of the present invention is to provide a kind of mild alloy layer to form device and mild alloy layer formation method, it can form and contact slidably with rotor etc. and have the excellent bond strength and the mild alloy layer of thermal fatigue strength, and can reduce production costs.

In the present invention, adopt bead-welding technology to form the mild alloy layer of bearing metal etc.The technical background that adopts this bead-welding technology at first, hereinafter will be described.

This bead-welding technology is used as the manufacture method of for example bearing metal of thrust-bearing, and this thrust-bearing has plane structure.Figure 23 A to Figure 23 D illustrates the cross section of welding portion, and to be used to describe the step of conventional bead-welding technology, this bead-welding technology is used as the manufacture method of the bearing metal of the thrust-bearing with plane structure.

In bead-welding technology, as shown in Figure 23 A, electric arc 322 produces between parent metal 320 and welding torch 321, and bearing metal silk 323 is inserted in the electric arc 322, and in fusion bearing metal silk 323, bearing metal layer 324 by built-up welding to the surface of parent metal 320.In addition, in this bead-welding technology, when welding torch 321 or parent metal 320 along continuous straight runs move, repeat built-up welding, thus be parent metal 320 surperficial lining bearing metal layer 324.In addition, the thickness that can pass through the bearing metal layer 324 of one deck built-up welding is about 2mm-3mm, thereby as shown in Figure 23 B, repeats to implement above-mentioned lining step, thereby pile up and this bearing metal layer 324 of lining, produce bearing metal layer (referring to Figure 23 C) thus with predetermined thickness.Then, as shown in Figure 23 D, finish this thrust-bearing by its surface of machining.Compare with centrifugal casting, the bead-welding technology of this routine can improve the freezing rate of bearing metal, thereby can produce the bearing metal layer 324 with excellent tensile strength and thermal fatigue strength.In addition, by selecting suitable built-up welding condition, can on the interface between parent metal 320 and the bearing metal layer 324, form interfacial reaction layer, and can obtain high bond strength.Therefore, no longer need, therefore can reduce cost as the plating process in the centrifugal casting of routine.In addition, by with mobile in the horizontal direction welding torch 321 of constant speed or parent metal 320, bearing metal layer 324 with predetermined thickness can automatically form on the surface of parent metal 320, and this makes and compare with centrifugal casting that the production time can be reduced to 1/10 or shorter.

Thus, the inventor has implemented a kind of test of conventional bead-welding technology, that is, in the time of mobile in the horizontal direction welding torch or parent metal, lining bearing metal layer on the curved surface of the parent metal of shaft bearing.Compare with centrifugal casting, caused higher tensile strength and bond strength like this, but with compare by the thrust-bearing of similar bead-welding technology production, find on the bond strength of bearing metal layer, to exist big dispersiveness.

In addition, the inventor has changed the built-up welding condition, and tentatively produced bearing metal layer, and estimated its bond strength and detected Interface Microstructure between parent metal and the bearing metal in detail by move in welding torch or the parent metal on the curved surface of the parent metal of shaft bearing this bearing metal layer of lining at along continuous straight runs.Figure 24 A to Figure 24 C schematically illustrates the cross section of the interface portion between parent metal 330 and bearing metal layer 331, and above-mentioned accompanying drawing is based on the testing result of the Interface Microstructure between parent metal 330 and the bearing metal layer 331 and provide.

Testing result as Interface Microstructure between parent metal 330 and the bearing metal layer 331, when built-up welding is crossed when low with welding current, on the interface between parent metal 330 and the bearing metal layer 331, do not observe interfacial reaction layer, and bond strength little (referring to Figure 24 A).On the other hand, when welding current is too high, parent metal and 330 and bearing metal layer 331 between the interface on formed interfacial reaction layer 332 with big thickness, and in this case, bond strength also little (referring to Figure 24 B).In addition, when implementing to have the welding of suitable welding current, be formed uniformly the interfacial reaction layer 332 that partly has little thickness, it shows high strength (referring to Figure 24 C).Also find, the thickness of the interfacial reaction layer 332 on the interface between parent metal 330 and the bearing metal layer 331 becomes inhomogeneous, because above-mentioned interfacial reaction layer has thin and homogeneous thickness on the such plat surface of thrust-bearing, and the distance between welding torch and the parent metal has variation slightly on the such cambered surface of shaft bearing.Also find between the nonuniformity of interfacial reaction layer 332 and bond strength, to have good coherence.

Figure 25 schematically illustrates the cross section at the interface between parent metal 330 and the bearing metal layer 331, and wherein this figure is based on adopting scanning electron microscope that the result of the observation of the Interface Microstructure between parent metal 330 and the bearing metal layer 331 is provided.As adopting scanning electron microscope, find that interfacial reaction layer 332 be mainly by the intermetallic compounds of Fe (iron), Sn (tin) and Sb (antimony) formation mutually to the observation of the Interface Microstructure between parent metal 330 and the bearing metal layer 331 and the result of analysis.In addition, also observe the thin segregation layer 333 that mainly constitutes by Cu (copper) in bearing metal layer 331 sides of interfacial reaction layer 332.Particularly, be formed on interfacial reaction layer 332 on the interface between parent metal 330 and the bearing metal layer 331 as the iron of the component of parent metal 330 with as Sn, the Sb of the component of bearing metal layer 331, and clearly, because this reaction, bearing metal layer 331 has high bond strength.On the other hand, clearly, Cu as the alloy compositions of bearing metal layer 331 is come out by segregation between interfacial reaction layer 332 and bearing metal layer 331, because it does not form alloy or intermetallic compounds mutually with Fe, and this has reduced the bond strength of bearing metal layer 331.

Therefore, in order to make bearing metal layer can stably obtain high-adhesion, it is very important controlling above-mentioned interfacial reaction layer to suitable thickness, but the constant welding distance (distance between welding torch and the parent metal) of control is difficult during on as the cambered surface of shaft bearing but not as the weldering of the enterprising windrow in the plane of thrust-bearing.The inventor thinks that this situation causes the inhomogeneous of the interface reaction layer thickness that forms on the interface between parent metal and the bearing metal layer.Thus, the inventor expects, as the weldering of the enterprising windrow of the cambered surface of shaft bearing the time, can to suitable scope, stably obtain high bond strength by the thickness that control is formed at the interfacial reaction layer on the interface between parent metal and the bearing metal layer, thereby produce the present invention.

According to an aspect of the present invention, a kind of mild alloy layer formation device that is used for forming on the inner peripheral surface of parent metal that is cambered surface by bead-welding technology the mild alloy layer is provided, described mild alloy layer is made of mild alloy and contacts with rotor slidably, this device comprises parent metal support unit and electric arc generation unit, described parent metal support unit is that spin axis supports described parent metal rotatably with the central axis in the interior week of parent metal, described electric arc generation unit can moving axially along described spin axis, it is fixed on the position that has intended distance with the inner peripheral surface of parent metal, and between himself and parent metal, generate electric arc, wherein when rotating this parent metal by the parent metal support unit and between electric arc generation unit and parent metal inner peripheral surface, keeping constant intended distance, the arc-melting that the mild alloy member quilt that is made of mild alloy is generated by the electric arc generation unit forms the mild alloy layer thus on the inner peripheral surface of parent metal.

According to an aspect of the present invention, a kind of mild alloy layer formation method that forms the mild alloy layer by bead-welding technology on the inner peripheral surface of parent metal that is cambered surface is provided, described mild alloy layer is made of mild alloy and contacts with rotor slidably, this method comprises that the central axis with the interior week of parent metal is that spin axis supports described parent metal rotatably, rotary substrate metal and can between the inner peripheral surface of the axially movable electric arc generation unit of spin axis and parent metal, keep constant intended distance simultaneously, thereby, on the inner peripheral surface of parent metal, form the mild alloy layer by the mild alloy member that constitutes by mild alloy by the arc-melting that between electric arc generation unit and parent metal, generates.

Description of drawings

The present invention will describe with reference to the accompanying drawings, and these accompanying drawings only are used for schematic purpose, and no matter any being not used in limits the invention.

The mild alloy that Fig. 1 schematically illustrates first embodiment of the invention forms device;

The mild alloy that Fig. 2 A schematically illustrates first embodiment of the invention forms device, and wherein this device has the parent metal support unit of another kind of structure;

The mild alloy that Fig. 2 B schematically illustrates first embodiment of the invention forms device, and wherein this device has the parent metal support unit of another kind of structure;

Fig. 3 schematically illustrates the cross section of parent metal, on this parent metal, utilizes the mild alloy layer formation device of first embodiment of the invention to be formed with the mild alloy layer;

Fig. 4 schematically illustrates the cross section at the interface between parent metal and the mild alloy layer;

The mild alloy layer that Fig. 5 schematically illustrates second embodiment of the invention forms device;

Fig. 6 schematically illustrates the cross section of the sample that uses in tension test;

Fig. 7 schematically illustrates the cross section of the sample that uses in the bond strength test;

Fig. 8 is the chart that illustrates stretch test result;

Fig. 9 is the chart that illustrates the bond strength test result;

Figure 10 illustrates the cross section of the parent metal that is formed with the mild alloy layer on it, forms the conventional bead-welding technology of mild alloy layer when being used to be described in the moving electric arc generation unit;

Figure 11 is for adopting the picture in scanning electron microscope (SEM) cross section at the interface between observed mild alloy layer and the parent metal in embodiment 2;

Figure 12 is for adopting the picture in scanning electron microscope (SEM) cross section at the interface between observed mild alloy layer and the parent metal in Comparative Examples 1;

Figure 13 is the chart that shows the result of tension test and bond strength test;

Figure 14 is the picture in the cross section of the observed mild alloy layer of employing scanning electron microscope (SEM);

Figure 15 is the picture in the cross section of the observed mild alloy layer of employing scanning electron microscope (SEM);

Figure 16 is the mean value chart of situation of change in time that shows the temperature variation of mild alloy layer;

Figure 17 is the picture in the cross section of the observed mild alloy layer of employing scanning electron microscope (SEM);

Figure 18 is for adopting the picture of scanning electron microscope (SEM) observed mild alloy layer cross section in the embodiment 2 who does not have cooling unit, and described cooling unit for example is cooled gas injection unit and parent metal cooling unit;

Figure 19 is the mean value chart of situation of change in time that shows the temperature variation of the mild alloy layer among the embodiment 2;

Figure 20 is the chart that shows the result of tension test and bond strength test;

Figure 21 schematically illustrates the cross section structure of typical shaft bearing;

Figure 22 A is for describing the view that forms the step of bearing metal layer by centrifugal casting;

Figure 22 B is for describing the view that forms the step of bearing metal layer by centrifugal casting;

Figure 22 C is for describing the view that forms the step of bearing metal layer by centrifugal casting;

Figure 22 D is for describing the view that forms the step of bearing metal layer by centrifugal casting;

Figure 22 E is for describing the view that forms the step of bearing metal layer by centrifugal casting;

Figure 23 A illustrates the cross section of welding portion, and to be used to describe conventional bead-welding technology step, this bead-welding technology is used as the manufacture method of the bearing metal of thrust-bearing, and this thrust-bearing has plane structure;

Figure 23 B illustrates the cross section of this welding portion, is used to describe conventional bead-welding technology step, and this bead-welding technology is used as the manufacture method of the bearing metal of thrust-bearing, and this thrust-bearing has plane structure;

Figure 23 C illustrates the cross section of this welding portion, is used to describe conventional bead-welding technology step, and this bead-welding technology is used as the manufacture method of the bearing metal of thrust-bearing, and this thrust-bearing has plane structure;

Figure 23 D illustrates the cross section of this welding portion, is used to describe conventional bead-welding technology step, and this bead-welding technology is used as the manufacture method of the bearing metal of thrust-bearing, and this thrust-bearing has plane structure;

Figure 24 A is the sectional view that schematically shows the interface portion between parent metal and the bearing metal layer, and this sectional view is based on the testing result of the Interface Microstructure between parent metal and the bearing metal layer and provide;

Figure 24 B is the sectional view that schematically shows the interface portion between parent metal and the bearing metal layer, and this sectional view is based on the testing result of the Interface Microstructure between parent metal and the bearing metal layer and provide;

Figure 24 C is the sectional view that schematically shows the interface portion between parent metal and the bearing metal layer, and this sectional view is based on the testing result of the Interface Microstructure between parent metal and the bearing metal layer and provide;

Figure 25 is the sectional view that schematically shows the interface between parent metal and the bearing metal layer, and this sectional view provides based on the result who adopts scanning electron microscope that the Interface Microstructure between parent metal and the bearing metal layer is observed.

Embodiment

Hereinafter, embodiments of the present invention will be described in conjunction with the accompanying drawings.

(first mode of execution)

The mild alloy that Fig. 1 schematically illustrates first embodiment of the invention forms device 10.Fig. 2 A and Fig. 2 B schematically illustrate the mild alloy with the parent metal support unit 20 that is another kind of structural type and form device 10.Fig. 3 schematically illustrates the cross section of parent metal, on this parent metal, utilizes the mild alloy layer formation device 10 of first embodiment of the invention to be formed with mild alloy layer 15.Fig. 4 schematically illustrates the cross section at the interface between parent metal 40 and the mild alloy layer 15.

This mild alloy layer forms device 10 for form the device of the mild alloy layer 15 that is made of mild alloy on the inner peripheral surface 41 of the parent metal 40 that is made of cambered surface by bead-welding technology, and this mild alloy layer contacts with rotor, for example turbine rotor slidably.As shown in fig. 1, this mild alloy layer formation device 10 has parent metal support unit 20 and electric arc generation unit 30.

This parent metal support unit 20 is a spin axis support base metal 40 rotatably with the central axis 42 in the interior week of parent metal 40.Notice that Fig. 1 shows an embodiment, wherein parent metal 40 is by rotating roller 21 from following side bearing.In this structure, parent metal 40 is formed by hollow cylinder, and the central axis of the parent metal 40 of periphery is complementary with the central axis of the parent metal 40 in interior week or is consistent.Therefore, by rotating rotation roller 21 in a predetermined direction, parent metal 40 can be together with the interior Zhou Yiqi rotation of parent metal 40, and this central axis 42 is a spin axis simultaneously.

The structure of noticing parent metal support unit 20 is not limited to this structure, for example, as shown in Fig. 2 A, its outer circumferential face that can be configured to parent metal 40 is kept securely by four supporting arms 22, and this supporting arm 22 is that spin axis rotates with the central axis 42 in the interior week of parent metal 40.Just, the structure of parent metal support unit 20 is not limited especially, has following structure and just can satisfy the demand, and promptly the central axis 42 in the interior week that wherein parent metal 40 can parent metal 40 rotates for spin axis.

In addition, parent metal 40 can have following shape, promptly is divided into two parts, three parts or more part of cylindrical body.Equally, in these structures, parent metal 40 is that spin axis rotates by parent metal support unit 20 with the central axis 42 of the inner peripheral surface of parent metal 40.For example, as shown in Figure 2, the parent metal 40 that has cylindrical body shape divided into two parts can be fixed on the rotating disc 23 by flange part 40c by for example bolt 24 grades, and the central axis 42 in the interior week that this rotating disc can parent metal 40 rotates for spin axis.In this structure, the formation of mild alloy layer 15 begins to carry out to end side 40b from a side end 40a of parent metal 40, and this parent metal 40 has and is divided into two-part cylindrical shape.In addition, when the mild alloy layer 15 that forms also need be at the width on the spin axis direction, this electric arc generation unit 30 moves following distance along the direction of spin axis, this distance is corresponding to the width of the mild alloy layer 15 that forms, and this mild alloy layer 15 begins to form to end side 40b from a side end 40a of parent metal 40 once more simultaneously.Here, when it formed once more, the formation of mild alloy layer 15 was that the temperature of a side end 40a of parent metal 40 reduces from the reason that a side end 40a of parent metal begins.

Electric arc generation unit 30 generates electric arc 31 between himself and parent metal 40, simultaneously by this electric arc 31, the mild alloy member 50 that forms and be inserted between parent metal 40 and the electric arc generation unit 30 by mild alloy is melted, thereby forms mild alloy layer 15 on the inner peripheral surface 41 of parent metal 40.This electric arc generation unit 30 is made of for example welding torch etc.This electric arc generation unit 30 can be along the direction of the central axis in interior week of parent metal 40, be that the spin axis direction moves, and fix, as shown in Figure 3 in the mode that the inner peripheral surface 41 with parent metal 40 has a predetermined separation distance L.Particularly, this separation distance L between the inner peripheral surface 41 of electric arc generation unit 30 and parent metal 40 is retained as constant span L always, though electric arc generation unit 30 when the spin axis direction moves or parent metal 40 also be like this during by 20 rotations of parent metal support unit.

In addition, as shown in Figure 3, preferably, the head portion in the vertical direction of electric arc generation unit 30 is placed downwards, and and the lowest surfaces of the inner peripheral surface 41 of parent metal 40 between have above-mentioned distance L.Particularly, preferably on following part, weld, the lowest surfaces of the inner peripheral surface 41 that this part is a parent metal 40 (lowest surfaces on gravitational direction), thus avoid the fusion mild alloy dirty, form mild alloy layer 15 simultaneously with uniform thickness.Incidentally, this separation distance L can be set to only distance according to constouctional material of welding current and parent metal 40 etc.

Here, preferably, be used to form the second layer of mild alloy layer 15 and the welding current of succeeding layer and be set to less than the welding current that is used for forming the first layer of mild alloy layer 15 on the inner peripheral surface 41 of parent metal 40, the above-mentioned second layer and succeeding layer are by piling up formation on first layer.This mild alloy layer 15 of Xing Chenging has preset thickness by the following method, promptly when forming first layer, on the spin axis direction, swing this electric arc generation unit 30 by parent metal support unit 20 rotary substrate metals 40 and predetermined amplitude and the frequency of employing, pile up on first layer in a similar manner then and form the second layer and further form the 3rd layer, wherein this spin axis is interior all 42 a central axis of parent metal 40.In other words, this mild alloy layer 15 is formed by a plurality of overlay claddings.

Therefore, as mentioned above, the bond strength between first layer and the parent metal 40 can improve by following setting, promptly sets and is used to form the welding current of first layer greater than the welding current that is used to form the second layer and succeeding layer.On the other hand, the second layer and succeeding layer can form by comparing littler welding current built-up welding with the used electric current of first layer.In addition, the welding current that is used for the second layer and succeeding layer by setting is littler, and the temperature that can suppress on the interface between parent metal 40 and the mild alloy layer 15 increases.Thereby, can be suppressed at the growth of the interfacial reaction layer 16 that forms on the interface between parent metal 40 and the mild alloy layer 15, as shown in Figure 4, and avoid the tissue of mild alloy layer 15 to become thick.

Mild alloy member 50 is formed by the bearing metal that is called as white metal, and is formed by the Sn-Cu-Sb alloy usually, and this Sn-Cu-Sb alloy contains Cu and Sb and mainly is made of Sn.The specific embodiment of mild alloy member 50 is the welding wire that above-mentioned Sn-Cu-Sb alloy forms.In addition, as mentioned above, by the test that the inventor did, find that Cu influences the raising of the bond strength of parent metal 40 hardly as the alloy constituent element that forms mild alloy member 50, its be segregated between interfacial reaction layer 16 and the mild alloy layer 15 at the interface and reduce this bond strength.

Thus, preferably, the Cu content that is used on the inner peripheral surface 41 of parent metal 40 forming the Sn-Cu-Sb alloy of mild alloy layer 15 is lower than the Cu content of the Su-Cu-Sb alloy of the second layer that is used to form mild alloy layer 15 and succeeding layer, and this second layer and succeeding layer form by piling up on the first layer of the mild alloy layer 15 that forms on the inner peripheral surface 41.Particularly, the Cu content that is preferably used on the inner peripheral surface of parent metal 40 forming the Sn-Cu-Sb alloy of mild alloy layer 15 is 1wt% to 5wt% (i.e. percentage composition by weight), more preferably 3wt% to 5wt%.Here, being used on the inner peripheral surface of parent metal 40 forming the reason that the Cu content of the Sn-Cu-Sb alloy of mild alloy layer 15 preferably is in the above-mentioned scope is, when Cu content is lower than 1wt%, the reductions such as mechanical strength of mild alloy layer 15, and when Cu content was higher than 5wt%, the segregation of the Cu at the interface between interfacial reaction layer 16 and the mild alloy layer 15 became significantly and reduces bond strength.In addition, be set in the above-mentioned scope by the Cu content that will be used for the Sn-Cu-Sb alloy of formation mild alloy layer 15 on the inner peripheral surface of parent metal 40, ground, top, interface between parent metal 40 and mild alloy layer 15 approaches interfacial reaction layer 16 with being formed uniformly, as shown in Figure 4, can form mild alloy layer 15 simultaneously with excellent bond strength, tensile strength and thermal fatigue strength.

On the other hand, as the Sn-Cu-Sb alloy of the second layer that is used to form mild alloy layer 15 or succeeding layer, for example, preferably use the Sb contain 8wt% to 10wt% and the Cu of 5wt% to 6wt%, the alloy that mainly constitutes by Sn.As the Sn-Cu-Sb alloy of the second layer that is used to form mild alloy layer 15 and succeeding layer, particularly, white metal secondary or white metal two classes (WJ2) etc. have been used.

Next, with reference to figure 1-Fig. 3, will the formation method that the mild alloy layer that adopt first embodiment of the invention forms the mild alloy layer 15 of device 10 be described.

Parent metal 40 is placed on the parent metal support unit 20, and parent metal 40 is with predetermined rotational speed rotation simultaneously.Subsequently, electric arc generation unit 30 is swung on the spin axis direction with predetermined amplitude (for example 5mm to 10mm) and frequency (1Hz to 5Hz), this spin axis is the central axis 42 in the interior week of parent metal 40, and predetermined voltage is applied between electric arc generation unit 30 and the parent metal 40, to generate electric arc 31.Notice that the amplitude of electric arc generation unit 30, frequency and other parameter are set suitably based on welding condition, this welding condition for example is rotational speed, bonding speed of parent metal 40 etc.In addition, the separation distance L between the inner peripheral surface 41 of electric arc generation unit 30 and parent metal 40 keeps constant always.

Subsequently, the top of mild alloy member 50 is inserted in the electric arc 31 with predetermined speed, with fusing mild alloy member 50, thereby forms mild alloy layer 15 on the inner peripheral surface of parent metal 40.At this moment, by the once rotation of parent metal 40, form mild alloy layer 15 on the inner peripheral surface 41 of parent metal 40, this mild alloy layer 15 has the width corresponding to the amplitude of electric arc generation unit 30 on the spin axis direction.In mild alloy layer 15, when the needs of the width on the spin axis direction are wideer, electric arc generation unit 30 moves following distance along the spin axis direction, promptly corresponding to the distance of the amplitude of electric arc generation unit 30, thereby further forms mild alloy layer 15 by similar approach.

Subsequently, the multilayer of mild alloy layer 15, be the second layer with further the 3rd layer first layer that is stacked on the mild alloy layer 15 on the inner peripheral surface that is formed at parent metal 40 by identical method on, thereby form mild alloy layer 15 with predetermined thickness.As mentioned above, for the second layer and the succeeding layer that forms mild alloy layer 15, welding current can be less than forming the used welding current of first layer.In addition, for the second layer and the succeeding layer that forms mild alloy layer 15, the mild alloy member 50 used with forming first layer compared, and can use the mild alloy member 50 with higher Cu content.After adopting said method to form to have the mild alloy layer 15 of predetermined thickness, the surface of mild alloy layer 15 by machining by finishing, thereby obtain final thickness.

As mentioned above, on the inner peripheral surface 41 of parent metal 40, form mild alloy layer 15.Here, on parent metal 40, approach the interface top ground of interfacial reaction layer 16 between parent metal 40 and mild alloy layer 15 and be formed uniformly, as shown in Figure 4, wherein on this parent metal, form mild alloy layer 15 by said method.Preferably, interfacial reaction layer 16 on average has the thickness t of 5 μ m-20 μ m.The reason that this thickness t preferably is in above-mentioned scope is that when this thickness was thicker than or is thinner than this scope, bond strength can reduce.In addition, by making the thickness t of interfacial reaction layer 16 on average be equal to or greater than 5 μ m, can avoid occurring not forming fully the zone of interfacial reaction layer 16.Therefore, interfacial reaction layer 16 can be formed uniformly on the interface between parent metal 40 and the mild alloy layer 15.In addition, by making the thickness t of interfacial reaction layer 16 on average be equal to or less than 20 μ m, can suppress at the interface the continuous segregation of Cu between mild alloy layer 15 and interfacial reaction layer 16.Therefore, can on the inner peripheral surface 41 of parent metal 40, form interfacial reaction layer 16 with high-adhesion.

Notice that in the mild alloy layer 15 that forms with above-mentioned form, for example when a part of deterioration of mild alloy layer 15, this deterioration part is cut by machining removes, and this mild alloy layer 15 can removed formation again on the part by said method.That is to say that mild alloy layer 15 can locally be repaired.

Here, the parent metal 40 that forms the mild alloy layer 15 that device 10 forms of the mild alloy layer with the first embodiment of the invention utilized for example can be used as shaft bearing by lubricant oil supporting turbine rotor and rotor of steam turbo generator, is used for the uses such as seal ring mechanism of hydrogen-cooled but turbogenerator.Notice, the mild alloy layer of first embodiment of the invention forms device 10 and not only can use in above application, on these parts, to form the mild alloy layer, form the mild alloy layer on the part that contacts rotor, for example turbine rotor slidably but also can be widely used in.And the mild alloy layer of first embodiment of the invention forms device 10 for example can also be used for forming slip surface separately on second inner peripheral surface of parent metal as piecemeal watt formula bearing.

As mentioned above, adopt the mild alloy layer of first embodiment of the invention to form device 10, is when spin axis rotate by parent metal support unit 20 with the central axis 42 in the interior week of parent metal 40 at parent metal 40, can form mild alloy layer 15, the separation distance between the inner peripheral surface 41 of electric arc generation unit 30 and parent metal 40 keeps constant always simultaneously.Thus, mild alloy layer 15 can form under such as the identical state of the welding condition of welding distance, thereby for example the thickness of the interfacial reaction layer 16 that forms on the interface between parent metal 40 and the mild alloy layer 15 can be formed uniformly, and remains in the suitable scope.Therefore, the mild alloy layer 15 with high-adhesion can form along the inner peripheral surface of parent metal 40.

(second mode of execution)

The mild alloy layer that Fig. 5 schematically illustrates second embodiment of the invention forms device 10.The mild alloy layer of second embodiment of the invention forms device 10 and forms device 10 by the mild alloy to first embodiment of the invention and be provided for constructing to the parent metal cooling unit 70 that mild alloy layer 15 sprays the cooled gas injection unit 60 of cooled gases and is used to cool off the outer circumferential face of parent metal 40.Notice that because the parts identical with form parts in the device at the mild alloy layer of first mode of execution adopt identical reference character, therefore the explanation that repeats is omitted or simplifies.

As shown in Figure 5, mild alloy layer formation device 10 comprises parent metal support unit 20, electric arc generation unit 30, cooled gas injection unit 60 and parent metal cooling unit 70.

Cooled gas injection unit 60 passes through jetburner, sprays cooled gases 61 as nozzle to mild alloy layer 15, and has jetburner, and the outer circumferential face of described jetburner and parent metal 40 has intended distance.Preferably, be similar to electric arc generation unit 30, this cooled gas injection unit 60 also keeps constant separation distance to place with the inner peripheral surface of parent metal 40 always, even also be like this when parent metal 40 rotations.Thus, the mild alloy layer 15 of formation can be cooled off equably.As the cooled gas 61 that from cooled gas injection unit 60, ejects, can use N (nitrogen), Ar inert gases such as (argons), perhaps air.In these optional gases, for example preferably use inert gas such as N, Ar as cooled gas, with oxidation of avoiding mild alloy layer 15 etc.

The outer circumferential face of parent metal cooling unit 70 cooling parent metals 40, for example, as shown in Figure 5, it is made of water jacket 71 grades of placing contiguously with lower half portion of the outer circumferential face of parent metal 40.Notice that the structure of parent metal cooling unit 70 is not limited thereto, for example, can provide the water jacket that contacts with the whole outer circumferential face of parent metal 40.In addition, this water jacket is provided with supplying mouth 71a that is used for cooling water supply and the exhaust port 71b that is used to discharge cooling water.In addition, parent metal cooling unit 70 for example can be made of nozzle of the outer circumferential face that cooling water, for example water is injected into parent metal 40 etc.That is to say that the structure of parent metal cooling unit 70 is not limited especially, as long as it has the structure of the outer circumferential face that can cool off parent metal 40.Incidentally, preferably, parent metal cooling unit 70 is placed in the mode that the outer circumferential face with parent metal 40 has predetermined separation distance, and it is in towards the position of electric arc generation unit 30 by parent metal 40, thereby cools off mild alloy layer 15 efficiently after the mild alloy layer has just melted.

Next, with reference to figure 5, will the formation method that the mild alloy layer that adopt second embodiment of the invention forms the mild alloy layer 15 of device 10 be described.

Parent metal 40 is placed on the parent metal support unit 20, and parent metal 40 is with predetermined rotational speed rotation.Subsequently, cooled gas 61 is sprayed to the inner peripheral surface 41 that it forms the parent metal 41 of mild alloy layer 15 from cooled gas injection unit 60.In addition, cooling water is provided to parent metal cooling unit 70, with the outer circumferential face of cooling parent metal 40.

Subsequently, electric arc generation unit 30 is swung on the spin axis direction with predetermined amplitude (for example 5mm to 10mm) and frequency (1Hz to 5Hz), this spin axis is the central axis 42 in the interior week of parent metal 40, and predetermined voltage is applied between electric arc generation unit 30 and the parent metal 40, to generate electric arc 31.Notice that the amplitude of electric arc generation unit 30, frequency and other parameter are set suitably based on welding condition, this welding condition for example is rotational speed, bonding speed of parent metal 40 etc.In addition, the separation distance L between the inner peripheral surface 41 of electric arc generation unit 30 and parent metal 40 keeps constant always.

Subsequently, the top of mild alloy member 50 is inserted in the electric arc 31 with predetermined speed, with fusing mild alloy member 50, thereby forms mild alloy layer 15 on the inner peripheral surface of parent metal 40.At this moment, by the once rotation of parent metal 40, form mild alloy layer 15 on the inner peripheral surface 41 of parent metal 40, this mild alloy layer 15 has the width corresponding to the amplitude of electric arc generation unit 30 on the spin axis direction.In mild alloy layer 15, when need be on the spin axis direction wideer width, electric arc generation unit 30 moves distance corresponding to the amplitude of electric arc generation unit 30 along the spin axis direction, further to form mild alloy layer 15 by similar approach.

As mentioned above, quench formative tissue that can refinement mild alloy layer 15 by the mild alloy layer 15 that utilizes cooled gas injection unit 60 and 70 pairs of formation of parent metal cooling unit.Thus, tensile strength and thermal fatigue strength can be improved, and the growth of interfacial reaction layer 16 and the tissue growth of mild alloy layer 15 can be suppressed.In addition, can also on the inner peripheral surface 41 of parent metal 40, form mild alloy layer 15 with high-adhesion.In addition, because this mild alloy layer 15 is cooled off apace and solidifies, the mild alloy layer 15 of formation can not flow downward and following, even also be like this when the rotational speed of for example parent metal 40 increases.

Here, preferably, the average cooling rate of mild alloy layer 15 is about 10 ℃ to 50 ℃/second, even and in this scope, average cooling rate is high more, and effect is good more.The preferred reason of the scope of this average cooling rate that adopts is when average cooling rate is lower than this scope, be difficult to the formative tissue of the most appropriate this mild alloy layer 15 of refinement, and it further to cause the growth of interfacial reaction layer 16.The another one reason is when average cooling rate is higher than this scope, and mild alloy layer 15 is fully expansion and solidifying with the relatively poor state that cooperates of base layer, and is easy to produce the defective such as pore.In addition, this average cooling rate means from the maximum temperature of the mild alloy layer 15 (temperature during by arc-melting, for white metal secondary (WJ2), be 450 ℃ for example) be cooled to the rate of cooling of uniform temperature, this uniform temperature be equal to or less than the material that forms the mild alloy layer solidify the beginning temperature, and at this uniform temperature place, the tissue growth of mild alloy layer 15 become no longer significantly (for white metal secondary (WJ2), being 300 ℃ for example).

In the mild alloy formation device 10 of above-mentioned second mode of execution, provided a kind of example that cooled gas injection unit 60 and parent metal cooling unit 70 are provided.But, notice when mild alloy layer 15 can be with above-mentioned average cooling rate cooling, to have that any unit is just enough at least.

As mentioned above, use the mild alloy layer of second embodiment of the invention to form device 10, can form mild alloy layer 15 when parent metal 40 be the spin axis rotation by parent metal support unit 20 with the central axis 42 in the interior week of parent metal 40, the separation distance L between the inner peripheral surface 41 of while electric arc generation unit 30 and parent metal 40 keeps constant always.Thus, mild alloy layer 15 can carry out under such as the identical state of the welding condition of welding distance, thereby the thickness of the interfacial reaction layer 16 that for example forms on the interface between parent metal 40 and the mild alloy layer 15 can be formed uniformly, and remains in the suitable scope.Therefore, the mild alloy layer 15 with high-adhesion can form along the inner peripheral surface 41 of parent metal 40.

In addition, in the mild alloy layer formation device 10 of second embodiment of the invention, provide cooled gas injection unit 60 and parent metal cooling unit 70, so the formative tissue of mild alloy layer 15 can be by quenching and refinement to the mild alloy layer 15 that forms.Therefore, tensile strength and thermal fatigue strength can be improved, and the growth of interfacial reaction layer 16 and the tissue growth of mild alloy layer 15 can be suppressed.This also allows to form the mild alloy layer 15 that has high-adhesion along the inner peripheral surface 41 of parent metal 40.

Hereinafter will bond strength and the tensile strength that the mild alloy layer 15 that adopt mild alloy layer of the present invention to form device 10 formation has excellence be described based on embodiment and Comparative Examples.

(embodiment 1)

In embodiment 1, the parent metal 40 that preparation is made by structural steel, this parent metal is partly simulated shaft bearing, and it has the internal diameter of 381mm, the external diameter of 481mm and 85 ° central angle.Notice that the method for describing in the formation method of this mild alloy layer and first mode of execution is identical, thereby provide following explanation with reference to figure 1.

This parent metal 40 is placed on the parent metal support unit 20, and this parent metal rotates when from one end to the other side built-up welding is finished along the spin axis direction.Subsequently, electric arc generation unit 30 on the spin axis direction with the warble of amplitude and the 3Hz of 7mm, Yu Ding voltage is applied between electric arc generation unit 30 and the parent metal 40 then, and to generate electric arc 31, wherein this spin axis is the central axis 42 in the interior week of parent metal 40.In addition, Ci Shi welding current is 190A.In addition, the separation distance L between the inner peripheral surface of electric arc generation unit 30 and parent metal 40 is remained 7mm consistently.

Subsequently, mild alloy member 50 is inserted in the electric arc 31 with the speed of 40cm/min to 50cm/min, to melt this mild alloy member, thereby form mild alloy layer 15 on the inner peripheral surface 41 of parent metal 40, this mild alloy layer has the width corresponding to the amplitude of electric arc generation unit 30 on the spin axis direction.Here, as mild alloy member 50, used white metal secondary (WJ2).

Subsequently, electric arc generation unit 30 moves distance corresponding to electric arc generation unit 30 amplitudes along the spin axis direction, further forms mild alloy layer 15 by identical method then.

Then, the multilayer of mild alloy layer 15, be that the second layer, the 3rd layer are stacked on the first layer of mild alloy layer 15 by identical method with the 4th layer, this mild alloy layer is formed on the inner peripheral surface 41 of parent metal 40, therefore forms the mild alloy layer 15 of the thickness with 12mm.

Produce sample from the parent metal 40 that produces mild alloy layer 15 by said method thereon, and sample is carried out tension test and bond strength test.Fig. 6 illustrates the cross section of the sample 100 that uses in tension test.Fig. 7 illustrates the cross section of the sample 110 that uses in the bond strength test.

The sample that uses in tension test 100 shown in Fig. 6 is cylindrical member, and this circumferential member is taken a sample on the spin axis direction by formed mild alloy layer 15 and processed.It is 30mm that sample 100 has parallel portion 111 and the length M that diameter is 6mm.Produce 7 this samples 100, utilize these samples 100, at room temperature carry out tension test according to JIS Z2241.Measurement result according to each sample 100 calculates mean value and standard deviation.

The sample 110 that uses in the bond strength test shown in Fig. 7 is cylindrical member, and this cylindrical member is sampled and processing under the situation that comprises mild alloy layer 15 and parent metal 40.This sample 110 is the classification ring-shaped sample, it has the part that is formed by mild alloy layer 15, this part has the diameter Da of 38mm and the inside diameter D b of 24mm, and this sample also has the part that is formed by parent metal 40, and this part has the outer diameter D c of 28.82mm and the inside diameter D d of 12.1mm.Produce seven this samples 110, and at room temperature use these samples to carry out the bond strength test, calculate mean value and standard deviation according to measurement result to each sample 110 according to ISO 4386/2-1982.In addition, adopt scanning electron microscope (SEM) to observe the cross section at the interface between mild alloy layer 15 and the parent metal 40,, thereby obtain its mean value with the thickness of measurement interfacial reaction layer 16.

The result of tension test and bond strength test is shown in Fig. 8 and Fig. 9.In addition, the thickness average out to 12 μ m of interfacial reaction layer 16.

(embodiment 2)

Except the welding current that is used to form first layer among the welding current of the second layer that is used to form mild alloy layer 15 in embodiment 1 and succeeding layer and the embodiment 1 had compared 5% (welding current of 180A) low, the formation method of mild alloy layer 15 in embodiment 2 was with identical in embodiment 1.In addition, be similar to the mild alloy layer 15 among the embodiment 1, the mild alloy layer 15 that forms on the inner peripheral surface 41 of parent metal 40 has four layers, and has the thickness of 12mm.

Take a sample from the parent metal 40 that adopts said method to produce mild alloy layer 15 thereon, and sample is carried out tension test and bond strength test.Notice that the shape of sample etc. are identical with sample in embodiment 1.Method of measurement in the test of tension test and bond strength, measuring condition etc. are also with identical in embodiment 1.In addition, adopt scanning electron microscope (SEM) to observe the cross section at the interface between mild alloy layer 15 and the parent metal 40,, thereby obtain its mean value with the thickness of measurement interfacial reaction layer 16.

The result of tension test and bond strength test is shown in Fig. 8 and Fig. 9.In addition, the average thickness of interfacial reaction layer 16 is 8 μ m.

(Comparative Examples 1)

In Comparative Examples 1, be similar on the surface of thrust-bearing the conventional built-up welding that forms the mild alloy layer and form technology, under the situation of rotary substrate metal not, the swing of electric arc generation unit is also moved in a predetermined direction, thereby forms the mild alloy layer.Figure 10 illustrates the cross section of the parent metal 40 that forms mild alloy layer 15 thereon, forms the used conventional bead-welding technology of mild alloy layer 15 when being used to be described in moving electric arc generation unit 30.

In Comparative Examples 1, be similar to embodiment 1, the parent metal 40 that preparation is made by structural steel, this parent metal is partly simulated shaft bearing, and it has the internal diameter of 381mm, the external diameter of 481mm and 85 ° central angle.

Electric arc generation unit 30 is placed in a side end 40a place of parent metal 40, and applies predetermined voltage between electric arc generation unit 30 and parent metal 40, to generate electric arc 31.

Subsequently, electric arc generation unit 30 on the central axial direction in the interior week of parent metal 40 with the warble of amplitude and the 3Hz of 7mm, and flatly the side end 40a from parent metal 40 moves to the end side 40b of parent metal 40, with the speed of 40cm/min to 50cm/min mild alloy member 50 is inserted in the electric arc 31 simultaneously.So the mild alloy member is melted, and its width forms on the inner peripheral surface of parent metal 40 at the mild alloy layer 15 corresponding to the amplitude of electric arc generation unit 30 on the central axial direction.Here, as the mild alloy member, used white metal secondary (WJ2).

Subsequently, electric arc generation unit 30 moves distance corresponding to electric arc generation unit 30 amplitudes along the central axial direction in the interior week of parent metal 40, and further forms mild alloy layer 15 by identical method.

Subsequently, the multilayer of mild alloy layer 15, be that the second layer, the 3rd layer are stacked on the first layer of mild alloy layer 15 by identical method with the 4th layer, this mild alloy layer 15 is formed on the inner peripheral surface of parent metal 40, therefore forms the mild alloy layer 15 of the thickness with 12mm.

The parent metal 40 that adopts said method to produce mild alloy layer 15 is from it produced sample, and sample is carried out tension test and bond strength test.Notice that the shape of sample etc. are identical with sample in embodiment 1.Method of measurement in the test of tension test and bond strength, measuring condition etc. are also with identical in embodiment 1.In addition, adopt scanning electron microscope (SEM) to observe the cross section at the interface between mild alloy layer 15 and the parent metal 40,, thereby obtain its mean value with the thickness of measurement interfacial reaction layer 16.

The result of tension test and bond strength test is shown in Fig. 8 and Fig. 9.In addition, the average thickness of interfacial reaction layer 16 is 75 μ m.

(Comparative Examples 2)

In Comparative Examples 2, form the mild alloy layer by centrifugal casting.Here, will describe with reference to figure 22A to Figure 22 E.

In Comparative Examples 2, the parent metal 310 that preparation is made by structural steel, this parent metal 310 is partly simulated shaft bearing, and it has the internal diameter of 381mm and the external diameter of 481mm.

At first, as shown in Figure 22 A, the coating layer 311 that is formed by Ni (nickel) is formed on the inner peripheral surface of parent metal 310.

As shown in Figure 22 B, under this state, coating layer 311 is preheated by the heating equipment 312 that uses electric furnace, thereby diffuses to parent metal 310 sides, and integrated with parent metal 310.

Subsequently, for the bearing metal 313 of the mild alloy that formed by the white metal secondary (WJ2) under the molten state is poured into (referring to Figure 22 C) in the parent metal 310, and parent metal 310 is with the rotational speed rotation (referring to Figure 22 D) of 200rpm.Incidentally, at this moment, coating layer 311 is integrated and disappearance with the mild alloy of molten state.

Behind the casting complete of molten state bearing metal 313, cooling water 314 is injected on the outer circumferential face of parent metal 310, thus quenching parent metal 310, and the bearing metal 313 of molten state is solidified, therefore form mild alloy layer (referring to Figure 22 E).

Take a sample from the parent metal 310 that adopts said method to produce the mild alloy layer thereon, and sample is carried out tension test and bond strength test.Notice that the shape of sample etc. are identical with sample in embodiment 1.Method of measurement in the test of tension test and bond strength, measuring condition etc. are also with identical in embodiment 1.In addition, adopt scanning electron microscope (SEM) to observe the cross section at the interface between mild alloy layer (bearing metal 313) and the parent metal 310,, and obtain its mean value with the thickness of measurement interfacial reaction layer.

The result of tension test and bond strength test is shown in Fig. 8 and Fig. 9.In addition, do not observe interfacial reaction layer.

(summary of embodiment 1 and embodiment 2 and Comparative Examples 1 and Comparative Examples 2)

As shown in Fig. 8 and Fig. 9, compare with the mild alloy layer that adopts centrifugal casting to form in the Comparative Examples 2, the mild alloy layer that forms by bead-welding technology in embodiment 1, embodiment 2 and Comparative Examples 1 has higher tensile strength and the bond strength of Geng Gao, and has lower standard deviation.Therefore, find when using bead-welding technology that compare with using centrifugal casting, the mild alloy layer of acquisition has more excellent tensile strength and bond strength, the littler dispersion degree that has simultaneously on these intensity.In addition, in these examples that use bead-welding technology, the mild alloy layer that forms with do not keep the constant weld distance as in the Comparative Examples 1 is compared, formed mild alloy layer has higher tensile strength and bond strength in the welding distance constant by the maintenance of rotary substrate metal as among embodiment 1 and the embodiment 2, and has littler standard deviation.Especially, this tendency is fairly obvious in bond strength and standard deviation thereof.

Here, Figure 11 is the picture in the cross section at the interface between mild alloy layer 15 and the parent metal 40 among the observed embodiment 2 of employing scanning electron microscope (SEM).Figure 12 is the picture in the cross section at the interface between mild alloy layer 15 and the parent metal 40 in the observed Comparative Examples 1 of employing scanning electron microscope (SEM).The thickness (average out to 75 μ m) of the interfacial reaction layer 16 that the thickness (average out to 8 μ m) of finding the interfacial reaction layer 16 that forms on the interface between mild alloy layer 15 and parent metal 40 among the embodiment 2 forms on the interface between mild alloy layer 15 and the parent metal 40 in than Comparative Examples 1 is obviously thinner.

From the above, obviously, by keeping constant welding distance to make arc stability and result from the thickness of the interfacial reaction layer on the interface between parent metal and the mild alloy layer by control suitably, tensile strength and bond strength are enhanced, the dispersion degree on simultaneously can inhibition strength.

(embodiment 3)

In embodiment 3, the mild alloy layer that uses in embodiment 2 forms device 10 and is provided with cooled gas injection unit 60 and parent metal cooling unit 70, and as shown in Figure 5, and this mild alloy layer formation device 10 is used to form mild alloy layer 15.The formation method of the mild alloy layer 15 among other condition and the embodiment 2 is identical.

Here, as the cooled gas 61 of cooled gas injection unit 60, the flow with 10L/min (rise/minute) from the argon gas cartridge sprays argon gas.In addition, as parent metal cooling unit 70, used by parent metal 40 to be arranged on towards the nozzle of the position of electric arc generation unit 30, by this nozzle, temperature is that 10 ℃ water is injected on the outer circumferential face of parent metal 40.In addition, the average cooling rate of mild alloy layer 15 is about 44.1 ℃/second at this moment.In addition, be similar to the mild alloy layer 15 among the embodiment 1, the mild alloy layer 15 that forms on the inner peripheral surface 41 of parent metal 40 forms with four layers form, and has the thickness of 12mm.

Take a sample from the parent metal 40 that adopts said method to produce mild alloy layer 15 thereon, and sample is carried out tension test and bond strength test.Notice that the shape of sample etc. are identical with sample in embodiment 1.Method of measurement in the test of tension test and bond strength, measuring condition etc. also with embodiment 1 in identical.In addition, adopt scanning electron microscope (SEM) to observe the cross section at the interface between mild alloy layer 15 and the parent metal 40,, thereby obtain its mean value with the thickness of measurement interfacial reaction layer 16.In addition, adopt scanning electron microscope (SEM) to observe the cross section of mild alloy layer 15.

The result of tension test and bond strength test is shown in Figure 13.In addition, the thickness average out to 5 μ m of interfacial reaction layer 16.Figure 14 is the picture in the cross section of the observed mild alloy layer 15 of employing scanning electron microscope (SEM).

(embodiment 4)

In embodiment 4, removed in embodiment 3 mild alloy that uses and formed the parent metal cooling unit 70 of device 10, and this mild alloy that only has a cooled gas injection unit 60 forms device 10 and is used to form mild alloy layer 15.Identical among other condition and the embodiment 3 in the formation method of mild alloy layer 15.

Here, as the cooled gas 61 of cooled gas injection unit 60, the flow with 10L/min from the argon gas cartridge sprays argon gas.In addition, the average cooling rate of mild alloy layer 15 is about 39.4 ℃/second at this moment.In addition, be similar to the mild alloy layer 15 among the embodiment 1, the mild alloy layer 15 that forms on the inner peripheral surface 41 of parent metal 40 forms with four layers form, and has the thickness of 12mm.

Take a sample from the parent metal 40 that adopts said method to produce mild alloy layer 15 thereon, and sample is carried out tension test and bond strength test.Notice that the shape of sample etc. are identical with sample in embodiment 1.Method of measurement in the test of tension test and bond strength, measuring condition etc. are identical with in embodiment 1 also.In addition, adopt scanning electron microscope (SEM) to observe the cross section at the interface between mild alloy layer 15 and the parent metal 40,, thereby obtain its mean value with the thickness of measurement interfacial reaction layer 16.In addition, adopt scanning electron microscope (SEM) to observe the cross section of mild alloy layer 15.

The result of tension test and bond strength test is shown in Figure 13.In addition, the thickness average out to 6 μ m of interfacial reaction layer 16.Figure 15 is the picture in the cross section of the observed mild alloy layer 15 of employing scanning electron microscope (SEM).

(embodiment 5)

In embodiment 5, removed in embodiment 3 the mild alloy layer that uses and formed the cooled gas injection unit 60 of device 10, and this mild alloy layer that only has a parent metal cooling unit 70 forms device 10 and is used for forming mild alloy layer 15.Identical in the formation method of other condition and mild alloy layer 15 in embodiment 3.

Here, as parent metal cooling unit 70, used the water jacket of placing contiguously with lower half portion of the outer circumferential face of parent metal 40 71, as shown in FIG. 5.Temperature is that 10 ℃ cooling water is provided to water jacket.Here, Figure 16 shows the time dependent situation of mean value of the temperature variation of mild alloy layer 15.At this moment, the average cooling rate of mild alloy layer 15 is about 31.7 ℃/second.This average cooling rate is for being cooled to the speed of uniform temperature from the maximum temperature (450 ℃) of mild alloy layer 15, this uniform temperature is equal to or less than the solidifying of material that forms mild alloy layer 15 and begins temperature (300 ℃).In addition, be similar to the mild alloy layer 15 among the embodiment 1, the mild alloy layer 15 that forms on the inner peripheral surface 41 of parent metal 40 forms with four layers form, and has the thickness of 12mm.

The result of tension test and bond strength test is shown in Figure 13.In addition, the thickness average out to 8 μ m of interfacial reaction layer 16.Figure 17 is the picture in the cross section of the observed mild alloy layer 15 of employing scanning electron microscope (SEM).

(embodiment 2 is to embodiment 5 summary)

Figure 13 shows the result of tension test among the embodiment 2 and bond strength test, and the tension test of embodiment 3 to the embodiment 5 and the result of bond strength test, wherein embodiment 2 does not take any cooling unit, for example cooled gas injection unit 60 and parent metal cooling unit 70.

As shown in Figure 13, even find under identical built-up welding condition, compare with the mild alloy layer 15 among the embodiment 2, embodiment 3 all has more raising to the mild alloy layer 15 among the embodiment 5 aspect tensile strength and the bond strength, wherein parent metal 40 and mild alloy layer 15 all are not forced to cooling among the embodiment 2, and embodiment 3 parent metal 40 and mild alloy layer 15 to the embodiment 5 are forced to cooling.In addition, good more according to embodiment 3, embodiment 4 and embodiment's 5 this effect of order, force the degree of cooling high more, that is, the average cooling rate of mild alloy layer 15 is high more, and effect is good more.In addition, the average cooling rate among the embodiment 5 is about 31.7 ℃/second, and the average cooling rate among this embodiment 5 is minimum in embodiment 3, embodiment 4 and embodiment 5.

The reason that can expect about above-mentioned situation is, by cooling off mild alloy layer 15 from external forced, mild alloy layer 15 rapid solidification of molten state, thereby crystal grain thinning and separate out layer, in addition, being formed at the growth of the interfacial reaction layer 16 on the interface between parent metal 40 and the mild alloy layer 15 and the growth of Cu segregation layer is suppressed.Here, from to can clearly be seen that in the contrast that illustrated picture carries out Figure 14, Figure 15 and Figure 17, crystal grain and separate out layer according to the degree of forcing cooling by refinement, promptly, order according to embodiment 3, embodiment 4 and embodiment 5, the average cooling rate of mild alloy layer 15 is high more, and wherein these pictures are for adopting the cross section of the observed mild alloy layer 15 of scanning electron microscope (SEM).In addition, Figure 18 is the picture in the cross section of adopting the mild alloy layer 15 among the observed embodiment 2 of scanning electron microscope (SEM), wherein in embodiment 2 without any cooling unit, as cooled gas injection unit 60 and parent metal cooling unit 70.As shown in Figure 18, can clearly be seen that, compare to the mild alloy layer 15 among the embodiment 5 with embodiment 3, mild alloy layer 15 among the embodiment 2 has bigger crystal grain and the bigger layer of separating out, wherein in embodiment 2 without any cooling unit, as cooled gas injection unit 60 and parent metal cooling unit 70, has the cooling unit of cooled gas injection unit 60 and parent metal cooling unit 70 to the embodiment 5 in embodiment 3.Here, Figure 19 illustrates the time dependent situation of temperature variation mean value of mild alloy layer 15 among the embodiment 2.This moment, the average cooling rate of this mild alloy layer 15 was about 11.4 ℃/second.This average cooling rate is cooled to the speed of solidifying beginning temperature (300 ℃) of the material that forms mild alloy layer 15 for the maximum temperature (450 ℃) from mild alloy layer 15.

(interfacial reaction layer 16)

Be made of Fe, Sn and Sb and be formed at interfacial reaction layer 16 on the interface between parent metal 40 and the mild alloy layer 15 when too thin when main, its bond strength reduces.Simultaneously, when it was too thick, Cu segregation layer was formed on the interface between interfacial reaction layer 16 and the mild alloy layer 15, and its bond strength also can reduce.Therefore, preferably, on the interface between parent metal 40 and the mild alloy layer 15, be formed uniformly interfacial reaction layer 16 with predetermined thickness.

According to the measurement result of the interfacial reaction layer 16 of the foregoing description 1 to the embodiment 5, find that average thickness when interfacial reaction layer 16 is 5 μ m or when bigger, interfacial reaction layer 16 is formed on the interface between parent metal 40 and the mild alloy layer 15 almost evenly.On the other hand, when the average thickness of interfacial reaction layer 16 surpasses 20 μ m, tend to above-mentioned Cu segregation layer to occur.Therefore, by selecting the built-up welding condition, can form mild alloy layer 15 with excellent adhesion intensity so that the average thickness of interfacial reaction layer 16 is 5 μ m to 20 μ m.

(the Cu content in interfacial reaction layer 16)

Here, the Cu content in the mild alloy member 50 is changed, interfacial reaction layer 16 by with form as the identical method of the formation method of the interfacial reaction layer among the embodiment 2 16, and measure its tensile strength and bond strength.Here, as mild alloy member 50, white metal secondary (WJ2) uses as parent metal, and Cu content is changed simultaneously.

Produce parent metal 40 samplings of mild alloy layer 15 from it, and sample is carried out tension test and bond strength test with different Cu content.Notice that the shape of sample etc. are identical with sample in embodiment 1.Method of measurement in the test of tension test and bond strength, measuring condition etc. also with embodiment 1 in identical.Tension test and bond strength test result are shown in Figure 20.

Find that as shown in Figure 20 in the scope of these tests, along with the reduction of Cu content, the tensile strength of mild alloy layer 15 shows the trend that reduces gradually, bond strength shows the trend of increase simultaneously.The reason that can expect is, because the volume ratio of separating out layer that mainly is made of Cu in the mild alloy layer 15 is owing to the reduction of Cu content reduces, tensile strength reduces, simultaneously because of generation along with the interfacial reaction layer 16 on the interface that is formed between parent metal 40 and the mild alloy layer 15, the generation of Cu segregation layer is suppressed, and bond strength increases.

As shown in figure 20, when Cu content was 1wt% to 5wt%, as mild alloy layer 15, it had enough tensile strength and bond strength.In addition, from these results as can be seen, preferably, the Cu content that directly influences in the first layer of mild alloy layer 15 of bond strength is 1wt% to 5wt%.In order to improve tensile strength, preferably, the second layer and succeeding layer have the Cu content higher than first layer.Here, have following possibility, promptly when the second layer during by built-up welding, the part of first layer is melted once more, and the Cu content in the second layer reduces, and therefore more preferably, the Cu content of first layer is 3wt% to 5wt%.

Specifically described the present invention, but the present invention also only is not limited to these mode of executions, but can under the situation that does not break away from spirit of the present invention, changes in many ways by mode of execution.

Claims

1. a mild alloy layer forms device, and it forms the mild alloy layer by bead-welding technology on the inner peripheral surface of parent metal that is cambered surface, and described mild alloy layer is made of mild alloy and contacts with rotor slidably, and described device comprises:

The parent metal support unit, its central axis with the interior week of described parent metal is that spin axis supports described parent metal rotatably; And

The electric arc generation unit, it can be along the moving axially of described spin axis, and be fixed on the position that has intended distance with the inner peripheral surface of described parent metal, and described electric arc generation unit generates electric arc between himself and described parent metal,

Wherein when rotating described parent metal by described parent metal support unit and between the inner peripheral surface of described electric arc generation unit and described parent metal, keeping constant intended distance, the arc-melting that the mild alloy member quilt that is made of mild alloy is generated by described electric arc generation unit, thus the mild alloy layer on the inner peripheral surface of described parent metal, formed.

2. mild alloy layer according to claim 1 forms device, it is characterized in that, further comprises:

Spray the cooled gas injection unit of cooled gas to described mild alloy layer.

3. mild alloy layer according to claim 1 forms device, it is characterized in that, further comprises:

Cool off the parent metal cooling unit of the outer circumferential face of described parent metal.

4. one kind forms the mild alloy layer formation method of mild alloy layer by bead-welding technology on the inner peripheral surface of parent metal that is cambered surface, and described mild alloy layer is made of mild alloy and contacts with rotor slidably, and described method comprises:

Central axis with interior week of described parent metal is that spin axis supports described parent metal rotatably; And

At the described parent metal of rotation and when can between the inner peripheral surface of the axially movable electric arc generation unit of described spin axis and described parent metal, keep constant intended distance, form the mild alloy layer on the inner peripheral surface by the mild alloy member that constitutes by mild alloy at the arc-melting that generates between described electric arc generation unit and the described parent metal at described parent metal.

5. mild alloy layer formation method according to claim 4 is characterized in that,

In the forming process of described mild alloy layer, the welding current that is used to form the second mild alloy layer and follow-up mild alloy layer is less than the welding current that is used for forming the first mild alloy layer on the inner peripheral surface of described parent metal, and wherein said second mild alloy layer and follow-up mild alloy layer are formed on the described first mild alloy layer.

6. mild alloy layer formation method according to claim 4 is characterized in that,

Described mild alloy member is formed by alloy, described alloy contains copper (Cu) and antimony (Sb) and mainly is made of tin (Sn), and is used at the copper content that forms the first mild alloy layer on the inner peripheral surface of described parent metal less than the copper content that is used for forming the second mild alloy layer and follow-up mild alloy layer on the described first mild alloy layer.

7. mild alloy formation method according to claim 6 is characterized in that,

By weight, the copper content that is used to form the described first mild alloy layer is 1% to 5%.

8. mild alloy formation method according to claim 4 is characterized in that,

In the forming process of described mild alloy layer, spray cooled gas to described mild alloy layer.

9. mild alloy formation method according to claim 4 is characterized in that,

In the forming process of described mild alloy layer, the outer circumferential face of described parent metal is cooled.

10. mild alloy formation method according to claim 4 is characterized in that,

The average thickness of the interfacial reaction layer that forms on the interface between described parent metal and the described mild alloy layer is 5 μ m to 20 μ m.