JPH069758B2 - Overlay arc welding wire and material reforming method using the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a build-up arc welding wire for modifying a metallic material by build-up arc welding, and a material modifying method performed using the wire. Is.

[Prior Art] Recently, there has been a demand for a technology of partially modifying various materials to improve their functions.

As the background, for example, in the field of automobile parts,
Along with the increase in output of the engine, a cylinder head manufactured from cast iron or the like has a problem that a mechanical load increases at the same time as a thermal load due to a temperature rise.

That is, as shown in FIG. 10, due to this increase in load, the lower surface 2 of the cylinder head 1, particularly between the exhaust port 3 and the intake port 4 which is a portion relatively thinner than other portions (intervalve portion), and Thermal cracking occurs in the portion 6 between these and the fuel injection nozzle hole (or the pre-combustion chamber hole) 5.

Further, as shown in FIG. 11, even in the piston 7, a crack is likely to occur around the combustion chamber 8 having a large load (indicated by diagonal lines in the drawing), and this is a portion to be strengthened here.

As a local strengthening method (surface modification method) that has been conventionally adopted as a countermeasure against this, there is the following technique.

Alloying: Add heat-resistant components (Cr, Mo, Cu, Ni, etc.) in appropriate amounts to improve heat-resistant strength.

Cast-in: Cast-in a steel material and a heat-resistant metal material in the area where the heat cracks occur.

Nitriding treatment: After heating, nitriding treatment is performed in gas or liquid to form a nitriding layer on the surface.

If the part is an aluminum alloy casting, in addition to, there were the following technologies.

Improvement treatment: Add appropriate amount of strontium or titanium to refine the precipitated crystal grains and increase the tensile strength.
Improves elongation characteristics and heat resistance.

Hard alumite treatment; Hard alumite treatment coating 100
The heat resistance is improved by forming it to about μm.

Remelting process: The aluminum base material is melted and rapidly cooled and solidified by a high-density energy source such as a laser, an electron beam, and TIG, and the crystal grains are miniaturized to improve heat resistance.

Alloy remelting process; heat resistant components (Ni, C
u, Cr, Mo, etc.) is added to refine the crystal grains in the remelted portion and simultaneously alloy.

[Problems to be Solved by the Invention] However, these conventional techniques have the following problems.

Alloying ... In addition to high cost, castability deteriorates due to the addition of alloys, and casting defects such as "drawing cavities" cause productivity and yield to deteriorate. Further, due to the deterioration of the castability, the amount of micro-shrinkage that greatly affects the heat resistance increases, and alloying may rather deteriorate the heat resistance.

Cast-in ... In order to ensure cast-in performance, it is necessary to prevent oxidation, thoroughly control the temperature of the cast-in, and perform a destructive inspection after casting, resulting in a significant increase in man-hours.

Nitriding process ... At the same time as high cost, the whole is exposed to a high temperature of 560 to 580 ° C, so deformation or crevice inside cast iron parts becomes a problem. Further, in order to perform nitriding more completely, it is necessary to remove graphite in the cast iron material.

Further, the conventional technique in the case of aluminum casting has the following problems.

Improvement treatment: A simple improvement method, but the effect is small.

Hard alumite treatment: The effect of improving heat resistance is greater than the above, but in order to treat only the part where cracks occur, alumite removal treatment by masking other parts is required, which is a time-consuming and expensive process.

Remelting treatment: The treatment method is simple and has a large effect of improving the heat resistance, but it is insufficient for the currently required heat resistance improvement target.

Alloy remelting treatment: The heat resistance is more effectively improved as a potential, but it is difficult to form a sound (no defect, no crack after remelting alloying) remelting alloyed layer. In order to prevent defects or cracks after processing, it is necessary to suppress the concentration of the additional element to 10 to 2% or less, and it is not possible to expect significant improvement in heat resistance.

As another technique, a method of spraying heat-resistant ceramics or heat-resistant material onto the relevant part (the lower surface of the cylinder head) has been proposed, but it has not been put to practical use because of the problem of early delamination of the sprayed layer. Not in.

On the other hand, particularly in cast iron parts, as a new technique, in order to avoid the problems of the above-mentioned conventional techniques, a heat-resistant metal (Co , Ni, Mo, etc.) have been considered.

However, this method has a problem that brittle cementite (Fe ₃ F) is deposited at the boundary between the refractory metal and the base material (cast iron) in the manufacturing process. This cementite is not only fragile but also causes a significant decrease in machinability. Further, this method also causes a problem that the deposited refractory metal causes cracks in the manufacturing process.

Also in the case of aluminum alloy castings, a method of depositing a heat-resistant element has been considered in order to avoid the problems of the above-mentioned prior arts.

However, this method has the problem that it is impossible to increase the concentration of the added heat-resistant element because of the problems of welding and cracking after welding, as in the case of remelting the alloy, and it is not possible to expect a significant improvement in heat resistance. .

The present invention has been made to solve the above problems. That is, it is an object of the present invention to secure sufficient strength and prevent the occurrence of cracks due to heat or mechanical load when locally strengthening a material. For example, when improving cast iron parts, in order to provide a modification method and a wire used therefor, which does not cause brittleness due to cementite precipitation, deterioration of machinability, and cracks, and aluminum alloy castings. The present invention was devised to provide a reforming method that can significantly improve the heat resistance of the material and that does not cause cracks, and a wire used for the method.

[Means and Actions for Solving the Problem] The invention of claim 1 is a wire used for build-up arc welding, wherein the surface of core particles is coated with coating particles having a diameter smaller than the core particles. According to the object to be modified and the conditions, the wire is made of metal as the coating particle or the sheath material, or the core particle is made of a heat-resistant material. And the coated particles and the sheath material can be made of metal. Further, it is preferable that the capsule particles are produced by a high-speed air flow impact method.

A fifth aspect of the present invention is a method for modifying a material using a wire filled with capsule particles, wherein capsule particles having the surface of the core particles coated with coating particles having a diameter smaller than the core particles are contained in a sheath material. It is characterized in that build-up arc welding is performed on the material to be modified by using the filled wire.

The wire used in the material modification method of the present invention is such that the coated particles and the sheath material are made of a material having a good compatibility with the material to be modified, or a material of the same quality as the material to be modified. Can be configured as. When the target to be modified is a cast iron part,
It is desirable to perform build-up arc welding using a wire whose core particles are a heat-resistant material, which is a coated particle and a sheathing metal, and when the object to be modified is an aluminum alloy casting part. It is preferable that the core particles are made of a heat-resistant material and the coated particles and the sheath material are made of aluminum to perform the build-up arc welding.

The capsule particles referred to in these inventions are powders to be core particles, for example, metal powders, and coated particles having a diameter smaller than this, for example, core particles are particles coated with foreign metal powders. The coated particles preferably have a diameter of about 1/10 of the core particles.

The capsule particles are in the form of a mixture of a powder serving as a core particle and a powder serving as a coated particle as a single particle. Usually, even if two kinds of powders are mixed, one of the powders is unevenly distributed, and it is very difficult to mix them uniformly. However, the capsule particles are already 2
Since the powders of different types are mixed, when they are aggregated, they become a mixed powder in a very uniform state.

Therefore, by filling the sheath particles with the capsule particles and performing arc welding for overlaying, it is possible to perform good arc welding without temporal fluctuations in the molten state and melting conditions of the wire. In the structure of the built-up portion, both particles are evenly dispersed and arranged, so that sufficient strength and tear resistance can be secured.

In addition, the coated particles and core particles can be properly selected in accordance with the material to be modified and the sheath material, so that a sound reinforcing layer free from welding defects can be obtained.

EXAMPLES Examples of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 to 8 show a first embodiment of a wire for overlay welding and a material reforming method using the same according to the present invention. It is a method of overlay welding on a cast iron part by using a wire formed by filling a metal sheath material with a plurality of capsule particles coated with metal particles having a smaller diameter than this.

First, a method for manufacturing a wire for build-up arc welding and its configuration will be described.

As shown in FIG. 1, particles 11 of Co, which is a heat-resistant material,
In addition, Cu, which is a metal with a particle size of about 1/10 of that, is particle 1
2 is attached. This adhesion force is due to the known van der Waals force. In this way Cu particles 12
An appropriate impact force is applied to the Co particles 11 surrounded by. Due to this impact action, the Cu particles 12 firmly adhere to the Co particles 11 that are the mother particles, and as shown in FIG. 2, the capsule particles 1 composed of the core particles 13 of Co and the coated particles 14 of Cu.
5 are manufactured. A large number of the capsule particles 15 are aggregated to form a composite powder 16 as shown in FIG.

FIG. 4 shows an example of a system for producing the composite powder 16 of the capsule particles 15.

This system is for producing capsule particles by a dry method called a high-speed air impact method, and an electrostatic treatment device 17 for adhering smaller particles to the particles.
A supply device 18 for appropriately transferring and sending out the adhered particles, a rolling device (hybridizer) 19 for applying an impact force to the particles, and a powder collector for containing the produced composite powder 16. And 20. Further, a control operation device 21 for appropriately controlling the operations of these devices 17, 18 and 19 is provided.

As shown in FIG. 5, in the rolling device 19, a rotor 24 having a blade 23 on a stator 22 is rotatably provided, and particles examined from an input port 25 are indicated by broken line arrows in the figure. As described above, it is blown off from the shaft center by a centrifugal force, receives an impact force in this process, and is repeatedly thrown into the high-speed airflow through the circulation circuit 26. When the discharge valve 27 is opened, it is discharged from the discharge port 28.

Co particles 11 and Cu particles 12 attached to the Co particles 11 are put into the rolling device 19, and an impact is applied in a high-speed air flow for 1 to 10 minutes. At this time, the rotation speed of the rotor 24 is 8,000 to 1
Set to 6,000 rpm. As a result, the firmly adhered capsule particles 15 (composite powder 16) are obtained.

In addition, as a method of molding the capsule particles 15,
In addition to the above methods (high-speed airflow casting impact method), known sputtering methods, wet methods, displacement plating methods, electroless plating methods, CV
D method, vacuum deposition method, alkyloside method, eutectoid method, eutectoid-reduction method, shervitt method and the like can be used.

Next, as shown in FIG. 6, the capsule particles 15 are granulated with zinc stearate or the like in a pipe 29 which is a sheath material manufactured by a Cu wrought material, and then the hollow portion is filled.

Then, this pipe 29 is thinly drawn to form a welding wire 30 having a diameter of 0.8 to 1.6 mm as shown in FIG. The welding wire 30 is a build-up arc welding wire that is a feature of the present invention. The welding wire 30 is manufactured by a known flux-cored wire.
You can do the same as with.

This welding wire 30 is set in a welding device 31 for performing MIG welding as shown in FIG.

The welding device 31 includes a nozzle 32 for blowing out the shield gas G and a wire feeding device 33 for sequentially feeding the welding wire 30, and performs arc welding using the welding wire 30 as a consumable electrode.

Then, the welding device 31 in which the welding wire 30 is set is moved along the surface of the portion 6 of the cylinder head 1 that is a cast iron part to be modified, and the build-up arc welding is performed using the welding wire 30 as a filler material. That is, the molten metal layer 34 to which Co is added is formed at the place where the cylinder head 1 needs to be strengthened.

After the build-up arc welding is completed, a predetermined cylinder header 1 is finished by machining.

Thus, the Co-coated particles 1 with Co as the core particles 13
Since the Cu-made pipe 29 is filled with the capsule particles 15 surrounded by 4, the welding wire 30 is formed, and the welding wire 30 is used as a filler material to be deposited on the corresponding portion 6 of the cast iron part. With the above characteristics, the heat resistance strength of the local portion of the cylinder head can be improved, and the precipitation of cementite and the occurrence of cracks can be prevented.

That is, even if the welding conditions are such that Co melts,
Is surrounded by Cu and therefore does not come into contact with cast iron. Therefore, cementite is hardly deposited in the alloyed molten metal layer 34, and the amount thereof is extremely limited. However, there is no fear that the build-up arc welding will weaken and reduce machinability.

Further, in the molten metal layer 34, Co has a form in which it is uniformly dispersed and arranged as particles in a Cu matrix that is highly compatible with cast iron, so the cause of cracking when plating with only refractory metal is mitigated. As a result, a sound reinforcing layer without welding defects is obtained.

Since the welding wire 30 is formed by filling the plurality of capsule particles 15, the electric resistance during arc welding becomes uniform. This is because it is difficult to mix them uniformly when producing a mixture of heat resistant material particles and Cu particles. Therefore, due to the non-uniformity of the mixed particles, the electric resistance varies in the length direction of the wire, which makes it very difficult to perform stable weld overlay. The present invention obviates such difficulties.

The present inventors conducted a build-up welding test on cast iron (JIS FC 25) based on the above-mentioned Examples in order to confirm the effects of this material modification method.

The test conditions are as follows.

Welding wire: Outer diameter 1.5 mm, wall thickness of pure copper wrought material 0.15 mm Capsule particles: Cu / Co, Cu / Mo, Cu / Cr (weight ratio 3 for each
0/70%) Welding conditions: 160A, 23kV As a result, in the case of pure Mo, Co-based (Stellite # 12), Cr-based (SUS309) plain welding, remarkable cracks occurred in the molten metal, whereas When the melting wire 30 of the invention was used, cracks did not occur, and welding could be performed without welding defects. That is, a sound molten metal layer could be formed, demonstrating the usefulness of the present invention.

As the capsule particles, various combinations other than the combination of Co, Mo, and Cr are conceivable, and as the heat-resistant material, other heat-resistant metal or Al is used.
Ceramic particles such as ₂ O ₃ , SiC, Si ₃ N ₄ and CuO can also be used.

Further, the shape (cross section) of the welding wire is not limited to that shown in FIG. 7 and may be any shape as long as it can fill the capsule particles 15. For example, it may be selected from various shapes used for the flux-cored wire.

Furthermore, although MIG welding is shown as a welding method for overlaying, another welding method (TIG welding or the like) may be used as long as it is an arc welding method using a welding wire.

Next, a second embodiment of the present invention will be described.

In this example, a core particle of a heat-resistant material, a wire formed by filling a plurality of capsule particles coated with aluminum particles of a smaller diameter in an aluminum sheath material, aluminum alloy casting such as a cylinder head It is the one that build-up arc welding is applied to parts.

The wire is manufactured in the same manner as in the first embodiment described above.
That is, aluminum particles having a particle size of about 1/10 of that of the heat-resistant material, Mo, are electrostatically adhered to the particles, and the particles are put into a high-speed air stream. To bite into. As a result, as shown in FIG. 9, capsule particles 43 composed of Mo core particles 41 and aluminum coated particles 42 are manufactured.

Next, a pipe made of an wrought aluminum material is filled with capsule particles 43, and this pipe is drawn to obtain a diameter
Form a welding wire of 0.8 to 1.6 mm.

Then, this welding wire is set in the welding device for performing the above-mentioned MIG welding, and this welding device is moved along the surface of the corresponding portion of the aluminum alloy cylinder head to build up the weld wire with the welding wire as an additive. Weld. That is, a molten metal layer to which Mo is added is formed at a place where the cylinder head needs to be strengthened.

Thus, Mo is the core particle 41 and aluminum is the coated particle 4
The capsule particles 43 of No. 2 were filled in an aluminum pipe to form a welding wire, and the welding wire was used as a filler material to be built up at a corresponding portion. A great improvement in heat resistance can be achieved, and cracks can be prevented from occurring during and after welding.

That is, in the molten metal layer, Mo has a form in which it is uniformly dispersed and arranged as particles in a matrix of aluminum of the same quality as the aluminum alloy casting, so the cause of cracking when plating with only refractory metal is removed. As a result, a sound reinforcement layer without welding defects is obtained.

Therefore, as compared with the conventional synthetic remelting treatment, the limitation of the concentration of the added heat-resistant material is significantly relaxed, and the capsule particles 43
By changing the diameter (ratio to the aluminum particle diameter) of the heat-resistant material particles in (1), the temperature can be set to an arbitrary temperature.

Besides, as in the first embodiment, there is an effect that the electric resistance during arc welding can be made uniform.

The inventors of the present invention have confirmed that the operation and effect of the second embodiment are based on the above-mentioned embodiment, based on the above-mentioned embodiment, and cast aluminum alloy (JIS AC2B)
A build-up welding test was performed on the.

The test conditions are as follows.

Welding wire: Outer diameter 1.2 mm, wall thickness of pure aluminum wrought material 0.15 mm Capsule particles: Al / Co, Al / Mo, Al / Cr (each weight ratio 3
0/70%) Welding condition: 170A, 25kV As a result, in the case of pure Mo, Co-based (Stellite # 12), Cr-based (SUS309) plain welding, remarkable cracks were generated in the molten metal. When the molten wire of the invention was used, cracks did not occur, and welding could be performed without welding defects. That is, a sound molten metal layer could be formed, demonstrating the usefulness of the present invention.

As the capsule particles to be used, as in the first embodiment, a heat-resistant metal, Al ₂ O ₃ , or
Ceramic particles such as SiC, Si ₃ N ₄ and CuO can be used as the core particles.

[Effects of the Invention] In summary, according to the present invention, the following excellent effects are exhibited.

(1) According to the wire according to any one of claims 1 to 3, when arc welding is performed, the core particles are uniformly dissolved in the material to be modified and segregation of one component does not occur, and the metal is It is possible to obtain a buildup reinforcing layer that is structurally dense. In particular, according to the wire of claim 2 or 3, when used as a filler metal for arc welding, electric resistance becomes uniform and stable welding overlay can be performed.

(2) According to the invention of claim 4, stable quality capsule particles can be obtained at a relatively low cost.

(3) According to the material reforming method of claims 5 to 7, it becomes possible to carry out the buildup by arc welding so that the core particles are uniformly dissolved in the material to be reformed. It is possible to obtain a reinforcing layer having high compactness and excellent heat resistance and crack resistance. In particular, according to the material reforming method of the sixth or seventh aspect, the material to be reformed, that is, the base material, is well compatible, and the occurrence of cracks due to welding can be more reliably prevented.

(4) According to the material modification method of claim 8, local strengthening is achieved in a cast iron part by adding a heat resistant material, and precipitation of cementite in the manufacturing process is suppressed to weaken and reduce machinability. Can be prevented and the occurrence of cracks can be prevented.

(5) According to the material modification method of claim 9, in the aluminum casting alloy part, a large improvement in heat resistance strength can be achieved by the addition of the heat resistant material, and cracks in the manufacturing process can be prevented.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a manufacturing process of capsule particles for explaining a first embodiment of a wire for overlay welding and a material modifying method using the wire according to the present invention, and FIG. Is a cross-sectional view showing the manufactured capsule particles, FIG. 3 is a cross-sectional view showing a composite powder which is an aggregate of the capsule particles, and FIG. 4 is a configuration diagram showing a system for manufacturing the capsule particles. FIG. 5 is a cross-sectional view showing a rolling device in the system, FIG. 6 is a perspective view showing a process of filling the capsule particles of FIG. 3 into the sheath material, and FIG. 7 is manufactured by the sheath material. Fig. 8 is a perspective view showing a wire, Fig. 8 is a side view of a welding apparatus for explaining build-up welding, and Fig. 9 is a sectional view of capsule particles for explaining a second embodiment of the present invention. FIG. 10 is a bottom view of a cylinder head for explaining the problems of the prior art, FIG. 11 is a perspective view of a piston for explaining problems of the prior art. In the figure, 13 is a core particle, 14 is a coated particle, 15 is a capsule particle, 29 is a pipe of Cu wrought material as a sheath material, and 30 is a welding wire which is a wire for build-up arc welding.

Claims (9)

[Claims] 1. A wire for build-up arc welding, characterized in that a sheath material is filled with capsule particles in which coating particles having a diameter smaller than that of the core particles are coated on the surface of the core particles. 2. The wire for build-up arc welding according to claim 1, wherein the coated particles and the sheath material are metals. 3. The wire for build-up arc welding according to claim 1, wherein the core particles are a heat resistant material, and the coated particles and the sheath material are metals. 4. The wire for build-up arc welding according to claim 1, wherein the capsule particles are produced by a high-speed air current impact method. 5. A wire to be modified by using a wire obtained by filling capsule particles in which coating particles having a diameter smaller than that of the core particles are coated in a sheath material, to build up the material to be modified. A material reforming method characterized by performing arc welding. 6. The material modification according to claim 5, wherein the coated particles and the sheath material are subjected to build-up arc welding by using a wire made of a material having a good compatibility with a material to be modified. Quality method. 7. The material reforming method according to claim 5, wherein the coated particles and the sheath material are subjected to build-up arc welding using a wire made of the same material as the material to be reformed. . 8. The material modification according to claim 5, wherein the core particles are a heat-resistant material, and the overlaying arc welding is performed on the cast iron part using a wire in which the coated particles and the sheath material are metal. Quality method. 9. The build-up arc welding method according to claim 5, wherein the core particles are made of a heat-resistant material, and the coated particles and the sheath material are made of aluminum to perform build-up arc welding on an aluminum alloy casting part. Material modification method.