JPH05131289A - Welding material for hard build-up - Google Patents

Abstract

PURPOSE:To enable the execution of hard build-up by using a plasma powder welding method which widens the temp. region between solid and liquid phases by an increased quantity of C, increases the deposition quantity of an intermetallic compd. Mo3Si even under shielding with an inert gas and is high in productivity. CONSTITUTION:This welding material for hard build-up consists of a Co-based alloy contg. 0.1 to 0.5wt.% C, 2.0 to 5.0wt.% Si, 0.01 to 1.0wt.% Mn, 7.0 to 15.0wt.% Cr, and 26 to 33wt.% Mo.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding material for hardfacing, and more particularly to a welding material for hardfacing of a Co-based alloy which is preferably used when performing arc overlay welding under an inert gas shield. It is a thing.

[0002]

2. Description of the Related Art As a means for improving the wear resistance of various parts, there is a case of overlay welding a welding material (a filler material) of a Co base alloy. For example, the valve faces of the intake and exhaust valves of diesel engines and gas engines have less soot and dust in the exhaust gas compared to gasoline engines, so metals directly rub against each other, resulting in poor fuel economy due to poor sealing performance. High wear resistance is required to prevent deterioration, and C (carbon): about 0.04% by weight, Si (silicon): about 2.0% by weight, Cr (chrome): about 8% by weight, Mo (Molybdenum): about 28% by weight, Co (cobalt): Triballoy 400 of Co-based alloy consisting of the balance
(Trademark of Deloro Stellite) and the like were overlay welded. As such a overlay welding method, an oxyacetylene gas welding method using a rod-shaped triballoy is generally used.

[0003]

However, in the above-mentioned oxyacetylene gas welding method, since the material to be welded (base material) is preheated and the operator manually overlay-welds and then gradually cools it, In addition to low productivity, there are problems in that welding work under a high temperature environment imposes a heavy burden on the operator and requires skill. Further, when austenitic heat-resistant stainless steel such as SUH36 is used as the material to be welded such as the exhaust valve, since it contains about 0.4% by weight of N (nitrogen), the Trivalloy 4 is used.
Since direct blow-up welding of 00 causes frequent blow holes, overlay welding of Stellite (trademark of Deloro Stellite) containing about 30% by weight of Cr that fixes N ₂ to the material to be welded is performed in advance. After that, it is necessary to cut the surface and overlay weld the triballoy, which further reduces the productivity.

On the other hand, it is conceivable to adopt a plasma powder welding method (PPW method) for performing arc overlay welding under a shield of an inert gas such as argon or helium, a TIG welding method and the like. According to such a welding method, there are advantages that high productivity can be obtained, automation can be performed, and the burden on the operator can be significantly reduced. However, because of local heating, the cooling rate is extremely fast and the molten metal Since the C content is low, the precipitation of intermetallic compound Mo ₃ Si having a hardness Hv of about 2000, which contributes to the improvement of wear resistance, is hardly observed.
Therefore, a sufficient effect of improving wear resistance cannot be obtained. That is, in the oxyacetylene gas welding method, C in the atmosphere penetrates into the molten metal and rises to about 0.2 to 0.8% by weight, which is the temperature range between the solid and liquid phases during solidification of the welding material. To facilitate precipitation of the intermetallic compound Mo ₃ Si, and in combination with the slow cooling rate, the intermetallic compound M
A large amount of o ₃ Si is deposited to improve wear resistance. Further, in the case of overlay welding Triballoy to SUH36 etc. containing N, there is no difference in the situation that the above-mentioned plasma powder welding method or TIG welding method requires overlay welding of stellite in advance. is there.

The present invention has been made in view of the above circumstances. An object of the present invention is to provide a Co-based material which has excellent wear resistance even in overlay welding by a plasma powder welding method or the like, which has high productivity. It is to provide an alloy welding material.

[0006]

In order to achieve the above object, the present invention is a welding material for hardfacing a Co-based alloy, which comprises 0.1 to 0.5% by weight of C and 2. 0-5.0 wt% Si, 0.01-1.0 wt% Mn (manganese), 7.0-15.0 wt% Cr, 26-33
It is characterized by containing Mo by weight.

[0007]

In the welding material for hardfacing according to the present invention as described above, since the content of C is larger than that of triballoy, welding for arc overlay welding under an inert gas shield such as plasma powder welding method is performed. Also in the method, the C content in the molten metal increases, the temperature range between the solid and liquid phases is expanded, and the intermetallic compound Mo ₃ Si easily precipitates during solidification. The compound Mo ₃ Si is well precipitated and wear resistance is improved. In this case, C <
At 0.1% by weight, the effect of expanding the temperature range between the solid and liquid phases is not sufficient, and the intermetallic compound Mo ₃ Si is insufficiently precipitated, while at C> 0.5% by weight, the precipitation of Cr carbide increases. Build-up cracking easily occurs.

Si is an alloy component of the intermetallic compound Mo ₃ Si, and is slightly larger than that of triballoy. Therefore, in combination with the increase of C, the intermetallic compound Mo ₃ Si is compounded. Increase the amount of precipitation. In this case, Si <
At 2.0% by weight, the effect of increasing the amount of precipitation of the intermetallic compound Mo ₃ Si is not sufficiently obtained, and at Si> 5.0% by weight, the amount of precipitation of the intermetallic compound Mo ₃ Si becomes excessively large, causing build-up cracking. It is generated or Si in the matrix is increased to deteriorate the PbO corrosion resistance.

Mn acts as a deoxidizer, but Mn <
If it is 0.01% by weight, a sufficient deoxidizing effect cannot be obtained, and Mn>
When it is 1.0% by weight, the flow of molten metal is poor and the shape is deteriorated.

Cr improves oxidation resistance and N ₂
However, if Cr <7.0% by weight, the oxidation resistance and the effect of fixing N ₂ cannot be sufficiently obtained, and Cr> 1
If it is 5.0% by weight, the precipitation of Cr carbide is increased and the build-up cracking is likely to occur. In this case, if Cr ≧ 10% by weight, a sufficient N ₂ fixing action can be obtained, and even if the member to be welded is SUH36 containing N such as the exhaust valve, stellite is not generated. The wear resistance can be enhanced by one-layer overlay welding without performing overlay welding in advance. However, if Cr <10% by weight, the N ₂ fixing effect is not always sufficient, and if the member to be welded is SUH36, blowholes are likely to occur. In that case, one or more of Ti (titanium), Nb (niobium), Zr (zircon), and Al (aluminum) for fixing N ₂ is 0.1 to 0.1 in total.
It is desirable to contain 5.0% by weight.
It is possible to suppress the generation of N ₂ blowholes while reducing the content of expensive Cr. If the total content of Ti, Nb, Zr and Al is less than 0.1% by weight, a sufficient N ₂ fixing action cannot be obtained, and if it is more than 5.0% by weight, the wear resistance is deteriorated and the viscosity is lowered. As a result, the molten metal does not sufficiently flow to the build-up portion, and the build-up failure is likely to occur. In addition, SUH3
The content of Cr is about 10% by weight or less or T
Even if the content of i, Nb, Zr, Al is 0,
Of course, good overlay welding can be performed.

Mo is an alloy component of the intermetallic compound Mo ₃ Si. When Mo <26% by weight, the intermetallic compound Mo ₃ Si is used.
Is not sufficiently precipitated, and the effect of improving wear resistance cannot be sufficiently obtained.
When o> 33% by weight, the melt flowability deteriorates due to the decrease in viscosity,
The molten metal does not sufficiently flow to the build-up portion, and the build-up failure is likely to occur.

If B (boron) is contained in an amount of 0.02% by weight or less, the viscosity and surface tension are reduced and the build-up failure such that the molten metal does not flow to the build-up portion is reduced. B> 0.0
When the content is 2% by weight, the flow of the molten metal becomes so good that the bead shape is deteriorated, and the hardness is increased so that the build-up crack is likely to occur.

Further, the welding material for hardfacing according to the present invention is preferably used for overlay welding of valve faces of exhaust valves and intake valves in diesel engines and gas engines which are required to have high wear resistance. However, it can be used not only for overlay welding of other parts that require wear resistance, but also because it has excellent high temperature corrosion resistance and heat resistance, such high temperature corrosion resistance and heat resistance are required. It can be used for overlay welding of parts as well.

When the above-mentioned welding material for hardfacing is used in the plasma powder welding method, a spherical material having a mesh size of about 80 to 350 mesh is preferably used. Such a powder welding material is manufactured by a well-known powder manufacturing method such as a gas atomization method. When used for TIG welding, a rod-shaped welding material having a diameter of, for example, about 2.0 to 3.2 mm is preferably used.

[0015]

As described above, according to the welding material for hardfacing of the present invention, the intermetallic compound Mo ₃ Si is sufficiently precipitated even in the welding method in which the arc overlay welding is performed under the inert gas shield. Since the wear resistance is improved, by adopting the plasma powder welding method or TIG welding method, etc., high productivity can be obtained and the overlay welding can be automated and the burden on the operator can be greatly reduced. Of.

For a welded member such as SUH36 containing N, the content of Cr having an N ₂ fixing action may be increased, or one or more of Ti, Nb, Zr and Al may be used. By adding N, the generation of blow holes due to N ₂ can be suppressed, and the wear resistance can be improved by the overlay welding of one layer without overlay welding of stellite or the like in advance.

Further, when B is contained in an amount of 0.02% by weight or less, the viscosity and the surface tension are reduced, the build-up failure such that the molten metal does not flow to the build-up portion is reduced, and the yield is improved.

[0018]

EXAMPLES Examples of the present invention will be specifically described below.

FIG. 1 shows an example of a plasma powder overlay welding apparatus capable of suitably performing overlay welding using the welding material for hardfacing according to the present invention, and 10 is a plasma arc vertically arranged. It is the tip of a torch (hereinafter referred to simply as the torch). The torch 10 is provided with a tungsten electrode 12 at the center thereof, and a torch inner cylinder 14 and a torch outer cylinder 16 are coaxially arranged outside the electrode 12 with a predetermined distance. Between the electrode 12 and the torch inner cylinder 14, and between the torch inner cylinder 14 and the torch outer cylinder 16
Between the and, respectively, annular passages 18 and 20 are formed. The passage 18 is connected to a plasma gas supply device 24 via a pipe 22 so that plasma gas such as argon gas is supplied. Then, the plasma gas supplied into the passage 18 is ejected downward from the nozzle 30 provided at the tip of the torch inner cylinder 14. The passage 20 is connected to a carrier gas supply device 34 through a pipe 32, and a powder welding material for build-up welding is supplied from a powder supply device 36 connected to an intermediate portion of the pipe 32. A carrier gas containing a predetermined amount of powder welding material is supplied to 20, and jetted downward from a nozzle 38 provided at the tip of the torch outer cylinder 16.
An inert gas such as argon gas or helium gas is used as the carrier gas.

The torch inner cylinder 14 and the torch outer cylinder 16
The nozzles 30 and 38 of the
And 42 are formed to be cooled.
Further, a shield gas consisting of an inert gas such as argon gas or helium gas is supplied from the shield gas supply device 44 to the tip portion of the torch outer cylinder 16 through a pipe 46. Is blown out in a substantially cylindrical shape in the axial direction of the torch 10, so that the overlay welding portion is shielded from the atmosphere.

Below the torch 10 constructed as described above, a valve 48 of a diesel engine, a gas engine or the like to be subjected to overlay welding is arranged. The valve 48 is made of martensitic stainless steel such as SUH3 or austenitic stainless steel such as SUH36, and is provided with a shaft portion 50 and an umbrella portion 52, and overlay welding is performed on the umbrella portion 52. An annular recess 54 for applying is formed. Such a valve 48 is
The mounting shaft 56 is provided so as to be inclined by an angle θ with respect to the vertical direction, and is mounted via a cooling backing 58 with its axis A aligned with the axis of the mounting shaft 56. It is rotationally driven around the axis A at a predetermined speed together with the shaft 56. The recessed portion 5 formed in the umbrella portion 52 of the valve 48 when attached to the attachment shaft 56.
A portion of the valve 4 located on the upper side around the axis is positioned directly below the nozzle 38 of the torch 10, and the valve 48 is rotated around the axis A, so that the annular recess 54 has the entire circumference. The nozzles 38 are sequentially positioned immediately below the nozzle 38.

On the other hand, a predetermined pilot current is supplied from a pilot power source 60 between the electrode 12 of the torch 10 and the torch inner cylinder 14, and a backing 58 to which the electrode 12 and the valve 48 are attached. A predetermined welding current is supplied from the main power source 62 between and. In addition, the electrode 12 and the torch inner cylinder 14
A high frequency oscillator 64 for ignition is provided in parallel with the pilot power supply 60.

Then, a pilot current is supplied from the pilot power source 60, and the tip of the electrode 12 and the torch inner cylinder 14 are supplied.
When a plasma arc is supplied from the plasma gas supply device 24 into the annular passage 18 while a pilot arc is generated between the plasma arc and the nozzle 30, the plasma arc is formed at the tip of the electrode 12. Next, the electrode 12 and the backing 5
8, a welding current is supplied from the main power source 62 to the plasma arc formed at the tip of the electrode 12 by the bulb 4
8, the carrier gas including the powder welding material is supplied into the passage 20 from the carrier gas supply device 34 and the powder supply device 36. The powder welding material supplied into the passage 20 is jetted from the nozzle 38, melted by the plasma arc, and welded to the recess 54 of the valve 48 by overlay welding. At this time, the shield gas is blown out from the tip of the torch 10 so that the melted powder welding material and the recess 54 are not affected by oxygen in the air. In this state, the valve 48 is moved to its axis A
When it is rotated around, the portion of the recess 54 to be overlay welded moves, and overlay welding is sequentially performed on the entire circumference of the annular recess 54. The broken line shown in the concave portion 54 is a state in which overlay welding is performed.

Here, as the above-mentioned powder welding material, the welding material for hardfacing of Co-based alloy shown in Table 1 is used,
The results obtained by performing overlay welding on the valve 48 made of SUH3 or SUH36 and examining the presence or absence of cracks and blowholes in the overlay, the Ogoshi type wear amount (wear resistance), and the occurrence rate of overlay defects are shown in Table 2. Shown in. The welding materials shown in Table 1 are all 40 μm in diameter by a gas atomization method using a metal melt having the chemical composition shown in the table.
A spherical powder having a diameter of about 150 μm was prepared. For No. 11 of Comparative Example, a rod having a diameter of 4.0 mm prepared by a casting method was also prepared. In the comparative example, a numerical value with a dotted point indicates that it deviates from the component range of the present invention. Valve 4 as a member to be welded
In No. 8, the diameter of the umbrella portion 52 is 40 mm and the width dimension of the concave portion 54 is 4 mm. The presence or absence of "cracking in the overlay" in Table 2 is based on a color check, and the presence or absence of "blowing hole in the overlay" is based on X-rays, and "Ogoshi's wear amount (wear resistance)" is Measured using SUJ2 as the mating material,
The “defective rate (%)” is the rate of occurrence of defective products due to insufficient build-up when 1000 pieces of build-up welding are performed. The unit of "Ogoshi's wear amount" is mm ³ / (kgf · mm). The overlay welding is performed by an inert gas shield plasma powder welding method using the plasma powder overlay welding device and the like except for the No. 11 welding material, the current is 110 A, and the flow rate of the plasma gas is 10 ^{−. 3} m ³ / min, build-up speed is 50 cm
/ Min. Overlay welding of No. 11 welding material is SU
For H3 valves, direct overlay welding using the oxyacetylene gas welding method, for SUH36 valves,
Stellite # 12 was overlay welded to the recess 54 in advance by the oxygen acetylene gas welding method, and then the surface was cut and processed by the oxygen acetylene gas / plasma powder welding method to obtain No11.
The welding material of was welded by overlay welding.

[0025]

[Table 1]

[0026]

[Table 2]

As is clear from Table 2 above, among the welding materials No. 1 to No. 10 according to the present invention, the welding material No. 2 is SU.
With the exception of the case of overlay welding to a valve made of H36, a cured overlay having excellent wear resistance was obtained at a low defect rate without causing defects such as cracks and blowholes. When the No. 2 welding material is overlay welded to a SUH36 valve, blowholes due to N ₂ are observed, but S
There is no problem in overlay welding to a UH3 valve.
No3 welding material containing 14.1 wt% Cr, Ti, N
For No4, No5, No6, No7, No9, and No10 welding materials containing a small amount of one or more of b, Zr, and Al, hard overlay welding is also performed well on SUH36 valves. be able to. In addition, according to the No. 8 to No. 10 welding materials containing a small amount of B, insufficient build-up due to poor flow of molten metal is prevented, the defective rate is significantly reduced, and a high yield is obtained.

On the other hand, in the comparative example, when the No. 11 welding material was overlay welded to the valve made of SUH3 using the oxyacetylene gas welding method, and the plasma powder welding method was used after the overlay welding of the stellite to the valve made of SUH36 in advance. Using No
When the welding material of No. 11 was welded by overlay welding, good hardfacing was obtained, but other than that, not only sufficient wear resistance could not be obtained, but also cracking or SU
There was a problem that blowholes frequently occurred for H36 valves. In addition, those having cracks in the built-up portion were excluded from the measurement of wear resistance and defective rate.

The above description is merely one specific example of the present invention, and the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating an example of a plasma powder overlay welding apparatus that can preferably perform overlay welding using the hardfacing welding material of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yuji Takano 2958 Ishikawa, Fujisawa-shi, Kanagawa Fuji Valve Co., Ltd. Fujisawa Factory (72) Masahito Hirose 2958 Ishikawa, Fujisawa, Kanagawa Fuji Valve Co., Ltd. Fujisawa Factory

Claims (3)

[Claims] 1. A Co-based alloy comprising 0.1 to 0.5% by weight of C, 2.0 to 5.0% by weight of Si, and 0.01 to 0.5% by weight.
1.0 wt% Mn and 7.0-15.0 wt% Cr
And 26 to 33% by weight of Mo, a welding material for hardfacing. 2. The welding material for hardfacing according to claim 1, which contains one or more of Ti, Nb, Zr, and Al in a total amount of 0.1 to 5.0% by weight. 3. The welding material for hardfacing according to claim 1, which contains 0.02% by weight or less of B.