JPH064200B2 - Overlaying method on metal base material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for overlaying a metal base material by forming a build-up layer on the metal base material using a metal powder.

[Conventional technology]

Conventionally, as shown in FIG. 1, this type of overlaying method has been such that a metal powder b is supplied onto a metal base material a, and this is rapidly melted and solidified by a rotating laser beam c.

[Problems to be Solved by the Invention]

When overlaying is carried out by the above-mentioned conventional method, boilers are generated in the molten pool due to the oxidation of C, Cr, etc. in the components of the metal base material a and the metal powder b, and there are problems such as the generation of blowholes and the inclusion of slag. It was happening. Further, even if some blowholes are allowed, there is a problem that the surface irregularities are large, this finishing process requires man-hours, and the yield is low.

The reason for this is that when air is entrained in the supply of metal powder, oxygen in the air and C and Cr in the components of the metal base material a and the metal powder b are included.
Etc. due to a chemical reaction. This is exactly the same when the powder is previously molded using a binder.

DISCLOSURE OF THE INVENTION The present invention aims to solve the above-mentioned problems, and furthermore, it is possible to form an extremely uniform and high-quality build-up layer while solving the above-mentioned problems, and a build-up method on a metal base material. Is provided.

[Means for Solving the Problems] In order to achieve the above object, a method of overlaying a metal base material according to the present invention is a method of supplying a laser beam and a overlaying metal powder in an inert gas atmosphere. The pipe is made coaxial and supplied onto the metal base material.

[Action]

The hardfacing metal powder supplied on the metal base material is irradiated with a laser beam in an atmosphere of an inert gas to be generated in a molten pool,
The metal powder is fused on the surface of the metal base material.

At this time, the build-up metal powder is fused to the surface of the metal base material in an inert gas atmosphere, and the oxidation reaction of the metal powder in the molten pool and the components such as C and Cr in the surface layer of the metal base material is prevented. It can be prevented. In addition, the fact that the inert gas atmosphere can be maintained over the metal base material and the metal powder located on the metal base material means that the gas that is involved in the reaction such as air existing in each powder gap of the metal powder is caused by the inert gas. As a result, it contributes to the prevention of the above-mentioned oxidation reaction.

〔Example〕

Next, specific examples of the method for overlaying a metal base material according to the present invention will be described with reference to the drawings.

In FIG. 2, reference numeral 1 denotes a metal base material placed on a rotary table (not shown), and a groove 6 to be built up is provided on the upper surface of the metal base material 1. Reference numeral 2 is a supply pipe provided above the metal base material 1.
Is opened at one end and faces the groove 6 to be built up on the metal base material 1. The supply pipe 2 includes a gas supply branch pipe 2a and a metal powder supply branch pipe 2a.
b and diagonally downward, respectively. And
A laser device (not shown) is connected to the other end of the supply pipe 2 so that the laser beam 3 passes through the axis of the supply pipe 2, and is connected to the gas supply branch pipe 2a. An active gas supply device (not shown) and a metal powder supply device (not shown) are further connected to the metal powder supply branch pipe 2b.

Then, the supply pipe 2 is opposed to the groove 6 of the metal base material 1, and the metal base material 1 is rotated so that the groove 6 moves along the tip of the supply pipe 2. In this state, the laser device, the inert gas supply device, and the metal powder supply device are operated.

As a result, the laser beam 3 and the inert gas containing the metal powder 5 for overlaying, for example, the argon gas 4 are coaxially supplied to the groove 6 of the metal base material 1 from the supply pipe 2.

Thus, the metal powder 5 is melted by the laser beam 3 in the inert gas atmosphere of the argon gas 4 and built up in the groove 6.

In the above embodiment, the flow rate of argon gas, the inner diameter of the supply pipe 2, and the distance between the pipe tip and the metal base material 1 are set to the following ranges.

(1) Flow rate of argon gas: 0.5 to 10 / min (2) Supply pipe inner diameter: 1.1a to 3a when the build-up groove width is a (3) Distance between supply pipe tip and metal base material surface: within 5a In the range, if the flow rate of the argon gas is less than the above range, the sealing will be insufficient, and if it is too large, the antioxidation effect will be lost due to air entrapment. The diameter of the supply pipe is 1.
If it is smaller than 1a, the sealing is insufficient, and if it is larger than 3a, the gas flow is disturbed and the sealing is insufficient. Also,
Gas consumption increases. When the distance between the tip of the supply pipe and the surface of the metal base material is 5a or more, the argon gas is disturbed and air is entrained, so that the oxidation preventing effect is lost.

In the above-mentioned build-up method, the metal powder 5 for build-up is supplied onto the metal base material 1 coaxially with the laser beam 3 and the inert gas, so that the supply direction thereof is the upper surface of the metal base material 1. Even if it is slightly inclined with respect to, the overlaying work can be performed without any problem. The metal powder 5 is preheated in the supply pipe 2 for a relatively long time while being supplied coaxially with the laser beam 3.

According to the above-mentioned embodiment, the inert gas is constantly emitted by the laser beam 3.
Since it is supplied together with the metal powder 5, the molten overlay can be always wrapped in a fresh inert gas atmosphere.

In addition, as the metal powder for overlaying used in the above-mentioned examples, one having a trade name as Eatite was used. Further, nitrogen gas may be used instead of argon gas.

The enlarged photographs by the microscope shown in FIGS. 4 and 5 show the cross section of the overlay portion, and the photographs in FIG. 4 are those obtained by the conventional method.
FIG. 5 shows the case according to this embodiment. As is clear from both photographs, the conventional one shown in FIG. 4 has blow holes and slag entrainment, and the one shown in FIG. It was possible to obtain a good alloying part without the inclusion of holes and slag. Further, the surface unevenness was 0.5 to 1.0 mm in the conventional method, but it was 0.2 to 0.4 mm in the present example, and an extremely smooth surface could be obtained.

Further, according to the present embodiment, the metal powder 5 for build-up is coaxially supplied with the laser beam 3 and the inert gas onto the metal base material 1, so that the supply direction of these is the metal base material. 1
It is possible to perform the overlaying work without any problem even if the overlaying is slightly inclined with respect to the upper surface, and thereby the overlaying work in all directions in one plane can be efficiently performed.

Further, according to this embodiment, the metal powder 5 is supplied to the supply pipe 2.
It is possible to precisely control the preheating temperature of the metal powder by finely controlling the position of the passage for supplying the metal powder, the supply amount of the metal powder 5, the laser beam diameter on the surface of the metal base material, and the processing speed. Is. For this purpose, the laser output, beam diameter and processing speed are set to
For example, by setting conditions in which the Al base material is not excessively melted, and by adjusting the supply amount and the preheating temperature of the metal powder, the metal powder having a high melting point, such as tachylite # 6, is preheated to a high temperature, and the low melting point is set. The base material can be built up without excessive melting.

Another specific embodiment of the method of the present invention is shown in FIG.

In FIG. 3, 7 is a rotary table, and 8 is an oxidation prevention jig fixed to the rotary table 7. A work mounting jig 9 is mounted in the oxidation preventing jig 8, and the metal base material 10 to be built up is placed on the work mounting jig 9. Then, for example, using a gas supply pipe, the argon gas 4 is placed in the oxidation prevention jig 8.
An inert gas such as the above is introduced to make the state full with the inert gas.

In this state, the laser beam 3 is irradiated while supplying the metal powder for build-up on the metal base material 10 to generate a molten pool.
Since this molten pool is completely under an inert gas atmosphere, it does not cause a chemical reaction due to the mixture of air and the like.

〔The invention's effect〕

As seen from the specific examples in the above examples, in the method of the present invention,
The following operational effects peculiar to the present invention are achieved. That is, in an atmosphere of an inert gas, the laser beam and the overlay metal powder are coaxially supplied using a supply pipe onto the metal base material, and as a result, plasma is generated in the molten pool formed by the laser beam. Because the metal powder is directly supplied without being disturbed by the plasma gas flow as in the case of an arc, and it becomes embedded in the molten pool,
Gases containing an inert gas between the metal powders are reliably removed when they sneak in, and the invasion of gases into the molten pool can be prevented.

Therefore, the metal powder is smoothly melted and solidified to form an extremely uniform and good quality buildup layer.

Since the metal powder is supplied onto the metal base material in the atmosphere of the inert gas, the surface of the molten pool is surrounded by the inert gas atmosphere, and as a result, the metal powder is always kept in a fresh inert state by the laser beam. It will melt under a gas atmosphere.
Therefore, oxidation of the surface of the molten pool is prevented, blowholes and slag are not caught in the build-up portion, and the surface is smooth, so the quality of the build-up layer and the processing yield after build-up are good.

In the case of the conventional method in which the metal powder is placed on the metal base material in advance, it is very difficult to place the powder on the metal base material with high accuracy and at a constant height and at a uniform density. That is, if the pressure for compacting the powder from above changes, the packing density of the metal powder changes, which leads to a change in the buildup thickness and instability in the buildup quality.

On the other hand, in the overlaying method of the present invention, since the metal powder is directly supplied to the molten pool formed by the laser beam, the powder supply amount can be accurately and uniformly supplied by a high-precision powder feeder or the like. Therefore, it is possible to build a high quality overlay with a very stable and uniform thickness.

In the case of the conventional method in which the metal powder is placed on the metal base material in advance, the laser is first irradiated onto the metal powder placed in advance, but the metal powder at the top of the placed powder layer is, for example, spherical. Then, it is in point contact with the metal powder below it, and there is almost no heat conduction to the metal powder below, and since the heat capacity of the metal powder itself is also very small, the temperature rises sharply due to the laser energy irradiated, and melting occurs. To do. The molten metal at the top of the powder layer comes into contact with and covers the metal powder below it, and rapidly raises its temperature.

In this way, the metal powder in the lower portion is melted one after another, and the molten portion reaches the surface of the metal base material. The thus-formed fused portion thinly melts the surface of the metal base material by heat conduction to the metal base material, and as a result, a buildup layer metallurgically bonded to the base material is obtained. Since it is built up in such a process, the thickness and build-up quality of the build-up layer (such as melting of the metal base material to the build-up layer) depend largely on the thickness and packing density of the powder layer placed in advance. To be done. However, as described above, it is extremely difficult to make the height and packing density of the powder layer to be placed in advance constant, and thus such a conventional method causes variations in the thickness and quality of the overlay.

On the other hand, according to the overlaying method of the present invention, extremely stable overlaying with high quality is possible.

[Brief description of drawings]

FIG. 1 is a perspective view of a conventional method, FIG. 2 is an explanatory view showing an embodiment of the method of the present invention, FIG. 3 is an explanatory view showing another embodiment of the method of the present invention, FIG. 4 and FIG. FIG. 4 is an enlarged photograph of a metal structure of a built-up portion with a microscope. FIG. 4 shows the case of the conventional method and FIG. 5 shows the case of the present embodiment. 1 is a metal base material, 2 is a supply pipe, 3 is a laser beam, 4
Is argon gas, 5 is metal powder, 8 is an oxidation prevention jig,
9 is a work attachment jig, and 10 is a metal base material.

Claims (1)

[Claims] 1. A laser beam 3 in an inert gas atmosphere.
And a metal powder for build-up, which is coaxially supplied using a supply pipe 2 and supplied onto the metal base material 1.