JPS60177993A - Powder for plasma build-up welding - Google Patents

Abstract

PURPOSE:To produce metallic powder having excellent feedability and the smooth and nearly spherical surface forming a defectless bead part by spraying the melt of a stellite, cormonoy or Fe-Cr alloy into water or gas and cooling quickly the same as the metallic powder to be used for plasma build-up welding. CONSTITUTION:A stellite alloy consisting of Co as a base, contg. Cr, W and others and contg. <=2.50% B, or cormonoy alloy consisting of Ni as a base, contg. Cr, Mo, B, etc. and having <=6 B/C ratio by weight or Fe-Cr alloy contg. <35% Cr and <=0.21% (S+O+N) is used as metallic power for plasma build-up welding. All said alloys are made of the compsn. contg. respectively <=0.030% S and <=0.10% O2. The melt of such alloys is sprayed into water or inert gas or a mixture composed thereof by using an inert gas or reducing gas by which the metallic powder for plasma build-up welding having <2.5 long diameter/ short diameter, smooth surface and excellent feedability to a plasma arc torch is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to metal powder for plasma overlay welding, and in particular, the metal powder is fed into a plasma arc torch together with a powder conveyor, and (Material 11) is melted by the plasma arc formed between the
The present invention relates to a welding powder material for forming a predetermined built-up portion on the surface of the workpiece.

Overlay welding is an overlay welding method that improves the wear resistance, side heat resistance, or corrosion resistance of the surface of workpieces such as valves, pipes, and rolls by welding a specified overlay material (filler metal) to the workpiece. , has been known for a long time. As one of the overlay welding methods, an arc (pilot arc) generated at the tip of an electrode in a plasma arc torch is made into a plasma arc by plasma gas supplied into the torch. Plasma Arc, part 1.
The welding current supplied between the -ch and the predetermined workpiece plane A transfers the welding current from within the torch between those 1-ch and the workpiece, and also transfers the welding current into the plasma arc. There is a plasma build-up welding method in which a powder material to be built up on a member is supplied, the powder material is melted and guided to the surface of the workpiece, and a predetermined build-up is performed.

As mentioned above, this plasma overlay welding method uses a powder material as the overlay material, so it is possible to easily select a wide range of materials for the overlay material, and compared to the case where a bar material is used, It has attracted attention in recent years because it has excellent characteristics such as a faster melting rate and the ability to shorten welding time, and it is easy to fully automate the equipment.

Therefore, in such plasma overlay welding method,
In order to form a uniform overlay weld, in other words, a bead, and to form such a bead with good productivity, it is necessary to feed the powder material into the plasma arc torch together with the powder carrier gas. It is important to improve the welding properties and stabilize the feed rate. Furthermore, it is important to create a healthy bead part with a high center height and the desired buildup shape at the welding location where welding is to be done. However, conventional powder materials have not always been able to fully meet these demands.

Of course, attempts have been made to improve the shape of the heated part by selecting welding operations or welding conditions, but such welding operations or selection of welding conditions alone cannot solve the problem. It was impossible to make the heat shape sufficiently sound.

The present invention has been made against the background of the above-mentioned circumstances, and its purpose is to provide excellent feedability, stable feedability, and a sound heating system. It is an object of the present invention to provide a powder for plasma overlay welding which can provide a high level of performance.

In order to achieve this object, the present invention uses the above-mentioned powder for plasma overlay welding, its S (sulfur)
The moon has a smooth surface and a substantially spherical shape so that the content of 0 (oxygen) is 0.030% by weight or less and the content of 0 (oxygen) is 0.10% by weight or less, and Long diameter/
The structure is such that the value of the short axis is 2.5 or less.

By using the powder material according to the present invention, the ability of the powder carrier gas to feed the powder to the plasma arc chamber can be further improved, and the material can be uniformly and stably supplied. As a result, a uniform heated part can be formed effectively and with good productivity, and the shape of the heated part can also be improved from the viewpoint of powder materials, and a sound bead part can be effectively formed. That's what happened.

That is, according to the present invention, the length/breadth ratio of the spherical powder is set to 2.5 or less, and the S content is set to 0.0.
By setting the content of 0 to 30% by weight or less and the content of 0 to 0.10% by weight or less, a good heat shape can be stably obtained, and even if the overlay welding part is inclined, such Due to the inclination, the molten powder material hardly sags, so that it is possible to advantageously form a sound solid part.

Incidentally, the powder material according to the present invention can be used in an appropriate size depending on the welding equipment, welding conditions, etc., but generally the size is about -60 to +300 meters. will be suitably used.

Powder particles of such size are formed to have a smooth surface and a substantially spherical shape; When the ratio of a certain major axis to the short axis, which is the smallest diametrical length, i.e., the value of major axis/short axis, exceeds 2°5, the shape of the heated part that is formed becomes unstable. and S contained in such powder particles.
If the amount exceeds 0.030 wt. sagging due to the inclination of the welded part, causing problems such as irregularly shaped heat.

Chemical compositions that provide a powder material that satisfies the conditions according to the present invention and are used for plasma overlay welding include stellite (Co-based) and colmonoid (Co-based).
There are three component systems, Ni (Heath) and Fe Cr, and in the present invention, it is desirable that these component systems have the following composition ratios.

First, in the case of Co-based stellite, C (carbon): 0.2 to 3.0% by weight, Cr (chromium): 20 to 3
5% by weight, W (tungsten): 2-14% by weight, Ni
0-25% by weight, Mo (molybdenum) 20-10% by weight, Si: 0-4% by weight, Mn (manganese): 0-2% by weight, Fe (iron): 0-6% by weight , S≦0
．． It is desirable to form a powder material with a chemical composition of 0.030% by weight, 0≦0.10% by weight, and Co (cobalt): the balance.

Incidentally, among these alloy components, C is the build-up part (material)
Although it is an effective element in improving the strength of
Adding too much of it warps and deteriorates the brittleness of the built-up portion. Further, Cr and W are each effective in improving hardness, and Cr is also effective in improving heat resistance. Similarly, Mo, C.

are effective elements for improving hardness, and the former is also effective for improving toughness, and the latter is effective for improving heat resistance. In addition, it is desirable to add Si as a deoxidizing agent,
Mn is effective in improving cracking resistance, and Ni,
Fe is a filler element that makes the present composition system inexpensive.

By using each of these metal elements within the above-mentioned ranges, it is possible to obtain a powder for plasma overlay welding that has the desired physical properties. and 0 have a great influence on the flow of the molten powder (hot water) melted by the plasma arc, and by keeping the content below the above value, the overlay weldability is made good, It has the effect of increasing the hardness and toughness of welded parts and reducing cracking. Moreover, by lowering the S and O contents, the surface tension of the cold metal air increases, which has the advantage of effectively smoothing the surface when forming powder by the spraying method described later.

In addition, in such a stellite-based chemical composition, it is desirable that the powder material further contains up to 2.50% by weight of B (boron), and by adding 0% of this B, the powder material is formed. In addition to lowering the melting point of the molten metal and effectively effecting its spheroidization, the melting of the overlay welding part of the matrix can be effectively controlled, making it possible to easily obtain a sound welded part. .

In addition, due to the chemical composition of the colmonoid system of Ni hese,
When forming the powder according to the invention, C: 0.1~
3.0% by weight, B: 0-3.5% by weight, Cr: 1-30
Weight%, Si (silicon): 0.1 to 7.0% by weight, Mo
:O~20.0% by weight, Cu (copper): 0~5% by weight,
Ti (titanium) 20-5% by weight, Mn: 0-4, market weight W: = O-IO weight%, Fe: 0-6% by weight,
S≦0.030% by weight, O12, 10% by weight, and N
It is desirable to have a composition consisting of i: the remainder.

Each of these components is used in the same meaning as mentioned above, and within the desired range of use, improves the physical properties of the overlay weld formed on the target base material. Of these components, Si is an effective element for improving hardness and lowering the melting point, while Cu and Ti are effective for improving the corrosion resistance of welded parts. In addition to being an effective element, Ti also improves welding stability. In addition, by setting the B/C value to 6 or less in these chemical compositions, there are benefits of making the overlay weld extremely hard, making it easier to melt, and lowering the melting point. Also, M
N is effective for improving heat resistance, and Mo is effective for improving hardness.

Furthermore, when forming the powder material according to the present invention with a chemical composition of FC-Cr system, C: o, os ~
4.0ffiffi%, Cr: 0.5-35% by weight, N
i: 0-15% by weight, Si: 0-5% by weight, Mn: 0
~4% by weight, MO: 0 to 15% by weight, S≦0.030% by weight, O12, 10% by weight, N (nitrogen) 50.10% by weight, and Fe: the balance. By adopting this composition range, it is possible to effectively produce an overlay weld having desirable physical properties.

In addition, in such a composition, Ni is an element effective in improving brittleness and viscosity, and is also an element related to N Lj properties, and its excessive presence can increase the amount of scum on the bead surface. This increases the amount of heat and deteriorates the properties of the weld. In particular, the sum of S, 0, and N (S+0−I
It is desirable to adjust the N) content to 0.210% by weight or less, thereby improving weldability (cracking) and toughness, and facilitating spheroidization.

A powder material having a substantially spherical shape having such a chemical composition and having a smooth surface that satisfies the conditions according to the present invention described above is generally effectively produced by the following spraying method. Is possible.

That is, while the molten metal having the above-mentioned chemical composition is allowed to flow down, an inert gas or reducing gas is used as the atomizing gas to spray the molten metal into fine droplets. The target powder is produced by cooling the droplet particles with water or gas, or with a mixture of water and gas, so that the particle surface becomes smooth and substantially smooth. As a result, a spherical powder is obtained. In particular, it is suitable for such a spraying method to use water vapor as the coolant.

In order to clarify the present invention more specifically, some examples of the present invention will be given below, but the present invention should not be construed in any way in a limited manner by the description of these examples. It will be obvious to those skilled in the art that the present invention includes various modified embodiments without departing from the spirit of the invention. Note that all percentages in the examples are expressed on a weight basis.

Example 1 Various powder materials were obtained using various molten stellite metals having the chemical compositions shown in Table 1 below by a method according to a conventional spraying method. Note that Ar is used as the atomizing gas.
was used, and cooling of the droplet particles was performed by a mixture of Ar and water.

Regarding the various powder materials obtained in this way, the major axis/
In addition to determining the minor diameter ratio, the feedability and weldability of these powder materials were evaluated, and the results are shown in Table 2. In addition, the feeding performance is as follows: The material is dropped from the hopper through a 3-diameter nozzle, and a gear is placed at the lower end of the nozzle to rotate it at a speed of 2 Orpm to cause the material to fall into the conveying pipe. The weldability was evaluated using a build-up test for automobile valves by determining whether the bead shape of the build-up part was sound.

As is clear from the results in Tables 1 and 2, in the powder materials of 11k1.1 to 9 according to the present invention, the S content is 0.030% or less, and the 0 content is 0.10%. % or less, and the length/breadth ratio is also 2.5 or less, indicating good results in terms of feedability and weldability. In addition, it was observed that the back surfaces of the powder materials Nos. 10 to 2 were significantly smoothed by the addition of a predetermined amount of B.

On the other hand, in floors 7 to 9 of the comparative example, the S content and O content are outside the range of the present invention, and the obtained powder also has a length/breadth ratio of 2. .5 exceeds 5, the feedability is poor, and the build-up test results for weldability evaluation show that the powder materials No. 11 and No. 12 are particularly poor due to island flow. In this case, the bead shape was significantly deteriorated, and it was not possible to form the intended good built-up portion.

6 7 2 Table 8 Example 2 Colmonoid metal solutions '/A having various chemical compositions shown in Table 3 below were powdered by the spraying method in the same manner as in Example 1, and various powders were obtained. The materials were evaluated for their feedability, diameter/minor diameter ratio, and weldability (bead shape), and the results are shown in Table 4.

As is clear from the results in Tables 3 and 4, according to the present invention, the S content in the powder material is 0.030% or less, the 0 content is 0.10% or less, and the length/breadth ratio is 2.
For those that were 5 or less (No, 21 to 33),
Both feedability and weldability (heat shape) have been significantly improved, and among those chemical components, the surface smoothness has also been significantly improved for those with a B/C ratio of 61u or less. It was confirmed that the particles were spherical.

On the other hand, if the S content in the particles is high, the 0 content is high, or the major axis/minor axis ratio exceeds the specified value of the present invention, feedability and/or weldability will deteriorate. It gets significantly worse.

9 0 Table 4 1 Example 3 Powder materials were produced by a spraying method according to the method of Example 1 using various Fe-Cr alloy hot water shown in Table 5 below, and the fM of various types was The powder materials were evaluated in the same manner as in Example 1, and the results are shown in Table 6.

As is clear from the results in Tables 5 and 6, the powders No. 41 to 49 according to the present invention provide good feedability and a sound heat shape (weldability). Ta. Moreover, the N content in each of these particles is 0.1
Since it is said to be 0% or less, it is believed that the scum on the surface of the beets is extremely low and healthy.

On the other hand, the powder materials with positive numbers 50 to 52 of the comparative examples had poor feedability and/or bead shape, especially No.
For particles No. 51 and 52, it was observed that a large amount of scum was formed on the bead surface.

2

Claims (1)

[Claims] (]) The powder is fed into a plasma arc torch together with a powder carrier gas, and is melted by the plasma arc formed between the torch and a predetermined workpiece to form a powder on the surface of the workpiece. The welding powder material for forming a predetermined built-up part has an S content of 0.030% by weight or less, 0.
plasma meat having a content of 0.10% by weight or less, a smooth surface, a substantially spherical shape, and a length/breadth axis value of 2.5 or less. Powder for welding. (2) The chemical composition of the powder material is C: 0.2 to 3.
0% by weight, Cr: 20-35% by weight, W: 2-14% by weight, Ni: (]-25% by weight, Mo 20-10% by weight,
Si: 0~4% by weight, Mn: 0~2% by weight, Fe 20~
6% by weight, S≦0.030% by weight, 0≦0.10% by weight
, and CO: the balance, the powder for plasma overlay welding according to claim 1. (3) The plasma build-up welding powder according to claim 2, wherein the powder material further contains up to 2.50% B by market weight. (4) The chemical composition of the powder material is C: 0.1 to 3.
0% by weight, Bl~3.5% by weight, Cr: 1~30% by weight
, Si: 0.1-7.0% by weight, MO: 0-20.0% by weight, Cu: 0-5% by weight, Ti: 0-5% by weight, Mn
: 0-4% by weight, W: 0-10% by weight, Fe: 0-6% by weight, S≦(IO30% by weight, 0≦0.10% by weight,
and Ni: the balance for plasma overlay welding according to claim 1. (5) The powder for plasma overlay welding according to claim 4, wherein the powder material contains a predetermined proportion of B and C so as to satisfy the relationship B/C≦6. (6) The chemical composition of the powder material is c:o, o5-4.
0% by weight, Cr: 0.5-35% by weight, Ni: 0-15
Weight%, Si: 0-5% by weight, Mn: 0-4 City weight M
O: 0 to 15% by weight, S≦0.030% by weight, 0≦0.
10% by weight, N≦0.10% by market weight, and Fe: balance, the powder for plasma overlay welding according to claim 1. (7) The powder for plasma overlay welding according to claim 6, wherein the powder material contains a predetermined proportion of S, 0, and N so as to satisfy the following formula: % formula %. (8) Using the above powder material, inert gas, or reducing gas as a spray gaff, spraying a specified metal/8 hot water, and cooling the spray particles with water, dregs, or a mixture of water and gas. The powder for plasma build-up welding according to any one of claims 1 to 7, which is made into a spherical shape by using the above method.