JPH03221269A - High-alloy member and method for welding this material - Google Patents

Abstract

PURPOSE:To prevent the deterioration in the corrosion resistance by the scale formation of a weld zone by forming an Mo film or Mo-contg. film in the position corresponding to at least the heat affected zone at the time of welding of high-alloy members. CONSTITUTION:Mo evaporates from the Mo film or Mo-contg. film and bonds to the oxygen in the atmosphere to form an oxide when the film is heated at the time of welding. The oxygen partial pressure in the atmosphere, therefore, decreases in the periphery of the heat affected zone and since the quantity of the oxygen taken into welding scale decreases, the formation of the welding scale on the metal surface which is a substrate is suppressed and the concn. of the Cr in the welding scale is increased. The constant scale is thus formed. The corrosion resistance is, therefore, improved even if the removal of the weld scale is not executed. Since the Mo has the high vapor pressure of the oxide thereof and evaporates rapidly, the coating of the surface of the Mo existing on the surface of the high-alloy member with the oxide of the Mo is obviated and, therefore, the deterioration in the corrosion resistance at the time of multilayered welding is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a high alloy member and a welding method thereof. More specifically, the present invention provides a high-alloy member and a high-alloy member capable of preventing deterioration in corrosion resistance of weld scale generated at welded parts of various devices, piping, structures, etc., and improving the corrosion resistance. Regarding the welding method.

(Prior Art) When equipment, piping, structures, etc. using high alloy members such as stainless steel members or high alloy members are used in corrosive environments, weld scale generation parts (hereinafter referred to as This means that the corrosion resistance of the heat-affected zone J (also referred to as heat-affected zone J) deteriorates significantly, and susceptibility to corrosion locally increases, such as pitting corrosion and crevice corrosion.In other words, corrosion resistance deteriorates and corrosion occurs during use. The equipment has been damaged and is causing major equipment or operational problems.
This has been known empirically for some time.

In particular, high-alloy tubes for line pipes or chemical industry piping are often used to transport corrosive aqueous solutions containing halide ions and are circumferentially welded at the construction site. At this time, since the welded part and its vicinity are heated, the part is oxidized and weld scale is generated.

Therefore, the main ll! of such high alloy tubes! The problem is ensuring corrosion resistance, that is, ensuring the corrosion resistance of the welded parts.

Conventionally, as a means of preventing the occurrence of such corrosion, it has been widely used to remove weld scale by pickling the weld scale generation area after welding, or by grinding it with a grinder, wire brush, etc. It was done.

These methods have been widely used because they allow welding scale to be removed relatively easily and reliably. In other words, in the case of circumferential welding of pipes,
Weld scale generated on the outer surface of the pipe can be easily and reliably removed by pickling or the like after welding. However, for example, it is virtually impossible to apply these methods to the inner surface of a pipe, especially the inner surface of a small-diameter pipe, after welding has been completed, making it impossible to maintain the corrosion resistance of the welded scale-generating area, which has been a problem for some time. It had become.

Note that by using a high-grade material with higher corrosion resistance than the base metal as the welding material, it is possible to ensure the same corrosion resistance as the base metal even if weld scale occurs, but this method is not recommended. This not only increases costs, but also makes it impossible to maintain the corrosion resistance of the heat-affected zone during welding. In particular, it is virtually impossible to prevent the formation of scale on the inner surface of a small-diameter pipe, and it has been desired to develop some kind of countermeasure, such as a pretreatment method before welding that prevents scale formation.

In addition, as a method for preventing weld scale formation on the inner surface of medium-sized and large-diameter pipes, for example, a balloon-type air bag is placed inside the pipe before and after the welded part, and the inner surface is shielded with an inert gas such as N or Ar. A gas shielding method for welding the outer circumferential surface was known, but the shielding condition varied depending on work conditions, etc., and as long as it was carried out on-site, it was necessary to ensure that the area near the welded area was properly welded to the extent that welding scale could be reliably prevented from forming. It was not possible to lower the oxygen partial pressure.

Therefore, the inventors of the present invention previously disclosed in Japanese Patent Application Laid-Open No. 63-238287 that ``a high-alloy tube containing 13% by weight or more of chromium has a potential less noble than the above-mentioned high alloy on the inner surface of the tube end. We proposed a high-alloy tube with a coating layer mainly made of a metal that has a stronger affinity for oxygen, and furthermore, by butting such tubes together and then welding their ends circumferentially, welding scale could be removed without having to remove the weld scale. We also proposed a means to reliably prevent the deterioration of the corrosion resistance of the weld scale on the inner surface of the tube.

This means uses, for example, AQ, Si, or Mn as the metal, and takes advantage of the fact that these metals are oxidized more preferentially than Cr during welding.

(Problems to be Solved by the Invention) However, although the means proposed in JP-A No. 63-238287 is certainly a means that can prevent deterioration of the corrosion resistance of the welded portion of high alloy pipes, Subsequent studies by the present inventors have revealed that when performing thermal spraying or plating as a method, there is a problem in that special equipment is required for pipe end treatment at the welding site.

Therefore, the inventors of the present invention have made further efforts and have previously published Japanese Patent Application No. 63-28315, in which the particle size is 2004 or less. 1g, 8Q, to Si, Ti, Cr, M
Paddy powder containing one or more of n, Pe and Zr in 0.5~
A means of applying a water glass suspension containing 50% by weight to a portion corresponding to the heat affected zone of a high alloy tube in advance and welding the same,
In addition, according to Japanese Patent Application No. 63-288529, high-alloy tubes having an IW layer of 10+*g/s or more, which is made by coating and drying a chromate treatment liquid on the inner circumferential surface of the tube in the heat-affected zone during circumferential welding, are butted together. We proposed methods for circumferential welding.

Among these, the method proposed in Japanese Patent Application No. 63-28315 is that metals such as ceramics are preferentially oxidized during welding because they tend to generate oxides more easily than the base material of the high-alloy tube. By suppressing the oxidation of the high alloy tube that is the base material,
This is a means to prevent deterioration of the corrosion resistance of high alloy pipes due to oxide scale formation.

According to the means of the prior invention described above, it is possible to prevent deterioration of corrosion resistance due to the formation of weld scale in the welded portion.

However, in recent years, with the increase in on-site construction of stainless steel hot water pipes and high alloy line pipes in buildings, for example, deterioration of the corrosion resistance of welded parts due to the formation of weld scale has become a problem, and there is a growing need for improvement. It has become. That is, since the welding is carried out on-site, it is difficult to reliably control the welding conditions, and it may not be possible to completely prevent the deterioration of the corrosion resistance of the weld scale-generating part.

Furthermore, according to the studies of the present inventors, the above-mentioned patent application No. 1983-
It has also been found that the method proposed in No. 28315 has the following problems. In other words, the oxides of metals such as Mg are heated to a temperature (1
Since it is stable without being decomposed at temperatures below 400°C, if oxides are formed on the surface of the metal powder, subsequent oxidation of the metal powder will be suppressed.

As described above, since the metal powder becomes difficult to be oxidized, the effect of preventing deterioration of the corrosion resistance of the high alloy tube that is the base material is reduced.

Therefore, for example, in circumferential welding of high-alloy pipes or welding of thick-walled parts, which is performed by so-called multi-layer GT welding, in which welding is usually performed in two or more passes, the thermal history of the same part is different for each bus. Therefore, the coating effect of the metal powder may be reduced after the second bath.

In other words, no means has hitherto existed that can reliably prevent the deterioration of the corrosion resistance of weld scale generated in welded parts of high-alloy members.

SUMMARY OF THE INVENTION An object of the present invention is to provide a high alloy member and welding thereof that can improve the corrosion resistance of the weld scale in the welded part of the high alloy member and reliably prevent deterioration of the corrosion resistance of the heat affected zone during welding. It is to provide law and furthermore,
It is an object of the present invention to provide a high-alloy member and a welding method for the same, in which the corrosion resistance of the multi-layer welded part is hardly deteriorated even when the high-alloy member is butt welded by multi-layer welding.

(Means for Solving the Problems) In order to solve the above problems, the present inventors have conducted various studies and found that the higher the Mo content in the high-alloy member, the better the corrosion resistance caused by welding scale formation. (2) The Cr concentration in the weld scale made of oxides is high, and it was found that the weld scale acts effectively as a protective film even in a chloride solution.

Therefore, the present inventors conducted a detailed study on the behavior of Mo during welding of high-alloy members.

As a result, Mo oxide has a high flower pressure at high temperatures, and when it combines with oxygen in the atmosphere and becomes an oxide, it immediately vaporizes, so before welding, Mo oxide is formed into a heat-affected zone during welding. If a gap exists in the part, this Mo and oxygen will combine preferentially during welding, thereby reducing the oxygen concentration in the heat affected zone and its vicinity during welding, suppressing the formation of weld scale, C in relative welding scale
It was found that the degree of rlJ increased.

Furthermore, in the means proposed in Japanese Patent Application Nos. 63-28315, the oxidation-preventing effect of applying metal powder such as Mg decreases in the case of multilayer welding because the surface of the metal powder is covered with the oxide. . Therefore, by making a metal whose surface is not covered with oxides, that is, MO whose oxide has a high vapor pressure, exist in a region corresponding to the heat-affected zone during welding before welding, it is possible to It has been found that it is possible to suppress the formation of oxide scale in circumferential welds, and also to prevent deterioration of the corrosion resistance of multilayer welds.

Therefore, as a result of further study, the present inventors determined that M
In order to make the heat-affected zone exist during welding, by using a member that has a Mo coating or a heat-containing coating applied to the area concerned, and welding such a member at the area where the coating is applied, deterioration of the corrosion resistance of the heat-affected zone during welding is prevented. We have discovered that it is possible to obtain even better corrosion resistance than the means proposed by fN in JP-A No. 63-238287, and that it is also possible to prevent deterioration of the corrosion resistance of multi-layer welded parts. Completed the invention.

Here, the gist of the present invention is to apply a No coating or an Ilo coating at least to a portion corresponding to a heat affected zone during welding.
It is a high alloy member characterized by having a containing coating.

In the above-mentioned invention, the "rMo coating" refers to (1) a Mo powder coated coating applied to the surface of the high alloy member directly or via a Ni plating layer or a Ni-based alloy plating layer as a base, or (2) the above-mentioned Mo with a thickness of 0.1μ or more applied directly to the surface of a high alloy member or through a Ni plating layer or Ni-based alloy plating layer as a base.
It is preferable that it is a molten salt plating film, and furthermore, in the above-mentioned invention, the rMo-containing film is: (i) a Ni plating layer or a Ni-based alloy plating applied directly or as a base to the surface of the high alloy member; applied through a layer, with a thickness of 0.1μ or more, containing 5% by weight of MO
Ni-Mo alloy containing 40% by weight or more, Fe
- a plating film of Mo alloy or Pe-Ni-Mo alloy;
- A powder-based Ni plating film or a Ni-based alloy plating film containing 5% by weight or more and 50% or less of Mo powder, or ■ A Ni plating layer as a base on the surface of a high-alloy member. or applied through a Ni-based alloy plating layer with a thickness of 0.1
μ or more and a Mo powder-dispersed Ni plating film or a Ni-based alloy plating film containing Mo powder in an amount of 5% to 50% by weight is preferable.

In these aspects of the present invention, it is also preferable that the Ni plating layer or Ni-based alloy plating layer as the base has a thickness of IIJa or more.

Furthermore, another gist of the present invention is that the high alloy member according to the present invention is welded to another member at a portion where the Mo coating or Mo-containing coating is applied. This is a method of welding parts.

In the present invention, the term "heat-affected zone" refers to a part where weld scale is generated during welding, and although it varies depending on the dimensions of the parts to be welded, - within the shell, there are several centimeters from the end of the parts to be welded. -, for example, within 10 cm.

In addition, in the present invention, "high alloy member" refers to high alloy,
For example, stainless steel such as 5US316L or 329J2L containing 12% by weight or more of C, FeJI alloy, or Ni-based alloy containing 12% or more of Cr such as Aloy 825, Hastelloy (registered trademark), etc. Refers to various devices, pipes, tanks, reaction vessels, and structures.

Furthermore, in the present invention, the high-alloy member has a gate 0 coating or a Mo-containing coating not only in the above-mentioned "heat-affected zone" but also in its vicinity, for example, in a region where welding scale does not form but is affected by heat. In the present invention, the term "at least the heat-affected zone during welding" is used to clarify this point.

Furthermore, in the present invention, the "other member" may be a high alloy member according to the present invention, or may be a normal member.

(Function) Hereinafter, the present invention will be explained in detail along with the function and effect. In this specification, "1%" means "wt%" unless otherwise specified.

First, the high alloy member according to the present invention will be explained.

In the high-alloy member according to the present invention, an interlayer film or a Mo-containing film is formed in advance at least in a region corresponding to a heat-affected zone during welding before welding. Therefore, when the relevant part is heated during welding, as described above, the gate 0 vaporizes from the gate 0 cover or the Mo-containing coating and preferentially combines with oxygen in the atmosphere to become an oxide. Therefore, the partial pressure of oxygen in the atmosphere is sufficiently lowered locally around the heat-affected zone during welding, and the amount of oxygen taken into the welding scale is reduced, which prevents the formation of welding scale on the surface of the underlying metal. At the same time, the Cr11 degree in the generated welding scale is relatively increased, and a stable scale is generated.

Therefore, the welding scale generated with heating is
Since the resulting Cr-rich oxide film acts as a protective film for corrosion protection, the corrosion resistance of the heat-affected zone is significantly improved even if weld scale is not removed after welding.

In addition, as mentioned above, the vapor pressure of Mo's oxide is high and it vaporizes immediately, so the surface of molybdenum that is not yet oxidized and exists on the surface of the high-alloy material is affected by the oxide of No. never be covered. Therefore, it is also possible to prevent deterioration of corrosion resistance during multilayer welding.

As described above, in the present invention, at least the part corresponding to the heat affected zone during welding is coated with the pubic membrane or Mo.
By forming a containing film, the gate 〇 is made to exist,
The purpose is to prevent deterioration of the corrosion resistance of the heat-affected zone during welding, and various embodiments can be exemplified for the above-mentioned No coating or) lo-containing coating and its formation. Therefore, below, these coatings will be explained in detail using the following items (1) to (2).

In addition, in the following (1) to (2) and (2), embodiments are also shown in which a Ni plating layer or a Ni-based alloy plating layer is provided on the surface of the high alloy member as a base for the Mo coating or Mo-containing coating. Since the effects on the Mo coating, Mo-containing coating, and high-alloy members are the same, the Ni plating layer or Ni-based alloy plating layer as the base will be described in detail in Section 2. .

A coating mainly composed of Mo powder is provided at least in a region corresponding to a heat affected zone during welding. The particle size of this Mo powder is not particularly limited, but from the viewpoint of ensuring sufficient antioxidant effect and coating workability, it is set at 100 m.
It is desirable that IO/j is less than or equal to
It is less than lI. In addition, the amount of adhesion may be changed appropriately according to the welding heat input, the number of buses in the case of multi-layer welding, and the above-mentioned grain size, etc., and there is no need to limit it, but - 1 to 100 Dec for boat fishing ”, preferably 10 mg/c
m" or more, the effects of the present invention can be reliably obtained.

Further, as a coating method, a method of mixing it with a liquid and spraying or coating it is effective from the viewpoint of workability and ensuring a uniform coating. Such a liquid is not limited to a specific one, as long as it can sufficiently hold the Mo powder and ensure sprayability and coating properties.

For example, in the case of coating method, water glass (NazO/5i
An example is an aqueous solution containing 10 to 90% of Oz = 2 to 3).

In addition, such Mo powder is exemplified by a powder with a purity of 99% or more that is commercially available as a reagent (for example, Mo powder commercially available from Wako Pure Chemical Industries, Ltd.), but is not limited to this. Needless to say, it is not a thing.

In addition to the No powder, metal carbonates, sulfates, oxides, fluorides, or organic substances may be added to this liquid in order to improve adhesion to the surface of high-alloy materials and promote the dispersion of the Mo powder. The coating layer may be made mainly of Mo powder.

Furthermore, this coating layer is calcined (low-temperature baking) after application.
Although it is desirable to form a dry coating film from the viewpoint of workability, it is of course possible to leave the coating film as it is sprayed or applied. Even if the Mo coating is peeled off or damaged for some reason, it can be easily repaired (coated) on-site, resulting in extremely good workability.

In this way, at least a portion of the high alloy member according to the present invention corresponding to the heat-affected zone during welding is provided with a powder coating.

For Mo plating by molten salt electrolysis, conventional methods may be used. Na, MoO, t
B2 is added as a modifier to control the viscosity and melting point of the bath.
Mo plating can be performed by using a plating bath containing 01 and NazBaOq. That is, electroplating can be considered as a means of coating MO on at least the portion corresponding to the heat-affected zone during welding of the high alloy member, but electroplating of Mo alone is performed because the equilibrium potential of Mo and Molide ions is hydrogen. Since the potential is less base than the equilibrium potential of the electrode reaction, hydrogen is generated in the plating method using aqueous solution electrolysis, making it impossible to obtain a No plating film.However, when using the molten salt electrolytic plating method (molten salt plating) , it is possible to plate Mo alone without generating hydrogen as described above.Therefore, it is possible to perform plating of Mo alone in high-alloy parts at least on the parts corresponding to the heat-affected zone during welding. By using a member and welding the member, it is possible to prevent deterioration of the corrosion resistance of the heat affected zone during welding.

The thickness of the plating layer can be adjusted, for example, by changing the electrolysis time and current density, and if the thickness of the plating layer is less than 0.1μ, local deterioration of corrosion resistance is unavoidable. Therefore, it is desirable to set it to 0.1- or more.The thicker the plating film, the better, but in reality, the plating process takes an extremely long time, and the effect of improving corrosion resistance is saturated. Therefore, it is desirable that the upper limit is about 100-.

In this way, at least the portion corresponding to the heat affected zone during welding of the high alloy member according to the present invention has a thickness of 0.19.
A Mo molten salt plating film of m or more is provided.

Although it is ideal to perform plating of Mo alone as in (2) above, it is also possible to perform plating of a Mo alloy containing Pe, Ni, Cr, etc.

Therefore, at least the area corresponding to the heat affected zone during welding of the high-alloy system member is plated with an alloy containing MO, that is, electroplating or electroless plating of Nj-Mo alloy, Fe
-Mo alloy or Fe-NI-Mo alloy is electroplated.

Therefore, in the present invention, the reason why the Mo content in each alloy is limited will be explained.

If the Mo content in each alloy is less than 5.0%, the amount of oxygen combined with MO and reduced is small, so the amount of oxygen in the oxide scale of the weld metal cannot be sufficiently reduced, and the weld scale There is a risk that deterioration of the corrosion resistance of the material may be unavoidable.

Further, the higher the Mo content, the better, but since it is practically difficult to perform plating containing more than 40% Mo, it was limited to 40% or less. Therefore, it is desirable to limit the No content to 5.0 to 40%.

Furthermore, the composition other than Mo in each alloy is not particularly limited; for example, in the case of a Ni-Mo alloy, P, B
, H, Fe, Co, Cr-W, etc., and also Re-
In the case of Mo alloy, Ni, Co, Cr, P, W
etc., and in the case of FeNi-Mo alloy, C01Cr
, P, W, , B, etc. are exemplified.

Also, especially Ni-? In the case of Io alloy, it can be performed not only by electroplating but also by electroless plating, but this N
If the i-Mo alloy contains only unavoidable impurities other than Ni and MO, Ni
will be contained approximately 95.0 to 60%, but Ni
Considering that Ni itself has the effect of suppressing oxidation of the heat-affected zone, it is even more preferable to have a high Ni content like this alloy.

Furthermore, 111-M0! in a phosphoric acid bath or in a dimethylamine borane bath! In order to perform electrolytic plating, a small amount of P is required.
Alternatively, it is desirable that B be included in the Ni-Mo alloy, but the content thereof is approximately 3.0% or less. It goes without saying that the film thickness can be adjusted by adjusting the dipping time and the like.

Note that the electroplating of the Fe--Mo alloy or the Fe--Ni--Mo alloy may be performed by any well-known means and does not require any limitations.

Next, the reason why it is desirable to limit the plating film thickness to 0.1 p or more in the present invention will be explained.

The thickness of the plating was set to be 0.1p or more, since if it was less than 0.1μ, local deterioration of corrosion resistance might be unavoidable. The thicker the plating film, the better, but in reality, the plating process takes an extremely long time, and the corrosion resistance improvement effect is saturated, so the upper limit is 100 pa.
It is desirable that the

In this way, at least the part corresponding to the heat affected zone of the welded part of the high alloy member according to the present invention has a thickness of 0.1
Ni-No alloy, Pe-Mo alloy or FeNi-Mo containing 5% or more and 40% or more of Mo
An alloy plating coating is provided.

In general, in dispersion plating, the particles transported to the growing plating surface are adsorbed, and then physically bonded by the precipitated metal and embedded in the matrix one after another to form fibrous or particulate particles. This is plating of a composite material having a dispersed phase such as Therefore, the eutectoid particles literally become a dispersed phase randomly distributed within the metal matrix.

Moreover, part of each fine particle on the surface of the plating film is embedded in the metal, and the rest is exposed on the surface of the film.

In the present invention, Ni is used as the base material supporting the HO powder.
From the viewpoint of ensuring corrosion resistance, it is preferable to use plating or, for example, Ni-based alloy plating containing Co or the like. In this way, in the present invention, a former powder dispersed Ni plating film or a Ni-based alloy plating film is used, but in order to form these films, for example, MO silk powder dispersion is added to a Ni plating bath or a Ni-based alloy plating bath. It is sufficient to leave it cloudy and perform electroplating or electroless plating.

Furthermore, in the present invention, the reason why dispersion plating is used is as follows: (1) Mo particles are uniformly dispersed in the matrix of Nt or Ni-based alloy, so that the strain accumulated in the plating layer as the plating is formed is alleviated; The plating is less likely to crack. Therefore, it becomes possible to perform thick plating. Therefore, the amount of No contained in the plating layer can be significantly increased compared to thin alloy plating, and the effect of preventing deterioration of corrosion resistance of Mo can be sufficiently maintained.

■Also, in this way, MO particles can be made of Ni metal or N
By dispersing it in the matrix of the i-based alloy, the strain in the plating layer due to the thermal history during welding is alleviated, making it difficult for cranks to enter the plating. Since it can be formed on the surface, it is possible to form a plating film that can sufficiently withstand several welding passes.

It is from.

Next, in the present invention, the content of MO\A powder in the Ni plating film or Ni-based alloy plating film is 5% or more and 50%.
The reason why it is desirable to limit the following will be explained. If the MO content is less than 5%, the oxygen potential near the heat-affected zone during welding cannot be sufficiently lowered due to the small amount of oxygen that combines with MO, and even if the plating layer is thick, the corrosion resistance of the weld scale area will deteriorate. On the other hand, the higher the content, the more effective it is in preventing deterioration of the corrosion resistance of the weld scale part, but if it exceeds 50%, the dispersion plating with good adhesion may fail. This is because there is a possibility that it will not be obtained. Therefore, it is desirable to limit the content of Mo powder dispersed in the Ni plating film or Ni-based alloy plating film to 5% or more and 50% or less.

Further, the particle size of the Mo powder is desirably 1- or more and 100/jI or less. This is because if it is less than 1-1, the Mo powder will aggregate in the plating film and become coarse, and the effect of making the powder finer will be lost.
This is because if it exceeds μ, uniformly dispersed plating may not be obtained. In addition, more preferably 1μ
It is not less than lOμ.

Also, the reason why it is desirable to limit the thickness of the Ni plating film or Ni-based alloy plating film to 1 p or more will be explained. If it is less than l-, Mo
This is because the corrosion resistance of the welded scale-generating portion may inevitably deteriorate because it is consumed by combining with oxygen. Although there is no particular need to set an upper limit, it is desirable that it be 100 Da or less because plating takes a long time and the effect is saturated.

In addition, compared to, for example, the plating film of Ni-No alloy in the above item (2), the lower limit of the preferable range of the plating film thickness is 1p.
The reason for the high value of m is that in the present invention, corrosion resistance must be ensured by dispersing Mo powder (not by plating).

As described above, at least in the region corresponding to the heat affected zone during welding of the high alloy member according to the present invention, a Mo powder having a thickness of 1 μ or more and containing 5% to 50% Mo powder
A 153 powder dispersed Ni plating film or a Ni-based alloy plating film is provided.

Mo 5% above 50% 4 M
In the case of ONi plating or Ni-containing plating, in the case of (2) above, it is preferable that the above-mentioned Mo.
This is suitable from the viewpoint of further improving the adhesion of the containing film and obtaining a plating that is less prone to crank formation. This case will be explained below.

First, the reason for using two-layer plating consisting of the Mo powder-dispersed Ni plating film or Ni-based alloy plating film and the Ni plating layer or Ni-based alloy plating layer as a base is as follows.

(2) The effect of the Mo powder-dispersed Ni plating film or the Ni-based alloy plating film on the outermost surface is the same as in the case (2) above. In other words, the particles in this plating film combine preferentially with oxygen in the atmosphere during welding to form an oxide, sufficiently lowering the surface oxygen potential.

■The Nj plating or Ni-based alloy plating provided on the surface of the base high-alloy member is very strongly bonded to the upper layer, the Mo powder-dispersed Ni plating film or the Ni-based alloy plating film. The peeling resistance (adhesion) of a Mo powder-dispersed Ni plating film or a Ni-based alloy plating film is improved.

■Ni plating or Ni-based alloy plating firmly adheres to the base high-alloy component, so the Mo-containing coating obtained by the present invention is difficult to get cranked in and reliably prevents oxidation of the high-alloy component. I can do it.

■Therefore, Mo powder dispersed Ni plating film or Ni
Even if the thickness of the base alloy plating film is less than that in case (■), the surface of the high alloy component has a plating that has good adhesion and is difficult to crack, and can withstand multiple passes of welding. This makes it extremely suitable for preventing deterioration of the corrosion resistance of welded parts during multilayer welding.

Next, the reason why it is preferable to limit the Mo content in the Ni-Mo alloy plating of the surface layer to 5% or more and 50% or less will be explained. If the Mo content is less than 5%, the oxygen potential will not be sufficiently reduced because the amount of oxygen that combines with Mo will not be sufficiently reduced, and even if the underlying Ni plating layer or Ni-based alloy plating layer is thick, the corrosion resistance of the weld scale generation area will deteriorate. This is because there is a risk that deterioration of the
Although it is effective in preventing deterioration of the corrosion resistance of weld scale parts,
This is because if it exceeds this value, alloy plating with good adhesion cannot be obtained.

In other words, it is the same as the case (2) above.

In addition, the thickness of the Ni-Mo alloy plating on the surface layer was set to 0.1-
The reason for the above limitations will be explained. This is because if it is less than 0.1μ, the pores will combine with oxygen and be consumed during repeated welding, leading to unavoidable deterioration of the corrosion resistance of the weld scale generation area.

Desirably, the thickness is 1 μ or more. Further, although there is no need to specify the upper limit, it is desirable that the upper limit is 100 A or less because plating takes a long time and the effect is saturated.

Next, the Ni plating or Ni-based alloy plating that is present between the surface of the base high-alloy member and the surface layer made of the above-mentioned powder-dispersed Ni plating film or Ni-based alloy plating film will be explained. These are similarly plated using Ni as a matrix in order to firmly adhere the powder-dispersed Ni plating film or the Ni-based alloy electroplating film on the surface. Compared to other metal plating methods, Ni plating is simpler and more well-established, and in electroplating, it has good current efficiency and thick plating without cracks can be obtained.

The Ni-based alloy may be any Ni-based alloy that has good adhesion to high-alloy members, specifically N1-
Examples include P alloy, N1-Go alloy, and Ni-Fe alloy. Further, in these alloys, it is preferable that the Ni content is 60% or more from the viewpoint that Ni itself has the effect of suppressing oxidation of the weld heat affected zone. Furthermore, it is also suitable that the Mo content in these alloys is less than 5%. Ni plating layer or N
This is because Mo in the i-based alloy plating layer does not directly contribute to the effect of preventing deterioration of corrosion resistance, but only increases the cost.

The plating thickness of this Ni or Ni-based alloy plating is 1 AIa.
If it is less than 1, the MO in the surface layer will combine with oxygen and be consumed during repeated welding, and when the oxygen potential increases, weld scale will be generated, which will deteriorate the corrosion resistance. This is because deterioration may be unavoidable. There is no need to set an upper limit, but 1o
If it exceeds o/jI, the effect of preventing deterioration of corrosion resistance will increase, but plating will take a long time and the effect will reach saturation, resulting in an increase in cost. Therefore, it is preferably 1004 or less.

Note that this Ni plating layer or Ni-based alloy plating layer as a base can also be applied to the high-alloy members according to the present invention explained in the above-mentioned (1) to (2) to obtain the same effect. In either case, the Ni-based alloy plating layer can be formed by electroplating or electroless plating.

Further, the welding method used for welding the high-alloy members according to the present invention may be any conventionally widely used method, such as arc welding typified by the TiC method. There is no restriction in any way, and the high alloy member according to the present invention may be welded to another member at the portion where the Mo coating or Mo-containing coating is applied.

Furthermore, if the high-alloy component is a pipe, for example, after performing circumferential welding, it is only necessary to remove the scale on the outer surface by grinding with a grinder, etc., and the inner surface of the pipe remains welded. There is no problem in that.

By the way, in the above description of the high alloy member according to the present invention, the MO coating or Mo
The containing film is just an example, and rM in the present invention
It goes without saying that the terms ``O coating'' or ``Mo-containing coating'' are not limited to these embodiments.

In other words, even if the coating is other than the MO coating or Mo-containing coating explained in the above-mentioned to This is because it is clear that it has.

Further, the present invention will be described in detail using Examples, but these are merely illustrative of the present invention, and the present invention is not unduly limited thereby.

Example 1 High alloy tube NaA or NaE having the composition shown in Table 1
(Outer diameter 80 mm, wall thickness 7 mm) The inner surface (range within 501 I from the end of the tube) was treated by the method of the present invention and the conventional method shown in Table 2, and the results shown in Table 3 were Circumferential welding (one-layer welding and four-layer welding) was performed under the welding conditions shown.

In addition, high alloy 't F having the composition also shown in Table 1
4 [LA Su L' shik E (outer diameter 80s + m, thickness W 7 + n1) (7) Apply a plating bath with the composition shown in Table 4 to the inner surface of each groove (within 50 m from the end of the tube). A Ni plating layer of 5 μm was applied as a base using the electroplating method, or a Ni-based alloy (97%Ni-3%P) plating layer was applied as a base using the electroless plating method using a plating bath having the composition shown in Table 5, and then After performing the treatments according to the present invention method and the conventional method shown in Table 2, circumferential welding (11-layer welding and 4-layer welding) was performed under the welding conditions shown in Table 3.

Table 2 Table 3 Table 4 Table 5 Then, a sample with a width of 10 mm, a thickness of 3III, and a length of 40 m was cut out from the inner surface layer of the circumferential weld, with the center of the weld metal as one end, and the weld heat affected zone was cut out. The pitting potential was measured.

The pitting potential is 60'C110'pps+a! -(NaC
Qi solution), the potential of the test piece was raised under the conditions of 0.05 V/day to a potential at which pitting corrosion occurred. For comparison, a sample was also cut out from the base metal that was not affected by welding heat, and the pitting potential was measured in the same way.

The results are summarized in Table 6.

(Left below) As is clear from the pitting potential measurement results shown in Table 6,
In the sample obtained by processing method Nci3 (Cr powder application),
In particular, it can be seen that when four-layer welding is performed, the pitting corrosion potential decreases and the pitting corrosion resistance significantly deteriorates. On the other hand, samples obtained by the processing method (HMo powder application) according to the present invention can be used in 11-layer welding and 4-layer welding, regardless of the presence or absence of the Ni plating layer or Ni-based alloy plating layer as the base. The scale formation prevention effect remained unchanged, and the pitting potential value was comparable to that of the base material, indicating that the corrosion resistance had not deteriorated.

Furthermore, for the samples according to the present invention, the adhesion of the plating layer was examined using a tape test method, which is a type of peel test method, in which adhesive tape is attached and then peeled off to check for film peeling. However, no peeling of the film occurred at all, and the adhesion was excellent in both cases.

That is, it can be seen that, according to the present invention, a sufficient scale generation prevention effect could be provided even in multi-layer welding, for example, butt welding of high alloy pipes.

Example 2 5 questions consisting of 100 questions in width, 200 questions in length, and 31 in thickness.
US316L, 5US329J2L (25% Cr duplex stainless steel) and high Ni alloy A11oy
The plating material was made by polishing a No. 825 plate with No. 600 emery paper.

Then, direct Mo molten salt plating was performed on this plating material under any of the four bath composition conditions shown in Table 7, which have been tried in the past, to obtain samples N[Ll to 10. The film thickness was adjusted by changing the electrolysis time and current density. The plating film thickness was measured by cross-sectional microscopic observation.

Further, a Ni plating layer or a Ni-based gold plating (97% Ni-3% P alloy) N was added to the plated material as a base under the conditions shown in Table 4 or Table 5 as in Example 1.
After μ plating, old molten salt plating was applied as an upper layer under the same conditions as described above to obtain samples Nα11 to Nα15.

Table 7 After performing Mo molten salt plating in this way, 0.
TI in an Ar gas shield atmosphere containing 1% by volume of 0□
For G tanning, heat input is 1 for welding (TIGf8 welding without filler)
0 J/cm, and 7N fill welding was performed under the welding conditions shown in Table 8. After that, 20 x 40 x 3 (
A test piece of the nut was cut out and subjected to a corrosion test. Lead wires were soldered to these test pieces before the test, the connection parts were coated with silicone resin, and the test pieces were used for electrochemical measurements.

Table 8 Corrosion resistance evaluation was carried out in the environment shown below.
The potential was moved to the front side every 4 hours, and the potential at which pitting corrosion occurred in the weld scale portion was defined as the pitting corrosion potential.

(Environment), i) 10'ppa+Cl2-
(NaCi2 solution) ii) 60°C iii) Open to atmosphere The results are shown in Table 9.

Table 9 (Continued on next page) (Continued from Table 9) (Note) Umbrellas are outside the scope of the present invention As is clear from Table 9, the pitting corrosion resistance is improved by the present invention.

Moreover, by comparing Samples N[11 to 15 with Sample No. 18 and Sample No. 4Na23, it can be seen that the present invention can further improve corrosion resistance than the conventional method of removing welding scale after welding. .

Furthermore, samples 1t19 to 21 are
These samples were obtained by the method disclosed in Japanese Patent No. 38287, and were welded with a coating mainly composed of Q, Si, and Mn applied to the portion corresponding to the heat affected zone before welding. The pitting corrosion potential of Samples 19 to 21 after TIG lick welding was about 0.20 to 0.25, and Samples 1! 116, sample N
JP 63-23828 than ct17 and sample 22
It can be seen that the means disclosed in Publication No. 7 is superior. However, sample N11l to sample Nα15 according to the present invention
The pitting corrosion potential of the samples was even better than that of samples Nu29 to N1121, and there was almost no deterioration even when multi-layer welding was performed, which clearly demonstrates the effects of the present invention.

The effect of improving the corrosion resistance of the weld scale-generated portion of the sample according to the present invention is regardless of the presence or absence of the Ni or Ni-based alloy plating layer as the base, and in particular, the corrosion resistance is excellent regardless of the presence or absence of the Ni or Ni-based alloy plating layer as the base. The adhesion of the sample having the Ni or Ni-based alloy plating layer was excellent and suitable as no peeling occurred in the same tape test method as described above.

Example 3 5IIS316L, 5IJS329J2L with dimensions of 100 mm in width, 200 questions in length, and 3 m and 11 m in thickness.
(25% Cr-based duplex stainless steel) and Al1oy 825 plate, which is a high Ni alloy, was coated with emery paper N11600.
Polished using a polishing machine. After this, (i) Ni plating layer or Ni-based alloy (97%N+-3%P alloy) plating as a base under the conditions shown in Table 4 or Table 5 as in Example 1 and Example 2. 5μ layer
The plated materials were used as plating materials, or (ii) as-polished materials.

The operations shown in (1) and (2) below were performed on these two types of plating materials.

■As a pretreatment for plating, degreasing and pickling (however, the above (i)
For the plated materials listed above, pickling was omitted to protect the underlying plating), and then electroplating was performed under the conditions shown in Table 10.

The plating bath in Table 10 was prepared using ion-exchanged water and a commercially available special grade reagent. The electrolytic chamber was separated into a cathode chamber and an anode chamber using a diaphragm. The composition and film thickness of Fe/Mo, Fe/Ni/Mo were adjusted by bath composition and electrolysis time.
The layer thickness was measured by cross-sectional microscopic observation, and
o concentration was determined by EPMA analysis.

(2) The pretreatment for plating was a two-component activation treatment specified in JI388617-1977, which included immersion in a 5na2z solution and a PdCQz solution. Mote Ni
-Mo alloy electroless plating was performed under the conditions shown in Table 11, and the film thickness and Mo content were determined by the immersion time and NaJoOa
Adjustment was made by changing the fA degree. The film thickness was measured by cross-sectional microscopic observation.

Table 11: The size of the plated surface is radius 20+u+, length 2ooII
Ill, plating was performed by masking the plated surface with tape. After plating, the masking was removed and 0.1% by volume of 0. Including A "TIG tanning is welding in a gas shielded atmosphere (TIG without filler)
t4 contact) was carried out while controlling the heat input to 10 KJ/cm,
In addition, 7-layer build-up welding was carried out under the same welding conditions shown in Table 8 as in Example 2, and then, similarly to Example 2, 20 x 4
A test piece of 0 x 3 (ms) was cut out and subjected to a corrosion test. Before testing, these specimens were soldered with lead wires and the connections were coated with silicone resin.
Used for electrochemical measurements.

Corrosion resistance evaluation was performed in the environment shown below at 50 mV each.
The potential was moved to the front side every 4 hours, and the potential at which pitting corrosion occurred in the weld scale portion was defined as the pitting corrosion potential.

(Environment) i) 10'ppIICQ-(Na
C12 solution) ii) 60° C. iii) Table 12 shows the results of the sample obtained by operation (2) under open atmosphere, and Table 13 shows the results of the sample obtained by operation (2).

Table 2 (Continued from Table 1z) (il:) is the scope of the present invention (Table 3 (Continued on the next page) (Continued from Table 13) (in) Umbrellas are clearly outside the scope of the present invention from Table 12 According to the present invention, Fe-
Samples (sample N [ll to sample 19) cut out from the welded part of a high alloy member in which Mo alloy plating or Pe-Ni-Mo alloy electroplating was applied to the area corresponding to the heat-affected zone during welding. The pitting corrosion potential is 0.25 V vs SCE or more after TIG lick welding, and 0.20 V vs SCE or more after 7-layer welding, and no deterioration of the corrosion resistance of the welds is observed.

On the other hand, the pitting potential of the comparative samples (Samples N1120 to Nn25) was 0.2 V vs SCE or less after TIG lick welding, and 0.2 V vs SCE after 7-layer welding.
It can be seen that the corrosion resistance of the weld heat affected zone is significantly deteriorated.

Also, from Table 13, Ni-N according to the present invention.

It is clear that the pitting corrosion resistance of the sample in which alloy plating was applied to the area corresponding to the heat-affected zone during welding is improved.

Moreover, by comparing the sample holes 26 to 57 with the sample holes 60, it can be seen that the present invention can further improve corrosion resistance than the conventional method of removing weld scale after welding.

Furthermore, samples tb61 to sample Nα63 are
These samples were obtained by the method disclosed in Japanese Patent No. 238287, and were welded by coating the heat-affected zone with a coating mainly composed of AQ, Si, and Mn before welding. Sample N
The pitting potential of 1161 to sample part 63 is approximately 0.20 to 0 after welding for TIG tanning, and 0 after layer welding of 25.7.
．． 20 to about 0.15, indicating that the method disclosed in JP-A-63238287 is superior to sample N1158 and sample portion 59, which were not subjected to the welding scale removal method. However, sample Nα26 according to the present invention
The pitting potential of sample #J-57 was even better than that of sample portion 61 to sample Na63, and the effect of the present invention is clear.

Example 4 SUS316L steel, 5IIS329J2L (25%C
r2 phase stainless steel! 1) and high Ni alloy A11oy
825 seamless tube with an outer diameter of 80 mm and a wall thickness of 71 mm, each cut into lengths of 100 AU+, and the inner and outer surfaces degreased and pickled are used as plating materials.1! The outer surface of the tube was masked with tape, and MO powder dispersion plating was applied only to the inner surface under various conditions shown in Table 14.

After plating, remove the tape and apply the same conditions as in Example 2 (
(See Table 8) Welded the outer surface and inner circumference. At this time, it was decided to compare the corrosion resistance of the welded parts after one-layer welding and after seven-layer welding.

Corrosion resistance was evaluated by taking a test piece with a width of 10 mm, a thickness of 3 mm, and a length of 40+ seconds from the inner layer of the outer circumferential weld, with the center of the weld metal as one end, and measuring the pitting corrosion potential of the weld.

The pitting corrosion potential was the same as in Examples 1 to 3, 60°C1
During 10'ppIsCQ-CNaCQ welding), the potential of the test piece was increased stepwise under conditions of approximately 0.05 V/day, and the potential at which pitting corrosion occurred in the weld was defined as the pitting corrosion potential. In addition, for comparison, test pieces were also taken from base metal parts that were not affected by heat during welding, and the pitting corrosion potential was similarly measured.

Note that the Nj plating layer or Ni-based alloy (9
The plating layer (7% Ni-3% P) was formed using a plating bath having the same composition as used in Examples 1 to 3 (see Tables 4 and 5).

In addition, using a plating bath (see Tables 4 and 5) having the same composition as that used to obtain the Mol powder dispersed mebumetsu, the base Ni plating layer or the Ni-based alloy plating layer described below, the average 3-30g/l of MO powder with a particle size of 3μ
In the case of the plating bath shown in Table 4, electroplating was carried out, and in the case of the plating bath shown in Table 5, electroless plating was carried out.

Further, the thickness of the base plating layer, the thickness of the Mo15) undispersed plating layer, and the MO powder content were adjusted by changing the treatment time and/or 'gX and flow density. The thickness of each film was measured by cross-sectional microscopic observation.

The results are summarized in Table 14.

As shown in Table 14, when the Mo powder content and film thickness are within the desired range of the present invention, the scale generation prevention effect remains almost unchanged even after 7-layer welding, and is almost equivalent to the base metal. It shows corrosion resistance, and it can be seen that the deterioration in corrosion resistance is extremely small even during multilayer welding. Furthermore, even if the Mo powder content and film thickness are out of the desirable range of the present invention, the method disclosed in JP-A-63238287 can be used (Samples N1119 to 21 in Table 9 and Sample No. 61 in Table 13). (See Nct63)
It can be seen that the corrosion resistance is equivalent to or higher than that of . Furthermore, Ni
or/and the 13th layer plating of Ni7J alloy
As is clear from the comparison with sample level 64 to sample level 68 in the table, if Mo powder is not dispersed in the upper plated layer, deterioration of corrosion resistance cannot be prevented even if the plated layer is thickened, whereas this It can be seen that the invention can prevent deterioration of corrosion resistance.

(Effects of the Invention) As described above, the present invention has established a measure to prevent deterioration of corrosion resistance due to scale formation in welded parts, and in particular, it has become possible to ensure and complete corrosion protection of the inner surface of the outer circumferential welded part of piping, which had been a problem until now. , welding problems caused by on-site welding work have been resolved.

Furthermore, if these platings are applied to high-alloy materials such as stainless steel materials, the corrosion resistance of weld scale parts will of course be improved. The effect is that corrosion resistance does not deteriorate even after external circumferential welding, which requires several passes.

The significance of the present invention having such effects is extremely significant.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram showing a plating site, a welding site, and a test piece in an example of the present invention.

Claims (8)

[Claims] (1) At least in the area corresponding to the heat affected zone during welding,
A high alloy member characterized by having a Mo coating or a Mo-containing coating. (2) The high alloy material according to claim 1, wherein the Mo coating is a Mo powder coated coating applied to the surface of the high alloy member directly or via a Ni plating layer or a Ni-based alloy plating layer as a base. Alloy-based parts. (3) The Mo coating is a Mo molten salt with a thickness of 0.1 μm or more applied to the surface of the high alloy member directly or via a Ni plating layer or an N1-based alloy plating layer as a base. The high alloy member according to claim 1, which is a plated film. (4) The Mo-containing coating may be applied directly to the surface of the high-alloy member, or to a Ni plating layer or a Ni plating layer as a base.
Ni-Mo alloy, Fe-Mo alloy, or Fe-Ni- alloy having a thickness of 0.1 μm or more and containing 5% by weight or more and 40% by weight or less of Mo, which is applied through a base alloy plating layer.
The high alloy member according to claim 1, which is a plating film of Mo alloy. (5) The Mo-containing coating is applied directly to the surface of the high alloy member, has a thickness of 1 μm or more, and contains Mo powder dispersion N containing 5% by weight or more and 50% by weight or less of Mo powder.
The high alloy member according to claim 1, which is an i-plated coating or a Ni-based alloy plated coating. (6) The Mo-containing coating has a thickness of 0.1 μm or more and is applied to the surface of the high-alloy member through a Ni plating layer or a Ni-based alloy plating layer as a base,
The high alloy member according to claim 1, which is a Mo powder-dispersed Ni plating film or a Ni-based alloy plating film containing 5% by weight or more and 50% by weight or less of powder. (7) The high alloy member according to any one of claims 2 to 4 or 6, wherein the Ni plating layer or Ni-based alloy plating layer as the base has a thickness of 1 μm or more. (8) A high alloy member according to any one of claims 1 to 7, wherein the high alloy member is welded to another member at a portion where the Mo coating or Mo-containing coating is applied. welding method.