JP2014152379A - Etching method, evaluation method for metallographic structure including execution of the etching method and etching solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable sufficient etching of the surface of an object even when the angle of the surface of the object to the upward horizontal surface is large and facilitate work in e.g. an etching application step.SOLUTION: An etching method includes an etching solution formation step of forming an etching solution 20 by mixing an acetic acid alcohol 21 serving as a metal corrosion liquid with glycerol 22 and an etching solution application step of applying the etching solution 20 to the surface 11 of an object 10.

Description

  The present invention relates to an etching method for etching a surface of an object formed of a metal, a metal structure evaluation method for executing the method, and an etching solution.

  As a method for nondestructive inspection of the metal structure of an object formed of metal, there is a method described in Patent Document 1 below.

  In this method, first, after polishing the surface of the object, the surface is etched. In this etching, a metal corrosive solution such as a nitrate alcohol solution is applied to the surface of an object, and the metal on the surface is corroded with the metal corrosive solution. Next, the surface is cleaned with a cleaning solution.

  Next, when the etching of the surface of the object is completed, a film is attached to the etched surface, and fine irregularities on the etched surface are transferred to the film. That is, a replica of the etched surface is collected. Then, this film is observed with a microscope or the like.

JP-A 64-91034

  However, in the technique described in Patent Document 1, when the surface of the object spreads in the vertical direction, for example, the metal corrosive liquid does not stay in the target area in the surface of the object but immediately flows down. The surface of the film may not be etched sufficiently. Furthermore, if the portion where the metal corrosive liquid has flowed is a narrow portion of the object, the metal corrosive liquid accumulated in the narrow portion may not be washed.

  In addition, when the surface of the object is downward and spreads in a substantially horizontal direction, the metal corrosive liquid dripping immediately immediately, and not only the surface of the object cannot be etched sufficiently, but also the operator may fall.

  That is, in the prior art, when the angle of the surface of the object becomes large with respect to the upward horizontal plane, not only the surface of the object cannot be etched sufficiently, but the work in the post-etching process such as the etching construction process and the cleaning process can be performed. There is a problem that it is extremely troublesome.

  Therefore, the present invention can sufficiently etch the surface of the object even when the angle of the surface of the object is large with respect to the upward horizontal plane, and can easily perform the work in the etching construction process and the post-etching process. It is an object of the present invention to provide an etching method, a method for evaluating a metal structure that executes this method, and an etching solution.

The etching method as one aspect according to the invention for solving the above problems is as follows:
In an etching method for etching a surface of an object formed of metal, an etching solution generating step of generating an etching solution by mixing glycerin with a metal corrosive solution for the metal, and the etching solution is used for the surface of the object And performing an etching solution construction process applied to the substrate.

  In the etching method, the viscosity of the etching solution can be increased by mixing glycerin. For this reason, in the etching method, even if the angle of the surface of the object with respect to the upward horizontal plane is large, the etching solution can be kept in the target region in the surface of the object. Therefore, according to the etching method, the surface of the object can be sufficiently etched, and the cleaning range of the object can be narrowed.

  In addition, in this etching method, even when the surface of the object is downward and spreads in a substantially horizontal direction, the etching solution does not drip immediately below, so that the surface of the object can be sufficiently etched and the work can be performed. The possibility of this etching solution falling on the person can be extremely reduced.

  Here, in the etching method, in the etching solution generation step, as the metal corrosive liquid, a nitric acid alcohol liquid, a ferric chloride solution, a picric acid alcohol liquid, or the like is selected from these liquids according to a target member. Select the appropriate working solution.

  Further, in any one of the above etching methods, in the etching solution generation step, the concentration of the glycerin in the etching solution is set such that the angle of the surface is small with respect to an upward horizontal plane. The glycerin concentration when the surface angle is larger than the glycerin concentration may be increased.

  In this etching method, even if the angle of the surface with respect to the upward horizontal plane increases, the glycerin concentration is increased and the viscosity of the etching solution is increased accordingly. Can stay within the destination area.

  Further, in any one of the above etching methods, in the etching solution generation step, when the etching solution is dropped on the surface of the object, the concentration of the glycerin in the etching solution is reduced. The etching solution residence time staying in a predetermined region is set to a concentration that is equal to or longer than the required etching time until the surface is etched by a predetermined amount after the etching solution is applied to the surface of the object. Also good.

  In this etching method, even if an etching solution is applied to the surface of an object that is inclined with respect to the upward horizontal plane, the etching solution stays around the region where the etching solution has been applied for more than the etching time required for this etching solution. it can. Therefore, in the etching method, even if an etching solution is applied to the surface of the object that is inclined with respect to the upward horizontal plane, the surface of the object can be reliably etched by a predetermined amount.

  In any one of the above etching methods, in the etching solution generating step, the surface is etched by a predetermined amount after the concentration of the glycerin in the etching solution is applied to the surface of the object. The concentration may be such that the time required for etching until the etching is performed is equal to or less than a predetermined time.

  In this etching method, the etching required time is equal to or shorter than a predetermined time, so that the efficiency of the etching operation can be improved.

  Further, in any one of the above etching methods, the etching solution application step is performed for a time required for etching until the surface is etched by a predetermined amount after the etching solution is applied to the surface of the object. After the elapse of time, a cleaning process for cleaning the surface of the object may be executed.

  In this etching method, the surface of the object is cleaned after the etching solution construction process has been executed and the etching solution used for the etching solution construction process has passed the required etching time. For this reason, in this etching method, the etching solution is not washed before the time required for etching elapses, and the surface of the object can be reliably etched by a predetermined amount.

  In any of the above etching methods, in the etching solution application step, the impregnating member may be impregnated with the etching solution, and the impregnating member may be brought into contact with the surface of the object. In any of the above etching methods, in the etching solution application step, the etching solution may be applied to a sheet, and the sheet may be attached to the surface of the object.

  In the etching method using the impregnated member or sheet, the etching solution is difficult to diffuse from the impregnated member brought into contact with the surface of the object (including when pasted) or the sheet attached to the front of the object. The time required for etching can be shortened by reducing the concentration. As a result, in the etching method, the waiting time until the surface of the object is cleaned after the etching solution is applied to the surface of the object can be shortened.

  In the etching method using an impregnated member or a sheet, the angle of the surface with respect to an upward horizontal plane may be 90 ° or more.

  In the etching method using an impregnated member or sheet, the surface angle is 90 ° or more with respect to the upward horizontal surface, and the metal corrosive liquid applied to the surface may immediately flow down, or the metal corrosive liquid may drip immediately below. Even if there is a property, the etching solution is difficult to diffuse as described above. For this reason, the etching method using an impregnated member or a sheet is extremely effective when the etching solution is applied at an angle of 90 ° or more with respect to an upward horizontal plane.

  In any of the above etching methods, the etching solution may be applied in the etching solution application step.

The metal structure evaluation method as one aspect according to the invention for solving the above problems is as follows.
An etching process for etching the surface of the object by any one of the etching methods described above, a replica collecting process for transferring the tissue shape of the surface etched in the etching process to a film, and a tissue shape of the surface transferred An evaluation step of observing the film and evaluating a metal structure forming the object.

The etching solution as one aspect according to the invention for solving the above problems is
A metal corrosive solution and glycerin are mixed.

  Since the etching solution has a higher viscosity, the etching solution can remain in the target region in the surface of the object even when the angle of the surface of the object with respect to the upward horizontal surface is large. Therefore, according to the etching solution, the surface of the object can be sufficiently etched and the cleaning range of the object can be narrowed.

  In addition, with the etching solution, even when the surface of the object is downward and spreads in a substantially horizontal direction, the etching solution does not drip immediately below, so that the surface of the object can be sufficiently etched and The possibility of this etching solution falling on the person can be extremely reduced.

  Here, in the etching solution, the metal corrosion solution is a nitrate alcohol solution, a ferric chloride solution, a picric acid alcohol solution, or the like, and a use solution is appropriately selected from these solutions according to the target member. .

  In the present invention, even if the angle of the surface of the object is large with respect to the upward horizontal plane, the surface of the object can be sufficiently etched, and the work in the etching process and the post-etching process can be facilitated.

It is explanatory drawing explaining the procedure of the evaluation method of the metallographic structure in one Embodiment which concerns on this invention. It is a graph which shows the characteristic according to the glycerol density | concentration of the etching solution in one Embodiment which concerns on this invention. The graph which shows the characteristic change accompanying the glycerin density | concentration change of the etching solution in one Embodiment which concerns on this invention, and shows the characteristic of the etching solution in case the angle of the surface of the target object with respect to an upward horizontal surface is larger than the case of FIG. It is. It is explanatory drawing which shows the relationship between the glycerol density | concentration of the etching solution in one Embodiment which concerns on this invention, and the angle of the surface of the target object with respect to an upward horizontal surface. It is explanatory drawing which shows the effect | action content in the etching solution construction process in the 1st modification of one Embodiment which concerns on this invention. It is explanatory drawing which shows the effect | action content in the etching solution construction process in the 2nd modification of one Embodiment which concerns on this invention.

  Hereinafter, an embodiment and a modification of a metal structure evaluation method according to the present invention will be described with reference to the drawings.

"Embodiment"
First, with reference to FIGS. 1-4, one Embodiment of the evaluation method of the metal structure which concerns on this invention is described.

  In the present embodiment, the metal structure of an object formed of a metal such as carbon steel used in a plant or the like is evaluated. In the following, a pipe formed of carbon steel will be described as an example of an object. However, the object in the present invention is not limited to a pipe, and for example, other objects formed of other metals such as a turbine casing. It may be a member. Further, the material of the object in the present invention is not limited to carbon steel, and may be stainless steel, for example.

  In this embodiment, as shown to Fig.1 (a), the etching solution for etching the surface 11 of the target object 10 is produced | generated first (etching solution production | generation process). Here, glycerin 22 is mixed with nitrate alcohol 21, which is a kind of metal corrosive liquid, so-called nital, and this is used as an etching solution. The glycerin concentration in the etching solution will be described later.

  Next, as shown in FIG.1 (b), the surface 11 of the target object 10 is grind | polished (surface grinding | polishing process). In this surface polishing step, for example, a sandpaper, a felt buff 31 or the like is attached to a tool 32 such as an electric router or a hand drill, and the surface 11 of the object 10 is polished. Moreover, it grind | polishes using a diamond abrasive grain etc. as needed.

  Next, as shown in FIG.1 (c), the etching solution 20 produced | generated at the above-mentioned etching solution production | generation process is applied to the surface 11 of the target object 10 (etching solution construction process). In this etching solution construction process, the etching solution 20 contained in the nozzle-equipped bottle 35 is sprayed from the nozzle 36 to the evaluation region 12 in the surface 11 of the object 10. At this time, the absorbent cotton 39 is picked by the tweezers 38, and the etching solution 20 sprayed on a part of the evaluation region 12 is spread over the entire evaluation region 12 by the absorbent cotton 39. When the etching solution application process is completed, the process waits for an etching time required for etching a predetermined amount of the evaluation region 12 in the surface 11 of the object 10. During the time required for this etching, the absorbent cotton 39 containing the etching solution 20 may be pressed against the evaluation region 12 or the like. After the etching solution construction process is completed, if the time required for etching elapses, the evaluation region 12 and its periphery are cleaned with alcohol or the like (cleaning process).

  As described above, a series of steps from the etching solution generation step to the cleaning step forms the etching step in the present embodiment. In the above, the surface polishing process is performed after the etching solution generation process is performed. However, since the etching solution generation process only needs to be performed before the etching solution construction process, the surface polishing process is performed. Then, the etching solution generation step may be performed.

  Next, as shown in FIG.1 (d), the replica of the fine unevenness | corrugation in the evaluation area | region 12 in the surface 11 of the target object 10 is extract | collected (replica acquisition process). In this replica collecting step, a methyl acetate solution 29 is applied to the evaluation region 12 in the surface 11 of the object 10, and a film 40 formed of acetylcellulose or the like is pressed on the evaluation region 12, and the tissue shape of the evaluation region 12 is changed. Transfer to film 40. Note that the methyl acetate solution has a role of dissolving acetyl cellulose forming the film 40.

  Finally, the film 40 to which the tissue shape of the evaluation region 12 is transferred, that is, the replica 41 is observed with a microscope to evaluate the metal structure of the object 10 (metal structure evaluation step). In this evaluation step, for example, voids recognized in the metal structure transferred to the film 40 are observed, and the degree of creep damage is evaluated by the A parameter method. Note that another method may be used as a method for evaluating the metal structure. For example, a method disclosed in Japanese Patent No. 3886935 may be used. This method is a method of observing the presence or absence of voids and precipitates, and their distribution, and evaluating the lifetime consumption of the object by comparing this observation result with a standard structure in several stages according to the lifetime consumption. .

  Thus, the metal structure evaluation is completed.

  Next, the glycerin concentration in the etching solution will be described with reference to FIGS. 2 and 3 are both graphs showing the characteristics of the etching solution according to the glycerin concentration, and FIG. 3 shows a case where the angle of the surface of the object relative to the upward horizontal plane is larger than that in FIG. The characteristics of the etching solution are shown.

  When the etching solution is dropped on the surface of the object inclined with respect to the upward horizontal plane, as shown in FIGS. 2 and 3, the viscosity of the etching solution increases as the glycerin concentration increases. The etching solution residence time Ts in which the etching solution stays in a predetermined region is gradually increased. In addition, as the glycerin concentration of the etching solution increases, the required etching time Tr for etching the surface of the object by a predetermined amount gradually increases, and when the concentration exceeds a certain concentration, the required etching time Tr increases abruptly.

  Therefore, in this embodiment, the concentration of glycerin in the etching solution is set within a concentration range C1 in which the etching solution residence time Ts is equal to or longer than the required etching time Tr. As a result, even if the etching solution is applied to the surface of the object inclined with respect to the upward horizontal plane, the etching solution is reliably retained around the region where the etching solution has been applied for the etching required time Tr or longer. I can keep it. Therefore, in the present embodiment, even if the etching solution is applied to the surface of the object that is inclined with respect to the upward horizontal plane, the surface of the object can be reliably etched by a predetermined amount. However, if the etching required time Tr becomes too long, workability deteriorates. Therefore, the concentration of glycerin in the etching solution is set within a concentration range C2 where the etching required time Tr is equal to or less than a predetermined time T. Is preferred.

  By the way, as described above, the time required for etching Tr varies depending on the glycerin concentration in the etching solution. For this reason, it is necessary to set the waiting time until the surface of the object is cleaned after the etching solution is applied to the surface of the object to be equal to or longer than the required time Tr corresponding to the glycerin concentration in the used etching solution. Therefore, in the present embodiment, as described above, after the etching solution is applied to the surface of the object, the surface of the object is cleaned after the etching time Tr of the etching solution has elapsed.

  As can be understood from a comparison between FIG. 2 and FIG. 3, the etching solution residence time Ts becomes shorter as the angle of the surface of the object with respect to the upward horizontal plane is larger even if the glycerin concentration is the same. On the other hand, if the glycerin concentration is the same, the required etching time Tr does not change even if the angle of the surface of the object with respect to the upward horizontal plane changes.

  For this reason, the minimum concentration in the concentration range C1 in which the etching solution residence time Ts is equal to or longer than the required etching time Tr increases as the angle of the surface of the object with respect to the upward horizontal plane increases. For this reason, as shown in FIG. 4, as the angle α of the surface 11 of the object 10 with respect to the upward horizontal plane increases, the glycerin concentration in the etching solution is increased. It is preferable to increase the amount. However, if the angle α of the surface 11 of the object 10 with respect to the upward horizontal plane is 90 ° or more, the etching solution residence time Ts does not increase even if the glycerin concentration is increased. As shown in e), when the angle α of the surface 11 of the object 10 with respect to the upward horizontal plane is larger than 90 °, the glycerin concentration does not need to be higher than the glycerin concentration when the angle α is 90 °. Further, as shown in FIG. 4A, when the angle α of the surface 11 of the object 10 with respect to the upward horizontal plane is 0 °, that is, when the surface 11 of the object 10 is the upward horizontal plane, metal corrosion is caused. The liquid 21 may be mixed with glycerin 22 but the metal corrosion liquid 21 that is not mixed with glycerin 22 may be used as the etching solution.

  As described above, in this embodiment, the viscosity of the etching solution is increased by mixing glycerin with the metal corrosive liquid. For this reason, in this embodiment, even if the angle of the surface of the object with respect to the upward horizontal plane is large, the etching solution can be kept in the target region in the surface of the object, and the surface of the object can be etched sufficiently. Moreover, the cleaning range of the object can be narrowed.

  Further, in the present embodiment, even when the surface of the object is downward and spreads in a substantially horizontal direction, the etching solution does not drip immediately below, so that the surface of the object can be sufficiently etched and the work can be performed. The possibility of this etching solution falling on the person can be extremely reduced.

  Therefore, in this embodiment, even if the angle of the surface of the object is large with respect to the upward horizontal plane, the surface of the object can be sufficiently etched, and the etching solution application process and the cleaning process can be easily performed. it can.

"Modification of etching solution construction process"
Next, with reference to FIG.5 and FIG.6, the modification of the etching solution construction process in the said embodiment is demonstrated.

  In the etching solution application process in the embodiment, the etching solution 20 contained in the nozzle-equipped bottle 35 is sprayed from the nozzle 36 to the evaluation region 12 in the surface 11 of the object 10. Further, if necessary, the absorbent cotton 39 is picked by the tweezers 38, and the etching solution 20 sprayed on a part of the evaluation region 12 by the absorbent cotton 39 is spread over the entire evaluation region 12.

  However, in the etching solution application step, as shown in FIG. 5, the etching solution 20 may be immersed in the brush 45 and the etching solution 20 may be applied to the surface 11 of the object 10 using the brush 45. .

  Further, in the etching solution construction process, as shown in FIG. 6, the etching solution 20 may be impregnated in an impregnated member 46 such as gauze or cloth, and the impregnated member 46 may be attached to the surface 11 of the object 10. . In addition, an etching solution is generally applied to the surface of a sheet such as paper that is not an impregnated member, and this sheet is attached to the surface 11 of the object 10 or an etching solution is applied to the surface 11 of the object 10. , You may stick a sheet there. As described above, when the etching solution construction process is performed using the impregnated member 46 or the sheet, the etching solution 20 is less likely to diffuse from the impregnated member or the sheet attached to the surface 11 of the object 10. Thus, the time required for etching Tr can be shortened. As a result, the waiting time from when the etching solution 20 is applied to the surface 11 of the object 10 until the surface 11 of the object 10 is cleaned can be shortened.

  In addition to a glycerin, agar, gelatin, etc. can be considered as what is mixed with a metal corrosive liquid in order to raise the viscosity of an etching solution. However, agar, gelatin and the like react with this metal corrosive liquid and its viscosity is remarkably lowered, so that they are not suitable for mixing with the metal corrosive liquid.

  In the above description, the nitric acid alcohol solution is used as the metal corrosion solution. However, the present invention is not limited to this, and for example, a ferric chloride solution or a picric acid alcohol solution may be used. Thus, even when a ferric chloride solution or a picric acid alcohol solution is used as the metal corrosive solution, it is preferable that the material mixed with the metal corrosive solution is glycerin.

  10: object, 11: surface, 12: evaluation region, 20: etching solution, 21: metal corrosive solution (nitric alcohol), 22: glycerin, 31: sandpaper, felt buff, etc., 35: bottle, 36: nozzle, 38 : Tweezers, 39: Absorbent cotton, 40: Film, 41: Replica, 45: Brush, 46: Impregnated member

Claims (13)

In an etching method for etching the surface of an object formed of metal,
An etching solution generating step of generating an etching solution by mixing glycerin with a metal corrosive solution for the metal;
An etching solution construction step of applying the etching solution to the surface of the object;
Etching method characterized by performing. The etching method according to claim 1,
In the etching solution generation step, a corrosive liquid such as a nitric acid alcohol liquid, a ferric chloride solution, a picric acid alcohol liquid is used as the metal corrosive liquid.
An etching method characterized by the above. The etching method according to claim 1 or 2,
In the etching solution generation step, the concentration of the glycerin in the etching solution is larger than the concentration of the glycerin in the etching solution when the surface angle is small with respect to an upward horizontal surface. Increase the glycerin concentration in the case,
An etching method characterized by the above. In the etching method according to any one of claims 1 to 3,
In the etching solution generation step, when the etching solution is dropped on the surface of the object, the etching solution stays in a predetermined region when the concentration of the glycerin in the etching solution is dropped. The solution residence time is set to a concentration that is not less than the time required for etching until the surface is etched by a predetermined amount after the etching solution is applied to the surface of the object.
An etching method characterized by the above. In the etching method according to any one of claims 1 to 4,
In the etching solution generation step, the time required for etching from when the etching solution is applied to the surface of the target object until the surface is etched by a predetermined amount is determined in advance, based on the concentration of the glycerin in the etching solution. Make the concentration less than the time,
An etching method characterized by the above. In the etching method according to any one of claims 1 to 5,
The surface of the object is washed after the etching solution application process has been performed for a time longer than the time required for etching until the surface is etched by a predetermined amount after the etching solution is applied to the surface of the object. Perform the cleaning process
An etching method characterized by the above. In the etching method according to any one of claims 1 to 6,
In the etching solution construction step, the impregnated member is impregnated with the etching solution, and the impregnated member is brought into contact with the surface of the object.
An etching method characterized by the above. In the etching method according to any one of claims 1 to 6,
In the etching solution construction step, the etching solution is applied to a sheet, and the sheet is attached to the surface of the object.
An etching method characterized by the above. In the etching method according to claim 7 or 8,
The angle of the surface with respect to an upward horizontal plane is 90 ° or more,
An etching method characterized by the above. In the etching method according to any one of claims 1 to 6,
In the etching solution construction step, the etching solution is applied,
An etching method characterized by the above. An etching step of etching the surface of the object by the etching method according to any one of claims 1 to 10,
A replica collecting step of transferring the texture of the surface etched in the etching step to a film;
An evaluation step of observing the film to which the tissue structure of the surface is transferred and evaluating a metal structure forming the object;
A method for evaluating a metal structure, characterized in that: Metal corrosion liquid and glycerin are mixed,
An etching solution characterized by that. The etching solution according to claim 12,
As the metal corrosive solution, use a corrosive solution such as a nitrate alcohol solution, a ferric chloride solution, a picric acid alcohol solution,
An etching solution characterized by that.

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