JP2005350760A - Method for removing burning of stainless steel welded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the various faults accompanying an electrolytic burning removal treatment by the conventional immersion system, i.e., the faults, such as the need for a power source device of an extremely large capacity as compared with the size of the welding burning to be treated, and the occurrence of the unevenness in finishing of the welding burning. <P>SOLUTION: The method for removing the burning of the stainless steel welded product comprises immersing the product to be treated into an electrolyte within a vessel for housing the product to be treated at the time of removing the welding burning of the welded product of the stainless steel by an electrolytic system, and connecting an anode of a DC power source or one end of an AC power source to the product to be treated, then connecting the other one electrode of the power source of any among the power sources described above to a counter electrode composed of a stainless steel product coated with an organic or inorganic woven fabric or nonwoven fabric as an electric short-circuit prevention material and energizing the stainless steel product, and inducing an electrolysis effect between both while successively moving the counter electrode along a weld line of the product to be treated, thereby removing the welding burning. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a novel welding burn removal method for dissolving and removing a weld burn of a stainless steel welded product by an immersion electrolysis method.

In light of the current situation in which the welding burn-off pickling after welding of stainless steel in the past depends on nitric hydrofluoric acid, which is an extremely dangerous poisonous substance, as a result of research, neutral salt that is safe and harmless. Developed an electrolytic scoring method using as the electrolyte, obtained the patent No. 1544367 under the name of “descaling method of alloy steel”, and restrained the use of the conventional dangerous poisonous and deleterious substance nitric hydrofluoric acid We have developed an electrolyzer that enables safer, harmless welding and burn-out.
The gist of the present invention is a direct current electrolysis method in which glycerol is mixed with a neutral salt solution of phosphoric acid, sulfuric acid, and hydrofluoric acid to form an electrolytic solution, and the treated stainless steel is used as an anode.
According to this method, the above-mentioned burn-out operation can be carried out very effectively, but there is a defect that hexavalent chromium which is highly toxic during electrolysis has been dissolved. The company has developed an epoch-making electrolyte that does not elute hexavalent chromium even when it is electrolyzed with a power supply.
In addition, we developed a groundbreaking power supply for electrolytic treatment that does not elute hexavalent chromium even when using a commercially available neutral salt electrolyte with a risk of elution of hexavalent chromium. Patent No. 1908719 is acquired under the name of “scale removal method”.
The gist of the present invention is characterized in that an inorganic neutral salt solution is used as an electrolytic solution, and the electrolytic treatment is performed with an AC / DC current obtained by superimposing an alternating current with an amplitude equal to or slightly larger than a direct current with a direct current. Thus, the harmful hexavalent chromium eluted at the time of electrolysis is immediately reduced to trivalent chromium and has an excellent effect of detoxification.
Applicant has improved other methods of electrolytic polishing of stainless steel, development of radioactive decontamination treatment by electrolytic method of nuclear equipment, and formation of passive film to give rust prevention effect of stainless steel and measurement of its strength We have been researching the overall surface treatment of stainless steel, including the development of methods.

As one of the above-mentioned welding burn-out treatment forms of stainless steel by electrolysis, a stainless steel welded product in which a plurality of weld lines are constructed is stored in a non-contact state in a stainless steel plate container, The container is filled with an electrolytic solution, the product is immersed, the product is connected to the anode of a DC power source, and the cathode is connected to the container and energized to cause an electrolysis action. There is a so-called immersion electrolysis method that dissolves and removes the burn on the weld line by the action of the anodic dissolution action by this, but in this method, in order to make the current density uniform in each of the plurality of weld lines, the distance between both electrodes The relationship between the product to be processed and the container must be formed in a similar shape because it is necessary to make the container uniform, and it is difficult to manufacture the container. Useless current flows Because, in order to ensure the current required to burn-up had serious drawbacks which will be that of inevitably large capacity power supply is required.
Furthermore, if there is an error in the similar relationship between the product to be processed and the container that accommodates it, there is a drawback that defects such as good and bad irregularities occur in the burn-out finish of the weld line.
Japanese Patent No. 1543867 Japanese Patent No. 1908719 Patent No. 1905254 Japanese Patent No. 2649625 Japanese Patent No. 3484525 JP2003-082495

  The problem to be solved is to solve the various drawbacks associated with the electrolytic burn-out by the above-mentioned immersion method, regardless of the shape of the product to be treated, and the shape, size, material, etc. of the container that accommodates it. Therefore, the present invention aims to provide an electrolytic treatment method that can carry out the welding burn-out operation very effectively without any significant restrictions.

  When removing the weld burn of the stainless steel welded product by the electrolysis method, it is immersed in the electrolytic solution in the container containing the article to be treated and the anode of the DC power source is attached to the article to be treated, or the AC power supply After connecting one pole, connect the other one pole of the power source to a counter electrode made of a stainless steel material coated with an organic or inorganic woven or non-woven fabric as an electrical short-circuit preventing material, With the method of welding and scoring the stainless steel welded product, the welding electrode is melted and removed by causing an electrolysis effect between the counter electrode along the weld line of the workpiece to be moved in sequence. As a means to solve the problem.

  According to the welding burn-off method of the stainless steel welded product of the present invention, in the conventional immersion electrolysis method, the article to be treated and the inner wall surface of the container in which the article is to be accommodated are in a bipolar relationship that causes an electrolytic action. The area of the electrode is inevitably large, and there is a disadvantage that a large-capacity power supply device is naturally required to obtain a required current density. However, the counter electrode in the present invention only needs a small area. Compared to the above, the power supply device with a much smaller capacity can be used. Furthermore, in the conventional method, it is necessary to form the article to be processed and the container in which it should be stored as closely as possible, and this requirement is satisfied. This is extremely difficult, and naturally there is a difference in the distance between the multiple weld lines and the opposing vessel wall, resulting in a difference in strength in the current involved in the electrolysis, and the quality of the weld burnout finish is good. Unevenness often occurred In the method of the invention, while observing the state of burning of each weld line, finish can be processed to each best the so removed by dissolution burnt moved along successively weld line counter. Therefore, there is an advantage that the container for storing the product to be processed is not greatly restricted in terms of shape, size and material.

The working principle of stainless steel welding and scoring by immersion electrolytic method is stainless steel counter electrode with stainless steel treated product as anode and other one as cathode, aramid fiber rich in heat resistance, corrosion resistance and strength, etc. When a woven fabric or non-woven fabric is coated and energized under the presence of a neutral salt or acidic electrolyte, and the counter electrode is slid along the weld line of the article to be treated, an electrolytic reaction occurs between the electrodes. Is generated, and an acid is generated on the weld line, and the weld burn is dissolved and removed by this acid. At this time, since the coating material for the counter electrode is always impregnated with the electrolytic solution in the container that accommodates the article to be treated, the burning operation can be performed intermittently without interrupting the electrolysis. If the welding is by electric welding with argon gas as the shielding gas, neutral salt electrolyte will not interfere with the welding, but if the welding is strong, such as electric welding with carbon dioxide as the shielding gas, I would recommend using an acidic electrolyte. The power supply device is not limited to a DC power supply, and does not hinder the use of an AC power supply or an AC / DC mixed current power supply.
As a material of the container for storing the article to be processed, heat resistant glass or plastic material which is not affected by the electrolyte is suitable. The material of the counter electrode is preferably a stainless steel material such as SUS304, and the shape thereof may be formed according to the state of welding burn. Further, the counter electrode is used with a handle appropriately attached for the sake of manual operation for burn-out work, and the name of this counter electrode is called an electric rod.

As an article to be treated, a cylinder made of SUS304 stainless steel plate with a diameter of 10 cm and a length of 20 cm is prepared, and electric welding using argon gas as a shielding gas as shown in FIG. Four lines were applied to form a black weld burn on each weld line. After the product to be treated is stored in a plastic container prepared in advance as shown in FIG. 1, an electrolytic solution made of an aqueous solution in which 10% sodium tartrate is added to 10% sodium sulfate is injected into the container. A DC power supply anode with a voltage of 20 V is connected to the product to be processed, while an aramid fiber cloth is coated on a counter electrode formed of a stainless steel plate of SUS304 with a width of 3 cm and a length of 6 cm to prevent electrical short circuit. Then, an electric rod having a handle appropriately attached to the counter electrode is placed in the container, and the electrolytic solution is sufficiently contained in the covering material. Then, the cathode of the DC power supply unit is connected to the electric rod and energized.
After that, along with the weld line applied to the product to be processed, the counter electrode surface of the electric rod was manually moved sequentially, and an electrolysis action occurred between the weld line and the counter electrode, and the generation period occurred on the weld line side. It was confirmed that the acid was generated and the weld burn was dissolved and removed in a very short time and beautifully.
According to the treatment method of the present invention, local burn-out operation limited to the weld line is possible, and therefore, there is a great advantage that the consumed current is much smaller than that of the conventional immersion electrolysis method.

It is explanatory drawing which showed the implementation method of this invention. (Example 1) Features (1) The capacity of the power supply may be small. (2) Finishing unevenness is eliminated. It is explanatory drawing which showed the conventional implementation method.

Explanation of symbols

1 Product to be treated 2 Welding line 3 Container (made of plastic)
4 Electrolytic solution 5 Counter electrode coating material 6 Electric bar 7 Container (made of stainless steel)
8 Insulation cloth

Claims (1)

  When electrolytically scavenging stainless steel welded products, a similar or approximated stainless steel piece is applied to the weld line with the treated material immersed in the electrolyte and connected to one pole of a DC or AC power supply. Alternatively, the stainless steel welded product is burned off by applying an energization treatment while being in contact with or in proximity to the weld line in a state of being covered with a glass cloth and connected to another counter electrode, and sequentially moving the electrolytic sites.

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