JP6259666B2 - Manufacturing method of stainless clad steel - Google Patents

Description

  The present invention relates to a method for manufacturing a stainless clad steel material by joining stainless clad steel plates.

  For example, steel pipe piles are used for the foundations of offshore structures such as piers, quay walls and breakwaters in harbor facilities, but steel pipe piles are constantly exposed to seawater, and the corrosive environment is particularly severe in the splash and tidal zones. It has become a thing.

  Therefore, in general, by providing a coating such as epoxy resin or urethane on the steel pipe pile, or by using seawater-resistant stainless steel or titanium clad steel for the steel pipe pile as a technique that is more durable than the coating, Has improved.

  Patent Document 1 discloses a method for manufacturing a stainless clad steel pipe with improved corrosivity. By using this stainless clad steel pipe for steel pipe piles, the service life will be longer compared to the other methods described above, maintenance work can be reduced, and sufficient for external impacts such as collision of ships and driftwood. It is possible to ensure strength. Furthermore, stainless steel clad steel is advantageous compared to titanium clad steel because it is less expensive and has a simple welded structure.

JP 2005-133125 A

  However, there has been no example in which the stainless clad steel pipe described in Patent Document 1 has been applied to an actual structure. Further, when this stainless clad steel pipe is applied to an actual structure, if it is necessary to make it long, the short pipe of the stainless clad steel pipe is welded and succeeded. However, when welding a stainless clad steel pipe, there is a possibility that sensitization may occur in the heat-affected portion of the stainless steel, and a solution heat treatment is required after pipe making. Therefore, dedicated equipment is required, resulting in a significant cost increase. In addition, when the solution heat treatment cannot be performed sufficiently, it is necessary to apply heavy anticorrosion coating or cathodic protection, and cost increase is unavoidable.

  This invention is made | formed in view of such a situation, and it aims at providing the manufacturing method of the stainless clad steel material which can manufacture a stainless clad steel material at low cost.

In order to solve the above problems, the present invention employs the following means.
That is, the manufacturing method of a stainless clad steel material according to the present invention includes a groove processing step of performing groove processing on a clad steel plate using SUS312L or NAS354N stainless steel as a combination material and carbon steel as a base material. After joining the clad steel plates subjected to pre-processing, joining by welding from the laminated material side by arc welding using 100% CO2 gas as a shielding gas , after the groove processing step, and And a curing step of covering the surface of the laminated material with a sheet, which is performed before the joining step, and in the joining step, an amount of heat input when welding the base material is 40 kJ / cm or less, The heat input when welding the material is 10 kJ / cm or more and 20 kJ / cm or less.

As described above, the amount of heat input to the base material in the joining process is set to 40 kJ / cm or less, and the amount of heat input to the laminated material is set to 10 kJ / cm or more and 20 kJ / cm or less to obtain sufficient penetration in the welded portion. And the amount of heat input to the laminated material made of stainless steel can be suppressed. In addition, 100% CO2 gas as the shielding gas expands the cross-sectional shape of the weld bead at the welded portion to the bottom of the pan, enabling welding joining while preventing poor fusion at the end of the welded portion. Become. Therefore, it is possible to prevent the occurrence of internal defects during welding, and to join while suppressing the occurrence of sensitization in the laminated material. Therefore, when manufacturing a long stainless clad steel material, it is not necessary to perform a solution heat treatment, and dedicated equipment is not required.
In addition, such a curing process can prevent foreign matters from adhering to the laminated material during bonding.

  In the joining step, flux cored arc welding may be used.

  By performing flux cored arc welding in this way, it is possible to ensure welding quality.

  Furthermore, the manufacturing method of the stainless clad steel material according to the present invention may further include a finishing step of polishing the welded portion and pickling after the joining step.

  Thus, the welding scale can be removed by polishing and pickling after welding.

  Further, in the method for producing a stainless clad steel material according to the present invention, the splicing adhesion preventing agent is applied to the surface of the laminated material around the welded portion after the groove processing step and before the joining step. A preparation step may be further provided.

  By such a joint preparation step, it is possible to prevent spatter generated during welding from adhering to the surface of the laminated material.

  Further, in the groove processing step, a cutback process may be performed in which the laminated material is removed from the end surface on the welded portion side by a predetermined distance.

  By such a cutback process, it is possible to prevent the welding material used for welding the base material from coming into contact with the laminated material.

According to the method for producing a stainless clad steel material according to claim 1, since it is not necessary to perform a solution heat treatment, it is possible to produce a stainless clad steel material at a reduced cost. Moreover, it leads to further quality improvement of the stainless clad steel material.

  Moreover, according to the manufacturing method of the stainless clad steel material of Claim 2, it leads to the quality improvement of a stainless clad steel material.

  Furthermore, according to the method for producing a stainless clad steel material according to claim 3, the quality of the stainless clad steel material is further improved.

  Moreover, according to the manufacturing method of the stainless clad steel material of Claim 4, it leads to the further quality improvement of stainless clad steel material.

Moreover, according to the manufacturing method of the stainless clad steel material of Claim 5 , it leads to the further quality improvement of stainless clad steel material.

1 is an overall schematic view of a short tube of a stainless clad steel material produced by a method for producing a stainless clad steel material according to an embodiment of the present invention. It is a flowchart which shows the procedure of the manufacturing method of the stainless clad steel material which concerns on embodiment of this invention. It is the schematic of the principal part of the clad steel plate at the time of performing a groove processing process and a pipe making process regarding the manufacturing method of the stainless clad steel material which concerns on embodiment of this invention. It is the schematic of the principal part of the clad steel plate which shows a joining process to (a), (b), (c), (d) in time series regarding the manufacturing method of the stainless clad steel material which concerns on embodiment of this invention.

Hereinafter, the manufacturing method of the stainless clad steel material 100 which concerns on embodiment of this invention is demonstrated. Here, first, the manufactured stainless clad steel material 100 will be described.
As shown in FIG. 1, a stainless clad steel material 100 is a short tube of a stainless clad steel tube formed from a clad steel plate 1 with a stainless steel of SUS312L or NAS354N as a laminated material 2 and a base material 3 of, for example, SM490YB or the like. is there.
And this stainless clad steel material 100 is applied to the steel pipe pile used as the foundation of an offshore structure, for example.

As shown in FIG. 2, the manufacturing method of the stainless clad steel material 100 forms a groove processing step S1 for performing groove processing on the clad steel plate 1, a curing step S2 for curing the clad tube, and the clad steel plate 1 in a tubular shape. And a tube forming step S3.
Furthermore, the manufacturing method of this stainless clad steel material 100 is performed after joining preparation process S4 performed after pipe making process S3, joining process S5 which performs welding joining after that, and forms the above-mentioned short pipe, and joining process S5. And finishing step S6.

  First, the groove processing step S1 is executed. That is, as shown in FIG. 3, groove processing by mechanical cutting is performed on the end surface 5 of the clad steel plate 1 so that the groove shape becomes an X-shaped groove. Further, as shown in FIG. 3A, the end surface 5 is subjected to a cutback process for removing the laminated material 2 by a predetermined distance more than the base material 3 so as to be separated from the end surface 5. Is preferred.

  Next, a curing step S2 is performed as shown in FIG. That is, except for the vicinity of the end face 5 subjected to the groove processing, a sheet 6 such as polyethylene is adhered to the surface 2a of the laminated material 2 to cover the surface 2a.

  Then, as shown in FIG. 3, the tube forming step S3 is executed. That is, the clad steel plate 1 is formed in a tubular shape centered on the axis O using a bending roller so that the surface 2a of the laminated material 2 is positioned on the outer side in the radial direction. At this time, the end faces 5 subjected to the groove processing are abutted in the circumferential direction of the axis O.

  And joining preparation process S4 is performed. That is, the spatter adhesion preventing agent 4 is applied to the surface 2a of the laminated material 2 around the end surface 5 where the sheet 6 is not adhered in the curing step S2 (position to be a welded portion). The spatter adhesion preventing agent 4 is, for example, a ceramic heat resistant coating agent.

Next, joining process S5 is performed. That is, the end surfaces 5 of the clad steel plate 1 formed into a tubular shape are joined to each other by performing flux cored arc welding (hereinafter referred to as FCAW welding) on a longitudinal seam formed as a seam. And a short tube is formed.
The shielding gas used at this time is 100% CO ₂ gas.

  More specifically, in this joining step S5, as shown in FIG. 4A, first, the base materials 3 are moved from the outside in the radial direction of the axis O at the outer surface side portion 5a of the end surface 5 where the X-shaped groove is formed. Join using welding material for carbon steel. Thereafter, as shown in FIG. 4B, air arc gouging is performed on the inner surface side portion 5b of the end surface 5 on which the X-shaped groove is formed, and the poorly welded portion is picked up.

Furthermore, as shown in FIG.4 (c), the base materials 3 of the inner surface side part 5b are joined from the radial direction inner side of the axis line O using the welding material for carbon steel materials.
Thereafter, as shown in FIG. 4 (d), the mating members 2 of the outer surface side portion 5 a are joined from the outside in the radial direction of the axis O using a welding material for stainless steel.
As the welding material for stainless steel, Inconel 625 (registered trademark) is used when the bonding material 2 is SUS312L, and Hastelloy C276 (registered trademark) is used when the bonding material 2 is NAS354N. In the case of joining SUS312L and NAS354N, it is preferable to use Inconel 625 (registered trademark). The components of Inconel 625 (registered trademark) are shown in the upper part of Table 1, and the components of Hastelloy C276 (registered trademark) are shown in the lower part of Table 1.

  Here, as welding conditions in the joining step S5, the heat input when welding the base material 3 is set to 40 [kJ / cm] or less, and the heat input when welding the laminated material 2 is 10. [KJ / cm] or more and 20 [kJ / cm] or less. These numerical values are set based on the results in the examples described later.

  Finally, a finishing step S6 is performed in which the welded portion is polished and pickled. That is, the weld bead portion of the laminated material 2 and the heat affected zone around it are polished and washed with an acid solution.

  In addition, although not shown in figure, the groove processing process S1 mentioned above is performed with respect to the end surface of the axis O direction in a short pipe, and after that, curing process S2, joining preparation process S4, joining process S5, and finishing process S6 are performed. Do the same. In this way, a long stainless clad steel pipe is manufactured by joining a plurality of short pipes. At this time, the welding of the circumferential seam that becomes a seam when the short pipe is abutted in the direction of the axis O is performed while rotating on a urethane turning roller, for example.

  According to such a manufacturing method of the stainless clad steel material 100, the heat input amount to the base material 3 is 40 kJ / cm or less in the joining step S5, and the heat input amount to the laminated material 2 is 10 kJ / cm or more, By setting it to 20 [kJ / cm] or less, sufficient penetration can be obtained in the welded portion. Further, the amount of heat input to the stainless steel laminated material 2 can be suppressed.

For this reason, welding joining is possible while preventing the occurrence of sensitization in the laminated material 2 while preventing the occurrence of internal defects during welding. Therefore, it is not necessary to perform a solution heat treatment when welding a vertical seam when manufacturing a short pipe.
Similarly, it is not necessary to perform a solution heat treatment when a long stainless clad steel pipe is manufactured as the stainless clad steel material 100 by welding the circumferential seam by butting the short pipes.

  As a result, a large dedicated facility for performing a solution heat treatment becomes unnecessary. In addition, since no solution heat treatment is required, there is no restriction on the size of the short tube that can be manufactured, and variations in the short tube size increase. Specifically, the clad steel plate 1 can be piped so that the short tube length becomes the maximum value of the plate width dimension of the clad steel plate 1.

Also, by performing FCAW welding using 100% CO ₂ shielding gas, the cross-sectional shape of the weld bead at the welded portion expands to the bottom of the pan, while preventing poor fusion at the end of the welded portion. Can be welded together, leading to improved quality of the stainless clad steel material 100.

  Further, by performing polishing and pickling in the finishing step S6, it becomes possible to remove the welding scale, and by applying the spatter adhesion preventing agent 4, spatter generated during welding adheres to the surface 2a of the bonding material 2. Can be prevented. For this reason, it leads to the further quality improvement of the stainless clad steel material 100.

  Furthermore, when the clad steel plate 1 is piped by the curing step S2, it is possible to prevent adhesion of foreign matter to the laminated material 2, and for carbon steel when welding the base material 3 by cutback processing. The welding material can be prevented from coming into contact with the laminated material 2. Therefore, the quality of the welded portion is improved, and the quality of the stainless clad steel material 100 is further improved.

  According to the method for manufacturing the stainless clad steel material 100 of the present embodiment, it is possible to manufacture the stainless clad steel material 100 while suppressing costs by eliminating the need for solution heat treatment.

Although the embodiment of the present invention has been described in detail above, some design changes can be made without departing from the technical idea of the present invention.
For example, in the above-described embodiment, the groove shape processed in the groove processing step S1 is not limited to the X-shaped groove.

  The joining step S5 is not limited to the case where FCAW welding is used, but gas shield arc welding other than FCAW welding, submerged arc welding, covering arc welding, or the like is applied to the base material 3 portion, and the laminated material 2 portion is applied. Gas shield arc welding, TIG welding, plasma arc welding, or the like other than FCAW welding may be applied.

  Further, in the above-described embodiment, the case where the stainless clad steel material 100 is a steel pipe has been described so as to be applicable to a steel pipe pile that is a foundation of an offshore foundation structure. However, the present invention is not limited to such a case, and for example, it can be manufactured as a large steel plate so as to be applicable to a large planar structure such as a pontoon. In this case, the above-described tube forming step S3 is not necessary.

〔Example〕
Here, as shown in Table 2 , FCAW welding was performed on stainless steel using 100% CO ₂ gas as a shielding gas, and by nondestructive inspection (UT (ultrasonic inspection), RT (radiation transmission inspection)). An experiment was conducted to inspect the presence or absence of welding defects.

  In the case of Case 1, that is, when the heat input amount is 9.450 [kJ / cm 2], both the UT inspection and the RT inspection were rejected. This is thought to be due to poor fusion due to the heat input being too small.

  In the case of case 3, that is, when the heat input was 23.040 [kJ / cm 2], both the UT inspection and the RT inspection passed. However, since the amount of heat input is too large, the results of CPT (critical pitting corrosion generation temperature) and CCT (critical crevice corrosion generation temperature) are undesirable. Therefore, in case 3, it is necessary to improve the corrosion resistance by solution heat treatment.

  Here, in case 2, that is, when the heat input is 13.660 [kJ / cm 2], it was found that both the UT inspection and the RT inspection passed, and sufficient corrosion resistance was obtained. Furthermore, in the case 2, it was confirmed that the fatigue strength of the mechanical properties satisfies the D grade of the fatigue design curve and satisfies the standard of JIS A5525 (steel pipe pile).

  Based on such results, in the above-described embodiment, the heat input when welding the laminated material 2 in the joining step S5 is set to 10 [kJ / cm] or more and 20 [kJ / cm] or less.

In addition, as shown in Table 3 , the type of shield gas is changed under the condition that the heat input when welding the laminated material 2 is 10 [kJ / cm] or more and 20 [kJ / cm] or less. The steel was subjected to FCAW welding, and an experiment was conducted to inspect for the occurrence of welding defects.

As in Cases 1 to 3, when 100% CO ₂ gas was used for the shielding gas, all of the corrosion resistance, mechanical properties, internal defects, and appearance were acceptable. On the other hand, in the case of using mixed gas of 20% of the CO ₂ gas and 80% Ar gas to the shield gas, the result of RT test is failed, it was confirmed that the internal defect occurs.

Based on such results, in the above-described embodiment, 100% CO ₂ gas is used as the shielding gas in the joining step S5.

As shown in Table 4 , carbon steel was subjected to submerged arc welding using 100% CO ₂ gas as a shielding gas, and appearance inspection and corrosion resistance evaluation were performed.

  As a result of the experiment, in the case 3, that is, when the heat input amount is 49.2 [kJ / cm 2], the result of the appearance inspection is poor. This is because the surface of the welded portion after the carbon steel is welded is not smooth, and the welding defect is caused when the base material 3 is welded and the laminated material 2 is further welded as in the above-described embodiment. This is because it may occur.

  On the other hand, when the heat input amount of Case 1 was 27.8 [kJ / cm 2] and when the heat input amount of Case 2 was 35.2 [kJ / cm 2], the result of the appearance inspection was good. .

In addition, in the corrosion resistance evaluation, it passed in any case 1 to 3. In this corrosion resistance evaluation, the pitting potential is set to a potential against SSE of 100 [μA / cm ² ] in a sodium chloride aqueous solution of 60 [° C.] and 5.6 [%], and 900 [mV] or more. Was passed.
Based on such results, in the above-described embodiment, the amount of heat input when welding the base material 3 in the joining step S5 is set to 40 [kJ / cm] or less.

DESCRIPTION OF SYMBOLS 1 ... Clad steel plate 2 ... Laminated material 2a ... Surface 3 ... Base material 4 ... Spatter adhesion prevention agent 5 ... End surface 5a ... Outer surface side part 5b ... Inner surface side part 6 ... Sheet S1 ... Groove processing process S2 ... Curing process S3 ... pipe making process S4 ... joining preparation process S5 ... joining process S6 ... finishing process 100 ... stainless clad steel material O ... axis

Claims (5)

A groove processing step of performing groove processing on a clad steel plate using SUS312L or NAS354N stainless steel as a combination material and carbon steel as a base material;
Joining the clad steel plates that have been subjected to the groove processing, joining by welding from the mating material side by arc welding using 100% CO2 gas as a shielding gas;
A curing step that is performed after the groove processing step and before the joining step, and covers the surface of the laminated material with a sheet,
With
In the joining step, the heat input when welding the base metal is 40 kJ / cm or less, and the heat input when welding the laminated material is 10 kJ / cm or more and 20 kJ / cm or less. A method for producing a stainless clad steel material.   The method for producing a stainless clad steel material according to claim 1, wherein flux cored arc welding is used in the joining step.   The method for producing a stainless clad steel material according to claim 1, further comprising a finishing step of polishing the welded portion and performing pickling after the joining step.   The apparatus further comprises a joining preparation step of applying a spatter adhesion preventing agent to the surface of the laminated material around the welded portion after the groove processing step and before the joining step. 4. The method for producing a stainless clad steel material according to any one of 3 above. In the groove processing step, a stainless clad steel according to claim 1, any one of 4, characterized in that the cut-back process is performed to a predetermined distance removing the cladding material from the end face of the welded portion side Production method.

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