Dehydrogenation method for steel and steel products, and method for manufacturing steel and steel products

Abstract

The present invention provides a dehydrogenation method for effectively reducing the amount of hydrogen in steel of a common steel material or steel product having a large thickness or a complex shape. The dehydrogenation method for steel material comprises, in a series of steel material manufacturing processes including a steel billet supply process, a steel billet hot working process, a steel material inspection process obtained from the steel billet, and a steel material shipping process, at least one of the steel billet and the steel material at any stage from the supply process to the shipping process is subjected to at least one sonic wave irradiation treatment in such a manner that the sound pressure level of the surface of the steel material or the steel material satisfies 30 dB or more.

Description

Technical Field

[0001] The present invention relates to a dehydrogenation method for reducing the amount of hydrogen inherent in general steel and steel products, and a production method using the dehydrogenation method. The present invention is applicable to all fields where steel products are used, such as railways, automobiles, building materials, and machinery, and contributes to providing steel and steel products in which quality degradation caused by hydrogen is suppressed. Background Art

[0002] In various steel materials such as steel plates, steel sections, steel pipes, and rods and wires manufactured from steel billets, hydrogen intrudes into the steel and remains during or after the manufacturing process. There is no consensus on the effect of this residual hydrogen on the quality of steel materials and steel products manufactured using the steel materials, but from the perspectives of the ductility and bendability of steel materials and steel products, fatigue properties, creep properties, and fracture mechanics properties, there are many reports that the quality of steel materials and steel products is reduced due to residual hydrogen. Therefore, from the perspective of improving the quality of these steel materials and steel products, it is required to reduce the amount of hydrogen in steel.

[0003] As a method for reducing the amount of hydrogen in steel, for example, when manufacturing a thin steel sheet with a thickness of less than 6 mm, a method is known in which the plated thin steel sheet is left at room temperature for several weeks or more or kept at about 100° C. for several tens of hours.

[0004] For example, Patent Document 1 discloses a method of reducing the amount of hydrogen in steel by maintaining the steel at a temperature range of 50° C. to 300° C. for 1800 to 43200 seconds as the final heat treatment after manufacturing a thin steel plate having a thickness of less than 2 mm.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2019 / 188642 Summary of the invention

[0008] Although these methods all show dehydrogenation effects on so-called thin steel sheets, they are difficult to apply to thick steel materials and steel products or steel materials and steel products having complicated shapes after processing.

[0009] In addition, in the dehydrogenation treatment described in Patent Document 1, it takes time for hydrogen to move from the inside of the steel sheet to the surface and to be released from the surface, so the space and time required for the dehydrogenation treatment become a problem in the manufacturing process. Furthermore, there are concerns about changes in the structure and mechanical properties of the steel sheet due to the heating treatment.

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a dehydrogenation method that can be applied to common steel materials and steel products that are thick or have complicated shapes and effectively reduce the amount of hydrogen in steel. Another object of the present invention is to provide a method for manufacturing steel materials and steel products that can suppress the quality reduction caused by residual hydrogen by using the above dehydrogenation method.

[0011] The present inventors have conducted intensive studies to solve the above problems and have found the following: That is, it has been found that the amount of hydrogen inherent in steel (hereinafter referred to as "the amount of hydrogen in steel") can be sufficiently and effectively reduced by irradiating various steel materials and steel products having a large thickness or a complex shape with sound waves under predetermined conditions.

[0012] This is presumably due to the following mechanism. That is, by irradiating the steel material or steel product with sound waves and forcing it to microvibrate, repeated bending deformation is applied to the steel material or steel product. As a result, the lattice spacing on the surface of the steel material or steel product is expanded compared to the inside. Hydrogen in the steel material or steel product diffuses to the surface with a wide lattice spacing and low potential energy, and is released from the surface.

[0013] That is, the present invention has been completed based on the above findings, and the gist of the present invention is as follows.

[0014] 1. A method for dehydrogenating a steel product, comprising: in a series of steel product manufacturing processes including a supply step of supplying a steel billet, a hot working step of hot working the steel billet, an inspection step of inspecting a steel product obtained from the steel billet, and a shipping step of shipping the steel product,

[0015] At least one of the steel billet and the steel material in any stage from the supply step to the shipping step is subjected to at least one treatment of irradiating with sound waves so that the sound pressure level on the surface of the steel billet or the steel material satisfies 30 dB or more.

[0016] Here, the "series of steel manufacturing processes" in the above 1 refers to the usual steel manufacturing process in a steel plant, which refers to the process from the supply process of the solid steel billet to the shipping process of the steel from the steel plant after the casting process and / or ingot casting process in which the steel billet becomes a solid state.

[0017] In the above 1, "steel materials" refer to various target steels supplied in any process after the steel billet supply process of the steel mill, or various target steels in a state ready for inspection and shipment after processing in the steel mill is completed.

[0018] In this specification, the "sound pressure level" can be measured by, for example, the method described later.

[0019] 2. The dehydrogenation method according to item 1 above, wherein the series of steel production processes further includes a cold working step of cold working the steel after the hot working step.

[0020] 3. A method for dehydrogenating a steel product, comprising: in a series of steel product manufacturing processes including a transportation step and a storage step of steel materials shipped from a steel mill and a processing step of processing the steel materials into steel products;

[0021] At least one of the above-mentioned steel materials and steel products at any stage from the above-mentioned shipped steel materials to any stage of the above-mentioned transportation process, storage process and processing process is irradiated with sound waves at least once in a manner so that the sound pressure level on the surface of the steel material or steel product meets 30 dB or more.

[0022] Here, the "series of steel product manufacturing processes" in the above 3 refers to any process after the steel is shipped from the steel plant, for example, it means the process of handling the steel by anyone represented by the carrier, recipient and processor of the steel.

[0023] In the above 3, "steel materials" and "sound pressure level" are in accordance with the above 1. In addition, "steel products" refer to various steel products obtained using steel materials shipped from steel mills.

[0024] 4. The dehydrogenation method according to any one of 1 to 3 above, wherein the sound wave has a frequency of 10 to 100,000 Hz.

[0025] In addition, in this specification, "frequency" can be measured by the method mentioned later, for example.

[0026] 5. The dehydrogenation method according to any one of 1 to 4 above, wherein in the process of irradiating the sound wave, the irradiation time of the sound wave is set to 1 second or longer.

[0027] 6. A method for producing a steel material, comprising carrying out the dehydrogenation method described in 1 above.

[0028] 7. A method for manufacturing a steel product, comprising carrying out the dehydrogenation method described in 3 above.

[0029] According to the present invention, the amount of hydrogen in steel can be effectively reduced for common steel materials and steel products having large thickness or complicated shapes. In addition, according to the present invention, the above-mentioned dehydrogenation method can be used to manufacture steel materials and steel products in which the quality reduction caused by residual hydrogen is suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram showing the structure of the sonic wave irradiation device 10 used in one embodiment of the present invention.

[0031] Figure 2 The figure schematically shows the positional relationship between the steel material 20 and the sound wave irradiation device 10 (including the horn 15) in one embodiment of the present invention, (A) is a figure observed from the side relative to the main propagation direction W of the sound wave, and (B) is a figure observed from the side of the irradiated sound wave relative to the direction W.

[0032] Figure 3 This is a flowchart showing an example of a manufacturing process when the steel material is a thick steel plate.

[0033] Figure 4 This is a flowchart showing an example of a manufacturing process when the steel material is a steel section.

[0034] Figure 5 This is a flowchart showing an example of a manufacturing process when the steel material is a steel pipe.

[0035] Figure 6 This is a flowchart showing an example of a manufacturing process when the steel material is a steel bar.

[0036] Figure 7 This is a flowchart showing an example of a manufacturing process when the steel material is a stainless steel plate. DETAILED DESCRIPTION

[0037] Embodiments of the present invention will be described in detail.

[0038] The following embodiments are preferred examples of the present invention, but the present invention is not limited to these embodiments, and various modifications can be made within the scope of the present invention.

[0039] (Dehydrogenation method)

[0040] [Steel and steel products]

[0041] The steel materials to be targeted in the dehydrogenation method of the present invention refer to various target steels supplied in any process after the supply process of the steel billet material in the steel mill or various target steels that have been processed in the steel mill and are ready for inspection and shipment. Specific examples of steel materials include thick steel plates, steel sections, steel pipes, and bars and wires (i.e., various steel materials other than so-called thin steel plates) manufactured from steel billets as raw materials, and steel materials in the processing stage for obtaining them. Here, bars and wires include steel bars, wire rods, and wires.

[0042] In addition, the steel product used in the dehydrogenation method of the present invention is a steel product obtained by using steel materials shipped from steel mills. Specific examples of steel products include various final products obtained by further processing and assembling thick steel plates, steel sections, steel pipes, and / or bars, wires and wires such as wires (in other words, various steel materials other than so-called thin steel plates), such as ships, guide rails, vehicles, buildings, precision instruments, tools, and intermediate parts thereof.

[0043] Steel and steel products are usually in a solid state.

[0044] When the steel material is a thick steel plate, the plate thickness is 6 mm or more. Examples of the steel section include steels of any shape such as H-shaped, I-shaped, T-shaped, and L-shaped. Examples of the steel pipe include steel pipes of any shape made by any manufacturing method such as forged steel pipes, electric seam steel pipes, seamless steel pipes, and arc welded steel pipes. Examples of the rods and wires include any rod-shaped or wire-shaped steel materials such as rods for general mechanical parts such as shafts, and wires such as piano wires and iron wires.

[0045] [[Ingredients]]

[0046] The component composition of the steel material is not particularly limited. Regardless of the component composition, as long as the steel material is irradiated with sound waves under predetermined conditions, the amount of hydrogen in the steel can be reduced.

[0047] The component composition of the steel material can be an alloy steel with iron (Fe) as the main component and any trace amount of C, Si, Mn, P, S, N, Al, Ti, Nb, V, W, B, Ni, Cr, Mo, Cu, Sn, Sb, Ta, Ca, Mg, Zr, REM (Rare Earth Metal) and other arbitrary alloy elements added depending on the desired properties.

[0048] Furthermore, the component composition of the steel product is not particularly limited, and generally has the same component composition as that of the steel material as a main component composition.

[0049] In the following, regarding specific examples of component compositions, "mass %" is simply expressed as "%".

[0050] Alloy elements added to iron generally have the effect of inhibiting the expansion of lattice spacing in steel. Therefore, when the amount of alloy elements added is excessive, the potential energy difference generated between the surface and the inside of the steel by sound wave irradiation becomes smaller, and the hydrogen reduction rate is easily reduced. When each alloy element (C, Si, Mn, Al, P, S, N, Ni, Cr, Mo, Ti, Nb, V, W, B, Cu, Sn, Sb, Ta, Ca, Mg, Zr, REM) is added to iron, the preferred addition amount from the viewpoint of ensuring the hydrogen reduction rate is as follows.

[0051] The amount of C is preferably 2.000% or less, and more preferably 0.600% or less. On the other hand, due to restrictions in production technology, the amount of C is preferably 0.0005% or more, and more preferably 0.0010% or more.

[0052] The Si content is preferably 7.00% or less, more preferably 2.00% or less, and may be 0%.

[0053] The amount of Mn is preferably 40.00% or less, more preferably 10.00% or less, and may be 0%.

[0054] The amount of P is preferably 0.500% or less, more preferably 0.100% or less, and may be 0%.

[0055] The amount of S is preferably 0.500% or less, more preferably 0.300% or less, further preferably 0.100% or less, and may be 0%.

[0056] The N content is preferably 2.0000% or less, more preferably 0.1000% or less, and may be 0%.

[0057] The Al content is preferably 5.000% or less, and may be 0%.

[0058] The Ti content is preferably 0.600% or less, and may be 0%.

[0059] The Nb content is preferably 1.000% or less, more preferably 0.500% or less, and may be 0%.

[0060] The V content is preferably 0.500% or less, more preferably 0.200% or less, and may be 0%.

[0061] The W content is preferably 10.000% or less, and may be 0%.

[0062] The amount of B is preferably 0.1000% or less, more preferably 0.0100% or less, and may be 0%.

[0063] The Ni content is preferably 40.000% or less, more preferably 1.000% or less, and may be 0%.

[0064] The Cr content is preferably 50.000% or less, more preferably 30.000% or less, and may be 0%.

[0065] The Mo content is preferably 10.000% or less, more preferably 2.000% or less, and may be 0%.

[0066] The Cu content is preferably 5.000% or less, more preferably 1.000% or less, and may be 0%.

[0067] The Sn content is preferably 1.000% or less, and may be 0%.

[0068] The amount of Sb is preferably 1.000% or less, more preferably 0.100% or less, and may be 0%.

[0069] The amount of Ta is preferably 1.000% or less, and may be 0%.

[0070] The amount of Ca is preferably 0.3000% or less, and may be 0%.

[0071] The Mg content is preferably 0.0050% or less, and may be 0%.

[0072] The Zr content is preferably 0.6000% or less, and may be 0%.

[0073] The REM content is preferably 0.0050% or less, and may be 0%.

[0074] In addition, the remainder other than the above-mentioned components may be unavoidable impurities.

[0075] The steel material may be a stainless steel material such as a stainless steel plate, a stainless steel section, a stainless steel pipe, a stainless steel bar or a stainless steel wire, which contains 10% or more Cr in the composition. Similarly, the steel product may be a stainless steel product manufactured using a stainless steel material containing 10% or more Cr in the composition. For example, as an example of the composition of a stainless steel material and a stainless steel product, SUS430 (alloy element content: 0.10% C-0.5Si-0.8Mn-17Cr) may be cited.

[0076] [Steel Manufacturing Process]

[0077] In the dehydrogenation method of steel of the present invention, in a series of steel manufacturing processes including a supply process of supplying steel billets, a hot working process of hot working the steel billets, an inspection process of inspecting steel obtained from the steel billets, and a shipping process of shipping the steel, the steel (or the steel billets according to different processes) at any stage from the supply process to the shipping process is irradiated with sound waves at least once under specified conditions. In this way, by irradiating the target steel in the steel manufacturing process with sound waves, the amount of hydrogen in the steel can be fully and effectively reduced, and the quality reduction caused by residual hydrogen in the various steels finally obtained can be fully suppressed. In addition, by performing sound wave irradiation multiple times, the amount of hydrogen in the steel can be further reduced compared with the case of performing sound wave irradiation only once. Therefore, it is preferred to perform multiple sound wave irradiations more than twice. When performing sound wave irradiation multiple times, sound waves can be irradiated more than twice in one manufacturing process, or sound waves can be irradiated separately in different manufacturing processes, or a combination thereof.

[0078] Furthermore, the dehydrogenation method of the steel material of the present invention can be carried out, for example, by using Figure 1 The acoustic wave irradiation device 10 shown is as follows Figure 2 As shown, the steel material 20 is irradiated with sound waves. Hereinafter, an embodiment of the present invention in which the object of sound wave irradiation is a steel material will be described with reference to the drawings. When the object of sound wave irradiation is a steel billet or a steel product other than steel material, the following contents can also be applied to the steel material.

[0079] [[How sound waves are irradiated]]

[0080] The exposure of steel to sound waves can be done by Figure 1 The general sonic wave irradiation device 10 shown applies sonic waves to any part of a steel material 20 provided in each process described later.

[0081] The sound wave irradiation device 10 generally includes a controller 11, a sound wave oscillator 12, a vibration transducer (speaker) 13, an enhancer (amplifier) ​​14, a speaker 15, and a sound level meter 16. The sound wave oscillator 12 converts an electrical signal having a general frequency (e.g., 50 Hz or 60 Hz) into an electrical signal of a desired frequency, and transmits it to the vibration transducer 13. It should be noted that the voltage is generally AC200 to 240 V, but is amplified to nearly 1000 V inside the sound wave oscillator 12. The electrical signal of the desired frequency transmitted from the sound wave oscillator 12 is converted into mechanical vibration energy by the piezoelectric element located inside the vibration transducer 13, and the mechanical vibration energy is transmitted to the enhancer 14. The enhancer 14 amplifies the amplitude of the vibration energy transmitted from the vibration transducer 13 (or converts it into an optimal amplitude), and transmits it to the speaker 15. The speaker 15 is a component for making the vibration energy transmitted from the enhancer 14 have directivity and propagating it in the air as a directional sound wave.

[0082] As a preferred example, from the viewpoint of irradiating directional sound waves to the steel material, the horn 15 may be a cylindrical member. However, as long as the sound waves can be irradiated under the prescribed conditions, the shape of the horn 15 is not limited to the cylindrical shape. Figure 2 As shown in (A) and (B), one or more sound wave irradiation devices 10 are provided to allow the sound waves to reach any part of the steel material 20, preferably the main surface with a larger area in the steel material from the viewpoint of easily and effectively receiving the desired sound waves. Figure 2 As shown in (A), it is preferred that the main propagation direction W of the sound wave is perpendicular to the irradiated surface or irradiated portion of the steel material 20 (including approximately perpendicular in terms of the nature of the operation and the shape of the steel material, for example, when the irradiated surface is a curved surface, it is perpendicular or approximately perpendicular to its tangent plane). Figure 2As shown in (B), by irradiating the steel material 20 with sound waves from a device group consisting of a plurality of sound wave irradiation devices 10 separated from the surface of the steel material 20 at arbitrary intervals (preferably above the vertical direction), the entire surface of the steel material 20 can be effectively exposed to the sound waves, and the exposure time to the sound waves can be sufficiently ensured when the steel material 20 is passed through the plate. In this way, the irradiation of the sound waves can be performed without contact with the steel material.

[0083] [[Sound wave irradiation conditions]]

[0084] Sound pressure level

[0085] In order to reliably apply vibration to the steel and promote the diffusion of hydrogen, it is important that the sound pressure level on the surface of the steel meets 30 dB or more, preferably 60 dB or more, and more preferably 80 dB or more during the sonic irradiation treatment. On the other hand, considering the performance of the commonly available sonic irradiation device, the sound pressure level on the surface of the steel is usually 150 dB or less, preferably 140 dB or less during the sonic irradiation treatment. Here, the sound pressure level on the surface of the steel 20 can be adjusted by appropriately changing the intensity (e.g., output) of the sound waves generated from the sonic irradiation device 10 and / or the setting position of the sonic irradiation device 10 (i.e., the distance between the sonic irradiation device 10 and the irradiation surface of the steel 20). In addition, the sound pressure level on the surface of the steel 20 can be measured by setting a sound level meter 16 near the surface of each steel 20 irradiated with sound waves and at a position where the distance from the sonic irradiation device 10 is the shortest.

[0086] frequency

[0087] If the frequency of the sound waves irradiated on the steel is less than 10 Hz, the rigidity of the steel hinders the vibration imparted by the sound wave irradiation, does not promote the diffusion of hydrogen in the steel, and it is difficult to sufficiently reduce the amount of hydrogen in the steel. Therefore, the frequency of the sound waves irradiated on the steel is preferably 10 Hz or more, more preferably 100 Hz or more, further preferably 500 Hz or more, and further preferably 1000 Hz or more. On the other hand, if the frequency of the sound waves irradiated on the steel exceeds 100,000 Hz, the generated sound waves are significantly attenuated in the air, and sufficient vibration is not imparted to the surface of the steel, making it difficult to effectively reduce the amount of hydrogen in the steel. Therefore, the frequency of the sound waves irradiated on the steel is preferably 100,000 Hz or less.

[0088] Here, the frequency of the irradiated sound wave can be appropriately set, for example, at the sound wave output side of the sound wave irradiation device 10. In addition, from the viewpoint of improving the effect of delayed fracture resistance due to the frequency, it is preferred that the shortest straight-line distance between the surface of the steel material 20 and the sound wave irradiation device 10 be within 15 m, more preferably within 5 m.

[0089] Irradiation time

[0090] From the viewpoint of desorbing hydrogen from the steel material and sufficiently reducing the amount of hydrogen in the steel, the irradiation time of the sonic wave on the steel material is preferably 1 second or longer, more preferably 5 seconds or longer, and even more preferably 10 seconds or longer in the sonic wave irradiation treatment. On the other hand, from the viewpoint of hindering productivity, the irradiation time of the sonic wave on the steel material is preferably 3600 seconds or shorter, more preferably 1800 seconds or shorter, and even more preferably 900 seconds or shorter.

[0091] In this specification, the irradiation time of the steel material with sound waves refers to the total time that a certain surface of the steel material is exposed to the sound waves during a certain process (such as a hot working process, an inspection process, etc.), and refers to the cumulative time when the surface is exposed to the sound waves from multiple sound wave irradiation devices 10 at one time or when it is exposed to the sound waves multiple times in one process. The irradiation time can be adjusted, for example, by adjusting the irradiation time of a single sound wave irradiation device 10, or by adjusting the number of irradiations of the sound wave irradiation device 10, or by adjusting the number of sound wave irradiation devices 10 constituting the device group. In addition, the irradiation time when the steel material is irradiated with sound waves in the process of passing the steel material through the plate can be adjusted according to the plate passing speed of the steel material and the number of the device group consisting of multiple sound wave irradiation devices 10 along the plate passing direction.

[0092] [[Process of irradiating with sound waves]]

[0093] In the dehydrogenation method of steel, in the steel manufacturing process including the supply process, the hot working process represented by hot rolling, the inspection process and the shipping process, the steel (or steel billet) at any stage from the supply process to the shipping process is irradiated with sound waves at least once according to the above conditions. Here, the steel manufacturing process may further include cold working processes such as cold rolling, heat treatment processes such as annealing, and any other processes specifically performed to obtain each steel in different orders from the supply process to the shipping process. The irradiation of sound waves may be performed at least once in any of the above-mentioned processes.

[0094] Generally, a steel billet and subsequent steel materials are solidified by a casting process or an ingot casting process performed before the above process. The process after the casting process or the ingot casting process to solidify the steel material varies depending on the type of steel material, and a typical process is as follows.

[0095] An example of a thick steel plate manufacturing process is shown in Figure 3 .exist Figure 3 In the manufacturing process of the upper thick steel plate, after the casting process such as the continuous casting process and / or the ingot casting process, the steel billet supply process is carried out; the heat treatment process such as heating; the hot working process such as finishing rolling; other processes such as cooling; the heat treatment process such as normalizing, quenching, and tempering; other processes such as shearing, shot peening, and painting; followed by the inspection process; and the shipping process.

[0096] As long as the sound waves are irradiated under the prescribed conditions, the reduction of the hydrogen content in the steel of the final thick steel plate can be achieved regardless of whether the sound waves are irradiated in any of the above-mentioned processes. However, since hydrogen inevitably invades the steel in each process, from the viewpoint of shipping the steel with the hydrogen content in the steel further reduced, it is preferred to irradiate the sound waves in the shipping process and / or the inspection process, coating process, and shot blasting process adjacent thereto, more preferably in the inspection process and coating process, and even more preferably in the inspection process. Moreover, from the viewpoint of further reducing the hydrogen content in the final steel, it is particularly preferred to irradiate the sound waves in two or more of the above-mentioned processes and the inspection process.

[0097] An example of the manufacturing process of steel sections is shown in Figure 4 .exist Figure 4 In the manufacturing process of the upper steel section, after the casting process such as the continuous casting process and / or the ingot casting process, the steel billet supply process is carried out; the hot working process such as slab rolling; the heat treatment process such as heating; other processes such as oxide film removal (descaling); hot working processes such as hot rolling such as rough rolling and intermediate rolling; other processes such as nipper sawing; hot working processes such as hot rolling such as finish rolling; other processes such as hot sawing, cooling, straightening; then the inspection process; and the shipping process.

[0098] As long as the sound waves are irradiated under the prescribed conditions, the amount of hydrogen in the steel in the final steel section can be reduced regardless of whether the sound waves are irradiated in any of the above processes. However, since hydrogen inevitably invades the steel in each process, from the viewpoint of shipping the steel material in a state where the amount of hydrogen in the steel is further reduced, it is preferred to irradiate the sound waves in the shipping process and / or the inspection process and straightening process adjacent thereto, and it is more preferred to irradiate the sound waves in the inspection process. Moreover, from the viewpoint of further reducing the amount of hydrogen in the final steel, it is particularly preferred to irradiate the sound waves in two or more processes, namely, any of the above processes and the inspection process.

[0099] When the sound waves are irradiated in the straightening process of the steel section, for example, there can be mentioned a method in which the steel section is passed through a straightening machine and the sound waves are irradiated to the steel section using a sound wave irradiation device provided on the outlet side of the straightening machine.

[0100] An example of the production process of a steel pipe is shown in Figure 5 .exist Figure 5 In the manufacturing process of the upper steel pipe, after the casting process such as the continuous casting process and / or the ingot casting process, the steel billet supply process is carried out; the heat treatment process such as heating; the hot working process such as hot rolling; the cold working process such as cold rolling; other processes such as pipe making, forging, welding, etc.; then the inspection process; and the shipping process are carried out.

[0101] As long as the sound waves are irradiated under the prescribed conditions, the reduction of the hydrogen content in the steel in the final steel pipe can be achieved regardless of whether the sound waves are irradiated in any of the above processes. However, since hydrogen inevitably invades the steel in each process, from the viewpoint of shipping the steel material in a state where the hydrogen content in the steel is further reduced, it is preferred to irradiate the sound waves in the shipping process and / or the inspection process, welding process, and forging process adjacent thereto, more preferably in the inspection process and welding process, and even more preferably in the inspection process. Moreover, from the viewpoint of further reducing the hydrogen content in the final steel, it is particularly preferred to irradiate the sound waves in two or more of the above processes and the inspection process.

[0102] An example of the manufacturing process of a rod and wire is shown in Figure 6 .exist Figure 6 In the manufacturing process of the upper bar and wire, after the casting process such as the continuous casting process and / or the ingot casting process, the steel billet supply process is carried out; the heat treatment process such as heating; the hot working process such as hot rolling; other processes such as cooling, shot peening, grinding, etc.; then the inspection process; and the shipping process are carried out.

[0103] As long as the sonic waves are irradiated under the prescribed conditions, the amount of hydrogen in the steel in the final rod and wire can be reduced regardless of whether the sonic waves are irradiated in any of the above-mentioned processes. However, since hydrogen inevitably enters the steel in each process, from the viewpoint of shipping the steel material in a state where the amount of hydrogen in the steel is further reduced, it is preferred to irradiate the sonic waves in the shipping process and / or the inspection process, grinding process, and shot peening process adjacent thereto, more preferably in the inspection process and grinding process, and even more preferably in the inspection process. Moreover, from the viewpoint of further reducing the amount of hydrogen in the final steel, it is particularly preferred to irradiate the sonic waves in two or more of any of the above-mentioned processes and the inspection process.

[0104] As an example of a more specific process for manufacturing a rod and wire, the rod and wire are operated in the following flow: passing through a heating furnace (heat treatment process); passing through a rough rolling mill (hot working process); passing through an intermediate water cooling zone (another process); passing through a finishing rolling mill (hot working process); passing through a final cooling zone (another process); and coiling (another process). Here, for example, a method of installing a sonic wave irradiation device between the final cooling zone and the coil winding production line and irradiating with sonic waves can be cited.

[0105] As a more specific example, an example of a production process of a stainless steel thick steel plate in which the thick steel plate is made of stainless steel is shown in Figure 7 .exist Figure 7 In the manufacturing process of the stainless steel thick plate at the top, after the casting process such as the continuous casting process and / or the ingot casting process, the steel billet supply process is carried out; the hot working process such as hot rolling; the cold working process such as cold rolling; the heat treatment process such as annealing; other processes such as pickling and grinding; then the inspection process; and the shipping process.

[0106] As long as the sound waves are irradiated under the prescribed conditions, the reduction of the hydrogen content in the steel of the final stainless steel plate can be achieved regardless of whether the sound waves are irradiated in any of the above processes. However, since hydrogen inevitably invades the steel in each process, from the viewpoint of shipping the steel in a state where the hydrogen content in the steel is further reduced, it is preferred to irradiate the sound waves in the shipping process and / or the inspection process, grinding process, and pickling process close thereto, more preferably in the inspection process and grinding process, and even more preferably in the inspection process. Moreover, from the viewpoint of further reducing the hydrogen content in the final steel, it is particularly preferred to irradiate the sound waves in more than two of the above processes and the inspection process.

[0107] [Manufacturing process of steel products]

[0108] In the dehydrogenation method of steel products of the present invention, in a series of steel product manufacturing processes including a transportation process, a storage process of steel products shipped from a steel mill, and a processing process of processing steel products to produce steel products, the steel products (or steel products according to the processes) at any stage from the shipped steel products to any of the transportation process, the storage process, and the processing process are irradiated with sound waves at least once under predetermined conditions. In this way, by irradiating the target steel with sound waves during the steel product manufacturing process, the amount of hydrogen in the steel can be sufficiently and effectively reduced, and the quality degradation caused by residual hydrogen in various steel products finally obtained can be sufficiently suppressed.

[0109] The dehydrogenation method of the steel product of the present invention can be carried out similarly to the dehydrogenation method of the above-mentioned steel material by, for example, using Figure 1 The acoustic wave irradiation device 10 shown is as follows Figure 2 As shown, the steel material 20 or the steel product 20 is irradiated with sound waves to implement the method.

[0110] The irradiation method of sound waves in the dehydrogenation method of steel products of the present invention, and the irradiation conditions of sound waves such as sound pressure level, frequency, and irradiation time can be the same as those of the above-mentioned dehydrogenation method of steel products. By irradiating with sound waves in any of the transportation process, storage process, and processing process in the manufacturing process of steel products, the amount of hydrogen in the steel in the final steel product can be reduced.

[0111] [Hydrogen content in steel]

[0112] Furthermore, in the steel material or steel product subjected to the dehydrogenation treatment according to the above method, since the sound waves are irradiated to the surface of the steel material or steel product and forced to vibrate, the inherent hydrogen in the steel is effectively and sufficiently reduced. It is believed that this is because the surface lattice spacing is expanded by forcibly vibrating the steel material or steel product as described above, and the hydrogen inside the steel that has expanded the lattice spacing is induced to diffuse to the favorable tensile side with lower potential energy, thereby promoting hydrogen diffusion. The effect of reducing the amount of hydrogen in steel by dehydrogenation treatment can be evaluated by the hydrogen reduction rate represented by the following formula (1) or (1)'.

[0113] Hydrogen reduction rate (%) = (AB) / A×100···(1)

[0114] or,

[0115] Hydrogen depletion rate (%) = (A'-B') / A'×100···(1)'

[0116] here,

[0117] A: Hydrogen content (ppm) in steel produced without dehydrogenation by sonication,

[0118] B: Hydrogen content (ppm) in steel produced by dehydrogenation method using sonic irradiation,

[0119] A': hydrogen content in steel products manufactured without dehydrogenation by sonication (ppm),

[0120] B': The amount of hydrogen in steel (ppm) of a steel product manufactured by a dehydrogenation method using sonication.

[0121] In this specification, when the hydrogen reduction rate calculated according to the above formula (1) and (1)' is 10% or more, it is judged that the hydrogen content in steel of the steel material or steel product has been sufficiently reduced.

[0122] In addition, the amount of hydrogen in steel in steel materials and steel products can be measured by the method described in the examples described later.

[0123] (Manufacturing method)

[0124] In the method for manufacturing the steel material and steel product of the present invention, the above-mentioned dehydrogenation method is implemented. In other words, in the manufacturing method of the present invention, the steel billet, steel material or steel product is irradiated with sound waves under the above-mentioned prescribed conditions to sufficiently reduce the amount of hydrogen in the steel, thereby manufacturing the steel material or steel product, and thus the quality degradation of the various steel materials and steel products obtained due to residual hydrogen is sufficiently suppressed.

[0125] Example

[0126] Below, based on embodiment, the present invention is specifically described.It should be noted that the following examples represent a preferred example of the present invention, and the present invention is not limited in any way.In addition, the following examples can also be changed to implement within the scope that can meet the gist of the present invention, and such a mode is also included in the technical scope of the present invention.

[0127] (Example 1)

[0128] In the manufacturing process of thick steel plates, steel sections, steel pipes and bars, various steel products were manufactured by irradiating steel billets or steel products with or without irradiating them with sound waves according to the conditions shown in Tables 1 to 4. The steel billets and steel products were in a solid state in each process.

[0129] In addition, the number of times of irradiation with sound waves was once in each step.

[0130] For each of the obtained steel products, thick steel plates, steel sections, steel pipes, and rods and wires, 100 test pieces with a length of 30 mm and a width of 5 mm were collected. For these test pieces, the amount of hydrogen in the steel was measured by thermal desorption spectroscopy (TDS). Then, the average amount of hydrogen in steel (ppm) of the 100 steel products was calculated based on the measured amount of hydrogen in steel, and the hydrogen reduction rate (%) was calculated based on the average amount of hydrogen in steel and the above formula (1).

[0131] The results are shown in Tables 1 to 4.

[0132] (Example 2)

[0133] In the manufacturing process of various steel products obtained from thick steel plates, steel sections, steel pipes or bars (the process after the steel product shipping process), various steel products were manufactured by irradiating steel materials with sound waves or without irradiating them with sound waves according to the conditions shown in Table 5. All steel materials were in a solid state.

[0134] In addition, the number of times of irradiation with sound waves was once in each step.

[0135] In the case of thick steel plates, steel products for frames of buildings and industrial machinery are manufactured through processing steps such as shearing, bending, punching, and welding, which are represented by laser cutting. During manufacturing, sound waves are irradiated during the transportation and storage steps of steel materials or during laser cutting as a processing step.

[0136] In the case of steel, H-shaped steel products are manufactured through processing steps such as shearing and grinding. During the manufacturing process, sound waves are irradiated during the transportation process, storage process, or grinding process as a processing process of the steel.

[0137] In the case of steel pipes, steel products for automobile bumper beams are manufactured through processing steps such as shearing, bending, and welding, which are represented by laser cutting. During manufacturing, sound waves are irradiated during the transportation and storage steps of steel materials or during laser cutting, which is a processing step.

[0138] In the case of bars and wires, steel products for bolts are manufactured through processing steps such as cold heading, heat treatment, and grinding. During manufacturing, sound waves are irradiated during the transportation process, storage process, or grinding process as a processing step of the steel material.

[0139] For each steel product obtained from thick steel plates, steel shapes, steel pipes or bars, the hydrogen reduction rate (%) was calculated in the same manner as in Example 1 based on the calculated average amount of hydrogen in the steel and the above formula (1)'.

[0140] The results are shown in Table 5.

[0141]

[0142]

[0143]

[0144]

[0145]

[0146] As can be seen from Tables 1 to 5, in the steel materials and steel products of the examples of the present invention subjected to the sonication treatment under the prescribed conditions, the hydrogen reduction rate was 10% or more, and the hydrogen content in the steel was sufficiently reduced.

[0147] On the other hand, in the comparative examples where sound waves were not irradiated or the sound pressure level of irradiation was less than 30 dB, the average amount of hydrogen in the steel was higher than that in the examples of the present invention for each steel material or steel product, and the hydrogen reduction rate remained at a low level of less than 10%.

[0148] It can be seen from this that the dehydrogenation method and manufacturing method of the present invention do not rely on heat treatment that may cause changes in the structure and mechanical properties of steel materials and steel products, and can effectively and sufficiently reduce the amount of hydrogen in steel materials and steel products, and can effectively and sufficiently reduce the quality degradation of steel materials and steel products caused by hydrogen, and are useful.

[0149] Industrial Applicability

[0150] According to the present invention, the amount of hydrogen in steel can be effectively reduced without changing the mechanical properties of general steel materials and steel products with large thickness or complex shapes. In addition, according to the present invention, the above-mentioned dehydrogenation method can be used to produce steel materials and steel products with suppressed quality degradation caused by residual hydrogen.

[0151] Explanation of symbols

[0152] 10. Sound wave irradiation device

[0153] 11 Controller

[0154] 12. Acoustic transmitter

[0155] 13. Vibration transducer

[0156] 14 Enhancer

[0157] 15 Speaker

[0158] 16 Sound Level Meter

[0159] 20 Steel billets, steel products, steel products

Claims

1. A method for dehydrogenating a steel product, comprising: in a series of steel product manufacturing processes including a supply step of supplying a steel billet, a hot working step of hot working the steel billet, an inspection step of inspecting a steel product obtained from the steel billet, and a shipping step of shipping the steel product, At least one of the steel billet and the steel material at any stage from the supply process to the shipping process is subjected to at least one non-contact acoustic wave irradiation treatment without accompanying heat treatment in a manner such that the sound pressure level on the surface of the steel material or the steel material satisfies 30 dB or more, and the acoustic wave irradiated in the non-contact acoustic wave irradiation treatment is generated by an acoustic wave irradiation device separated from the surface and propagated in the air.

2. The dehydrogenation method according to claim 1, wherein: The series of steel material manufacturing processes further includes a cold working step of cold working the steel material after the hot working step.

3. A method for dehydrogenating a steel product, comprising: in a series of steel product manufacturing processes including a transportation step and a storage step of steel materials shipped from a steel mill and a processing step of processing the steel materials into steel products, For at least one of the steel materials and steel products at any stage from the shipped steel materials to any stage of the transportation process, storage process and processing process, non-contact acoustic wave irradiation treatment is performed at least once without accompanying heat treatment in a manner such that the sound pressure level on the surface of the steel material or steel product meets 30 dB or above, and the acoustic wave irradiated in the non-contact acoustic wave irradiation treatment is generated by an acoustic wave irradiation device separated from the surface and propagated in the air.

4. The dehydrogenation method according to any one of claims 1 to 3, wherein The sound wave has a frequency of 10 to 100,000 Hz.

5. The dehydrogenation method according to any one of claims 1 to 3, wherein In the process of irradiating the acoustic wave, the irradiation time of the acoustic wave is set to 1 second or longer.

6. A method for manufacturing steel, comprising carrying out the dehydrogenation method according to claim 1.

7. A method for manufacturing a steel product, comprising implementing the dehydrogenation method according to claim 3.

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