WO2017154796A1 - Procédé permettant la fabrication de matériau en acier trempé - Google Patents

Procédé permettant la fabrication de matériau en acier trempé Download PDF

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Publication number
WO2017154796A1
WO2017154796A1 PCT/JP2017/008622 JP2017008622W WO2017154796A1 WO 2017154796 A1 WO2017154796 A1 WO 2017154796A1 JP 2017008622 W JP2017008622 W JP 2017008622W WO 2017154796 A1 WO2017154796 A1 WO 2017154796A1
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Prior art keywords
steel material
oxide film
heating
manufacturing
steel
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PCT/JP2017/008622
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English (en)
Japanese (ja)
Inventor
直明 嶋田
嘉明 中澤
雄也 金井田
茂貴 山下
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新日鐵住金株式会社
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Priority claimed from JP2017028375A external-priority patent/JP6210172B2/ja
Priority claimed from JP2017028374A external-priority patent/JP6210171B2/ja
Application filed by 新日鐵住金株式会社 filed Critical 新日鐵住金株式会社
Publication of WO2017154796A1 publication Critical patent/WO2017154796A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D7/00—Bending rods, profiles, or tubes
    • B21D7/16—Auxiliary equipment, e.g. for heating or cooling of bends
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/68—Temporary coatings or embedding materials applied before or during heat treatment
    • C21D1/70—Temporary coatings or embedding materials applied before or during heat treatment while heating or quenching
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/50—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for welded joints
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese

Definitions

  • This disclosure relates to a method of manufacturing a hardened steel material.
  • the present inventors are researching and developing a three-dimensional hot bending and quenching (3DQ) technology that heats an arbitrary part of a steel material, bends it into an arbitrary shape, and increases the strength by quenching.
  • 3DQ is a technique suitably used for manufacturing vehicle structural materials and the like.
  • the structural material manufactured by 3DQ has the features of light weight and high strength. There is a feature that a mold is not necessary for manufacturing a structural material or the like by 3DQ.
  • the heating device and the cooling device are arranged close to each other.
  • a bending moment in an arbitrary direction is given to a high temperature portion generated in the steel material between the heating device and the cooling device while passing the steel material in the order of the heating device and the cooling device.
  • any part of steel can be bent into any shape and processed into a hardened member.
  • the bending moment applying means is not particularly limited.
  • a movable roller die arranged downstream of the cooling device in the steel feeding direction as in International Publication No. 2006/093006, and a steel material downstream in the steel feeding direction as in International Publication No. 2010/050460 A chuck and a manipulator attached to the end, and a chuck and a manipulator attached to the end of the steel on the upstream side in the steel feed direction as in International Publication No. 2011/007810 are exemplified.
  • 3DQ allows not only bending but also twisting.
  • International Publication No. 2006/093006 and International Publication No. 2011/007810 disclose that twist processing is possible with 3DQ.
  • WO 2010/084898 discloses a torsion member by 3DQ.
  • the main purpose of the present specification is to provide a technique such as 3DQ that can prevent or suppress fatigue failure of a member manufactured by a technique of performing bending deformation in the hot state and then quenching.
  • a heating step in which a steel material having an oxide film on the surface is heated rapidly to a temperature equal to or higher than the Ac3 transformation point of the steel material so that the position to be heated moves in the axial direction of the steel material;
  • a quenching step of cooling and quenching a position close to a position to be heated by the heating step, so that a high temperature portion generated in the steel material becomes local;
  • a deformation step of bending the high temperature portion by applying a bending moment to the local high temperature portion moving in the axial direction of the steel material generated by the heating step and the quenching step;
  • a method for producing a hardened steel material is provided.
  • FIG. 1 is a schematic configuration diagram for explaining a hardened steel manufacturing apparatus according to a preferred embodiment of the present disclosure.
  • FIG. 2 is an overall view of the steel pipe showing the bending shapes and crack observation positions of the steel pipes in Examples 1, 2, and 3 and Comparative Examples 1 and 2.
  • FIG. 3 is a cross-sectional view showing the cross-sectional shape of the steel pipe and the hardness measurement position in Examples 1, 2, and 3 and Comparative Examples 1 and 2.
  • FIG. 4 is a graph illustrating an example of a measurement result of hardness in Example 1.
  • FIG. 5 is a graph showing an example of the measurement result of hardness in Example 3.
  • the fatigue fracture surface of a member manufactured by 3DQ is a grain boundary fracture surface, and Cu exists on the fracture surface.
  • fatigue failure often occurs outside the bending of a bent member. From this, the present inventors considered the reason why fatigue fracture occurs as follows.
  • 3DQ is the following method. While feeding the steel material, the induction heating device locally heats the steel material to the Ac3 transformation point or higher, and the steel material is rapidly quenched by the cooling device on the downstream side in the steel feed direction from the induction heating device. In the steel material between the induction heating device and the cooling device, a high temperature portion having a temperature equal to or higher than the local Ac3 transformation point is generated. By applying a bending moment to the high-temperature part, the steel material is hot-bent and is quenched and fixed in shape by cooling with a cooling device.
  • welded steel pipes which are steel materials used for 3DQ, are hot-rolled, pickled to remove the oxide film on the surface, slit (width cut) according to the diameter of the steel pipe, rounded ends It is manufactured by welding (tube making).
  • the reason why the oxide film on the surface is removed is that it is an obstacle to painting to ensure corrosion resistance.
  • the steel material that has undergone fatigue destruction is rapidly heated to 1000 ° C. or higher (for example, a heating rate of 800 ° C./sec) by using an induction heating device of a welded steel pipe (so-called white skin steel pipe) that has been piped through this pickling process. It was manufactured.
  • the reason for rapid heating is that the processing accuracy is better if the region softened at a high temperature of the steel material is narrowed.
  • the Ac3 transformation point of the steel material is approximately 800 to 900 ° C. depending on its composition.
  • the distribution of carbides in the original steel material is not uniform, so C (carbon) is not uniformly dispersed, and the hardness after quenching is not stable.
  • heating at 1000 ° C. or higher is preferable in the case of rapid heating.
  • the heating temperature is lowered to avoid melting of Cu, the hardness after quenching will be hindered.
  • the heating area is lowered and the heating area is widened so as to disperse C even at a low temperature at which Cu melting is avoided, the width of the softened area (width in the steel material feed direction) becomes wide, which hinders processing accuracy. Lowering the heating speed and lowering the moving speed of the heating position will hinder productivity. That is, it is not possible to solve all of the hardness and processing accuracy, productivity and avoidance of fatigue fracture after quenching only by changing the hot bending quenching conditions (heating temperature and heating rate).
  • the oxide film does not adhere to the welded part of the welded steel pipe due to bead removal.
  • Cu adheres to a portion where no oxide film is attached, and if tensile stress is applied, grain boundary cracking may occur. It was considered desirable to prevent the welded portion of the welded steel pipe from being located outside the
  • the present inventors thought that if it is necessary to remove the oxide film from the surface of the 3DQ processed product, the oxide film may be removed by pickling or shot blasting after the 3DQ processing.
  • the present inventors can increase the heating temperature by rapid heating during hot bending if it can remove or detoxify Cu adhering to the steel before bending that applies a bending moment to the steel. Even if it did, Cu did not reach the crystal grain boundary, and it was thought that all of the hardness, processing accuracy, and fatigue fracture avoidance after quenching could be achieved.
  • the detoxification method is to heat a steel material and hot-bend the material with an oxide film formed on the surface of the steel material. Cu adhering to the surface of the steel material is taken into the oxide film, and contact with the steel under the oxide film during hot bending is avoided.
  • the metal for example, Zn which is easy to evaporate in Cu alloy is evaporated by heating, the ratio of Cu in Cu alloy is raised, and melting
  • the method of manufacturing a hardened steel material according to the first embodiment includes locally inductively heating a steel material, locally deforming a high-temperature portion that is locally induction-heated, and then locally deforming the steel material.
  • the part thus formed is continuously quenched (cooled) and transformed into martensite.
  • the steel material is partially rapidly heated so that the heating position moves in the axial direction of the steel material, and the position adjacent to the heating position is cooled and quenched. Since a local high temperature part is generated in the steel material by heating and cooling at this time, a bending moment is applied to the local high temperature part to bend and deform the high temperature part.
  • Heating is performed by induction heating.
  • induction heating is adopted because a higher heating rate is better.
  • the steel material is locally heated by induction heating, and the position of the portion to be locally induction heated is continuously moved while the cooling position is also adjusted to the induction heating.
  • the induction heating device may be moved relative to the steel material, or the steel material may be moved relative to the induction heating device.
  • the heating temperature is equal to or higher than the Ac3 transformation point represented by the following empirical formula (1) with respect to the component amount of each element.
  • Ac3 910 ⁇ 203 ⁇ ⁇ C ⁇ 15.2 ⁇ Ni + 44.7 ⁇ Si + 104 ⁇ V + 31.5 ⁇ Mo ⁇ 30 ⁇ Mn ⁇ 11 ⁇ Cr ⁇ 20 ⁇ Cu + 700 ⁇ P + 400 ⁇ Al + 50 ⁇ Ti (1)
  • the time from when the locally induction-heated portion of the steel material reaches the Ac3 transformation point to when quenching cooling is performed is 0.2 seconds or more in order to achieve stable austenite, from the viewpoint of productivity. Is preferably 1.0 second or less.
  • the hot deformation and quenching technology is a technology that performs deformation such as bending, twisting, and shearing in the hot state, and then quenching, so that a mold or the like is not required. Due to induction heating and cooling from the outside of the steel material, heating and cooling are performed on and near the surface of the steel material. Therefore, when processing a steel material that is somewhat thick, such as for automotive parts, a steel material having a steel pipe shape is used. Among these, the steel material of a welded steel pipe is used suitably as a raw material for hot deformation hardening. This is because of cost (steel pipe price) and dimensional accuracy (thickness of the steel pipe is uniform).
  • the steel material used as the material is a steel material having an oxide film on the surface.
  • the steel material having an oxide film on the surface is preferably a welded steel pipe that has been piped while leaving the oxide film produced in the hot rolling process, that is, a welded steel pipe that has been piped without a pickling process after the hot rolling process.
  • a welded steel pipe in which the welded portion is linearly formed in the axial direction of the welded steel pipe is preferable.
  • the steel material used as the material is preferably one from which the weld bead generated in the welded portion of the welded steel pipe is removed.
  • the oxide film does not adhere to the welded portion of the welded steel pipe due to the bead removal.
  • Cu adheres to a portion where no oxide film is attached and a tensile stress is applied, which may cause grain boundary cracking. Therefore, when making the steel material used as a raw material a welded steel pipe from which beads are removed, it is preferable to bend and deform so that tensile stress is not applied to the welded portion.
  • a welded steel pipe as a raw material in a 3DQ apparatus to be described later so that the welded portion is disposed at a position where tensile stress is not applied (that is, other than the outside of the bending). That is, in 3DQ processing, it is preferable that the welded portion of the welded steel pipe is positioned on the bending inner side with respect to the bending neutral axis.
  • the steel material used as a material may be a steel pipe having a cross-sectional shape other than a circular shape, that is, a so-called deformed pipe.
  • the steel pipe formed into a circular cross-section by welding may be further deformed, and a steel pipe molded so that the cross-sectional shape becomes a shape other than a circle (for example, a flat shape or a rectangle) may be used as a material.
  • mold it is preferable to shape
  • the oxide film from the 3DQ processed product it may be removed by pickling or shot blasting after the 3DQ processing.
  • the method of manufacturing a hardened steel material according to the second embodiment includes an oxide film generation step for generating an oxide film on the surface of the steel material, and hot bending quenching (3DQ processing) of the steel material on which the oxide film is generated by the oxide film generation step. ) Hot bending quenching step.
  • the latter hot bending quenching step is the same as the method of manufacturing a hardened steel material described in the first embodiment, and therefore only a brief description will be given.
  • the steel material is locally induction-heated, and the locally hot-heated portion is locally deformed and then continuously deformed continuously. Then, it is quenched (cooled) and transformed into martensite.
  • the steel material is partially rapidly heated so that the heating position moves in the axial direction of the steel material, and the position adjacent to the heating position is cooled and quenched. Since a local high temperature part is generated in the steel material by heating and cooling at this time, a bending moment is applied to the local high temperature part to bend and deform the high temperature part.
  • generation process is a process of producing
  • an oxide film is generated on the surface of the steel material by heating the steel material. Heating is performed in an atmosphere containing oxygen, for example, in an air atmosphere.
  • the heating temperature is preferably at least the Ac3 transformation point, and the heating time is preferably within 10 seconds to 60 minutes.
  • the heating time here is a time during which a heating state at a predetermined temperature or higher continues.
  • the heating time is preferably within 60 minutes.
  • the means / device used for heating is not particularly limited.
  • the gas may be burned and furnace heated, induction heated, or energized heated.
  • You may use 3DQ apparatus (hardened steel manufacturing apparatus 10 demonstrated later) used for a hot bending quenching process.
  • heating using the 3DQ apparatus is performed by the induction heating apparatus of the 3DQ apparatus.
  • the induction heating device can only partially heat the steel material, but the entire steel material can be heated by relatively moving the induction heating device and the steel material so that the position of partial heating moves. At this time, bending by the 3DQ apparatus is not performed.
  • the heating furnace may be a batch furnace or a continuous furnace. Further, a gas furnace, a heavy oil furnace, an electric furnace, an infrared furnace, or the like can be used.
  • the material used for the oxide film generation process may be a welded steel pipe that has been piped through a pickling process after the hot rolling process, that is, a white steel pipe.
  • generation process may be the welded steel pipe (black skin steel pipe) pipe-formed without passing through the pickling process after a hot rolling process. Even if it is any welded steel pipe, an oxide film produces
  • an oxide film from a workpiece that has been subjected to hot bending quenching (3DQ processing) after generating an oxide film it may be removed by pickling or shot blasting after 3DQ processing.
  • the hardened steel material manufacturing apparatus 10 of the embodiment includes a hot deformation quenching section 12, a moving device 21, a guide 40, and a deforming force applying device 71.
  • the hot deformation quenching unit 12 includes a high-frequency induction heating device 52 and a water cooling device 54.
  • the high frequency induction heating device 52 is arranged on the upstream side in the steel material moving direction 2
  • the cooling device 54 is arranged on the downstream side in the steel material moving direction 2.
  • the high frequency induction heating device 52 includes an induction heating coil 51 and a high frequency power supply 55 that supplies high frequency power to the induction heating coil 51.
  • High frequency power is supplied from the high frequency power supply 55 to the induction heating coil 51, and an induction current is locally generated in the portion 61 of the steel material 1 inside the induction heating coil 51 to locally induction heat the portion 61 of the steel material 1.
  • the cooling device 54 includes a nozzle 53 and a cooling water supply unit 57 that supplies cooling water to the nozzle 53.
  • the cooling water supplied from the cooling water supply unit 57 is sprayed onto the steel material 1 by the nozzle 53, and the heated steel material 1 is rapidly cooled to quench the steel material 1.
  • the deformation force imparting device 71 retains the downstream portion of the steel material moving direction 2 with respect to the nozzle 53 of the steel material 1 by the retaining portion 72 of the deformation force imparting device 71.
  • a chuck is preferably used as the holding unit 72.
  • a manipulator is preferably used as the deforming force applying device 71.
  • a movable roller die is also preferably used.
  • the deforming force applying device 71 the heated high-temperature portion 63 is locally applied between the portion 61 that is locally induction-heated by the induction heating coil 51 and the portion 65 that is rapidly cooled by being sprayed with cooling water by the nozzle 53. Deformation force is applied.
  • the deformation force includes a bending moment, and in some cases, a torsional force or a shearing force is applied.
  • the guide 40 is provided in the vicinity of the induction heating coil 51 on the upstream side in the steel material moving direction 2 with respect to the induction heating coil 51 of the hot deformation quenching unit 12.
  • the moving device 21 holds the upstream portion of the steel material 1 in the steel material moving direction 2 with the holding portion 23 of the moving device 21, and continues the long steel material 1 along its longitudinal direction (steel material moving direction 2). To move.
  • the induction heating coil 51 and the nozzle 53 are arranged in this order in the steel material moving direction 2. Since the moving device 21 continuously moves the steel material 1 along the steel material moving direction 2, the steel device 1 is moved in the order of the induction heating coil 51 and the nozzle 53. Further, by the continuous movement of the steel material 1 along the steel material movement direction 2, the deformation force is locally applied by the part 61 of the steel material 1 that is locally induction heated by the induction heating coil 51 and the deformation force applying device 71. The high temperature portion 63 of the steel material 1 and the portion 65 that is rapidly cooled by being sprayed with cooling water by the nozzle 53 also move continuously along the steel material movement direction 2.
  • the movement with respect to the induction heating coil 51 and the nozzle 53 of the steel material 1 by the moving apparatus 21 is relative, and the steel material 1 may be moved by fixing the induction heating coil 51 and the nozzle 53. And the induction heating coil 51 and the nozzle 53 may be moved.
  • an electric servo cylinder or a manipulator is preferably used as the moving device 21.
  • a chuck is preferably used as the holding unit 23.
  • Control device The moving device 21, the high frequency induction heating device 52, the water cooling device 54, and the deformation force applying device 71 are connected to the control device 100 and controlled by the control device 100.
  • the hot deformation quenching described above and below will be performed by the control device 100 controlling the moving device 21, the high frequency induction heating device 52, the water cooling device 54, and the deformation force applying device 71.
  • the steel material is Chemical composition is mass%, C: 0.12% to 0.60%, Si: 0.001% to 2.0%, Mn: 0.5% to 3.0%, P: 0.05% or less, S: 0.01% or less, sol. Al: 0.001% to 1.0%, N: 0.01% or less, B: 0.01% or less, The balance: Fe and impurities.
  • the chemical composition is in mass% instead of part of Fe, Ti: 0.001% or more and 0.05% or less, Nb: 0.001% or more and 0.05% or less, V: 0.02% to 0.5%, Cr: 0.02% to 0.5%, Mo: 0.02 to 0.5%, Cu: 0.02% to 1.0% and Ni: 0.02% to 1.0%, You may contain 1 type, or 2 or more types of elements chosen from the group which consists of.
  • the processing method according to the embodiment is a manufacturing method using so-called quenching in which heat treatment and processing history are controlled to obtain a high-strength and processed product whose structure has been transformed from an austenite phase to a hard phase such as martensite. Since the strength after quenching of the steel sheet is mainly determined by the C content that controls the hardness of the martensite phase, the C content is determined according to the required strength. In order to secure the target strength of 1200 MPa or more in the embodiment, the C content is preferably 0.12% or more. In order to stably obtain higher strength, the content is more preferably over 0.20%. When the C content exceeds 0.60%, the toughness after quenching deteriorates and the risk of causing brittle fracture increases. Therefore, the upper limit of the C content is preferably 0.60%, more preferably 0.50% or less.
  • Si is preferably in the mass% range of 0.001% to 2.0%.
  • Si is an element that has the effect of increasing the strength after quenching without degrading the ductility or improving the ductility in order to suppress the formation of carbides in the cooling process from the austenite phase to the low temperature transformation phase. is there. If the Si content is less than 0.001%, it is difficult to obtain the above effect. Therefore, the Si content is preferably 0.001% or more. Note that when the Si content is 0.05% or more, the ductility is further improved. Therefore, the Si content is more preferably 0.05% or more. On the other hand, if the Si content exceeds 2.0%, the effects of the above action are saturated and disadvantageous economically, and the surface properties are significantly deteriorated. Therefore, the Si content is preferably 2.0% or less. More preferably, it is 1.5% or less.
  • Mn is preferably in the range of 0.5% to 3.0% by mass.
  • Mn is an extremely effective element for enhancing the hardenability of the steel and ensuring the strength after quenching stably.
  • the Mn content is preferably 0.5% or more.
  • the Mn content is 1.0% or more, it is possible to ensure a tensile strength of 1350 MPa or more as the strength after quenching. For this reason, it is more preferable that the Mn content is 1.0% or more.
  • the Mn content is preferably 3.0% or less. From the viewpoint of alloy cost and the like, the Mn content is more preferably 2.5% or less.
  • P is preferably 0.05% or less by mass.
  • P is an impurity inevitably contained in steel, but it may be positively incorporated because it has the effect of increasing strength by solid solution strengthening.
  • the P content exceeds 0.05%, the resistance weldability between the member of the present invention and the other member is significantly deteriorated.
  • the risk of brittle fracture increases when the strength is increased to 2500 MPa or more. Therefore, the P content is preferably 0.05% or less.
  • the P content is more preferably 0.02% or less. In order to obtain the above action more reliably, the P content is preferably set to 0.003% or more.
  • S is preferably 0.01% or less by mass.
  • S is an impurity inevitably contained in the steel, and is combined with Mn and Ti to produce sulfide and precipitate. If the amount of this precipitate increases excessively, the interface between the precipitate and the main phase may become the starting point of fracture, so the lower the content, the better. If the S content exceeds 0.01%, the adverse effect becomes significant. Therefore, the S content is preferably 0.01% or less. More preferably, it is 0.003% or less, More preferably, it is 0.0015% or less.
  • Al is preferably in the range of 0.001% to 1.0% or less.
  • Al is an element having an action of deoxidizing steel to make the steel material sound, and is also an element having an action of improving the yield of carbonitride forming elements such as Ti. sol. If the Al content is less than 0.001%, it is difficult to obtain the above effect. Therefore, sol.
  • the Al content is preferably 0.001% or more. More preferably, it is 0.015% or more. On the other hand, sol. If the Al content exceeds 1.0%, the weldability is significantly lowered and the oxide inclusions are increased, so that the surface properties are remarkably deteriorated. Therefore, sol.
  • the Al content is preferably 1.0% or less. More preferably, it is 0.080% or less.
  • N is preferably 0.01% or less by mass.
  • N is an impurity inevitably contained in the steel, and is preferably as low as possible from the viewpoint of weldability. If the N content exceeds 0.01%, the weldability is significantly reduced. Therefore, the N content is preferably 0.01% or less. More preferably, it is 0.006% or less.
  • B is preferably 0.01% or less by mass.
  • B is an element having an effect of increasing low temperature toughness. Therefore, B may be contained. However, if the content exceeds 0.01%, the hot workability deteriorates and hot rolling becomes difficult. Therefore, the B content is preferably 0.01% or less. In addition, in order to acquire the effect by the said action more reliably, it is preferable to make B content 0.0003% or more.
  • Example 1 The inventors of the present invention have provided a raw pipe (so-called black skin steel pipe) that has been piped without undergoing a pickling process after the hot rolling process, and a raw pipe that has been piped through the pickling process after the hot rolling process ( Using so-called white skin steel pipe), bending was performed with a 3DQ apparatus, and the influence of the presence or absence of the pickling step before bending on the surface crack and hardenability of the 3DQ processed product was investigated. Note that the structure of the 3DQ base pipe was ferrite-pearlite in order to ensure workability when pipe-making from a steel plate.
  • the specific conditions of the steel material (element tube) used for 3DQ processing are shown below.
  • the composition of the raw tube was the chemical composition shown in Table 1.
  • the raw tube was a flat tube having the cross-sectional shape shown in FIG.
  • the dimension W in the width direction shown in this figure is 45 mm, and the dimension H in the height direction is 13 mm.
  • the plate thickness is 2.8 mm.
  • the thickness of the oxide film on the raw tube surface is 10 ⁇ m. In order to avoid cracking, a thicker oxide film is desirable. In order to increase the thickness of the oxide film, the hot rolling finishing temperature may be increased.
  • Cu-Zn (hexa brass) powder was adhered to the surface of each element tube, and then bending was performed using a 3DQ apparatus.
  • the heating temperature by induction heating was set to three conditions of 900 ° C., 950 ° C., and 1030 ° C.
  • bending is performed within the flat surface of the flat tube (in other words, bending so that the neutral axis is oriented in the longitudinal direction of FIG. 3), and the bending radius is 95 mm.
  • the reason why the tube is bent in the flat plane is that if the tube is bent in the flat plane, a large tensile stress is generated on the outside of the bend and the problem of cracking is likely to be manifested.
  • Vickers hardness was measured with a load of 5 kgf to evaluate the presence or absence of quenching.
  • Vickers hardness of 470 or higher was determined to be quenched, and Vickers hardness of less than 470 was determined to be not quenched.
  • the four locations in the circumferential direction are the center positions P1 and P3 of the pair of long side portions of the flat tube and the center positions P2 and P4 of the pair of short side portions connecting the pair of long side portions.
  • the three locations in the plate thickness direction are a position 0.5 mm from the outer surface, a position in the center of the plate thickness, and a position 0.5 mm from the inner surface.
  • Table 2 summarizes the evaluation results.
  • A represents that there is no crack
  • B represents that there is a crack in some samples
  • C represents that there is a crack in all samples.
  • A represents quenching and B represents no quenching.
  • FIG. 4 is an example of the hardness measurement result in Example 1.
  • the use of a steel pipe (black skin steel pipe) with an oxide coating on the surface as a raw pipe can suppress the occurrence of surface cracks while ensuring stable hardenability by 3DQ processing.
  • the method for manufacturing a hardened steel material according to the present disclosure is particularly suitable for manufacturing an undercarriage part of an automobile such as a suspension arm.
  • Example 2 and Example 3 Furthermore, the present inventors used a white skin steel pipe as a raw material (element pipe), and performed bending by the following three methods (Comparative Example 2, Example 2 and Example 3).
  • the method of Comparative Example 2 is a method in which pre-heat treatment (oxide film generation step) is not performed before bending by a 3DQ apparatus.
  • the method of Example 2 is a method of performing heat treatment (in the air atmosphere, heating temperature 1030 ° C., heating time 17 seconds) without bending by the same 3DQ device before bending by the 3DQ device.
  • the raw tube is placed in a heating furnace and subjected to a long-time heat treatment (in air atmosphere, heating temperature 1000 ° C., heating time 2.5 minutes to 10 minutes) before bending by the 3DQ apparatus. Is the method.
  • the specific conditions of the steel material (element tube) used for 3DQ processing are shown below.
  • the composition of the raw tube was the chemical composition shown in Table 3.
  • the raw tube was a flat tube having the cross-sectional shape shown in FIG.
  • the dimension W in the width direction shown in this figure is 45 mm, and the dimension H in the height direction is 13 mm.
  • the plate thickness is 2.8 mm.
  • the heating temperature by induction heating was set to three conditions of 900 ° C., 950 ° C., and 1030 ° C.
  • bending is performed within the flat surface of the flat tube (in other words, bending so that the neutral axis is oriented in the longitudinal direction of FIG. 3), and the bending radius is 95 mm.
  • the reason why the tube is bent in the flat plane is that if the tube is bent in the flat plane, a large tensile stress is generated on the outside of the bend and the problem of cracking is likely to be manifested.
  • Vickers hardness was measured with a load of 5 kgf to evaluate the presence or absence of quenching.
  • Vickers hardness of 470 or higher was determined to be quenched, and Vickers hardness of less than 470 was determined to be not quenched.
  • the four locations in the circumferential direction are the center positions P1 and P3 of the pair of long side portions of the flat tube and the center positions P2 and P4 of the pair of short side portions connecting the pair of long side portions.
  • the three locations in the plate thickness direction are a position 0.5 mm from the outer surface, a position in the center of the plate thickness, and a position 0.5 mm from the inner surface.
  • Table 4 summarizes the evaluation results. As for the presence or absence of cracks, A was not cracked in all samples, B was cracked in some samples, but the occurrence frequency of cracks was less than 50%, and the occurrence frequency of cracks was 50% or more. Represents. As for the presence or absence of quenching, A represents quenching and B represents no quenching.
  • Example 3 when pre-heat treatment was performed in the heating furnace (Example 3), the number of samples with surface cracks decreased compared to Example 2 even when the pre-heat treatment time was 2.5 minutes. It was.
  • the scale thickness after the pre-heat treatment was 11 ⁇ m.
  • the heating time was 5 minutes, surface cracks did not exist under the conditions of 900 ° C. and 950 ° C., and the number of samples with surface cracks under 1030 ° C. was less than 50%.
  • the scale thickness after the pre-heat treatment was 36 ⁇ m.
  • FIG. 4 is an example of a measurement result of hardness in Example 3 (heating time 10 minutes).
  • the method for manufacturing a hardened steel material according to the present disclosure is particularly suitable for manufacturing an undercarriage part of an automobile such as a suspension arm.
  • a heating step in which a steel material having an oxide film on the surface is heated rapidly to a temperature equal to or higher than the Ac3 transformation point of the steel material so that the position to be heated moves in the axial direction of the steel material;
  • a quenching step of cooling and quenching a position close to a position to be heated by the heating step, so that a high temperature portion generated in the steel material becomes local;
  • a deformation step of bending the high temperature portion by applying a bending moment to the local high temperature portion moving in the axial direction of the steel material generated by the heating step and the quenching step;
  • a method for manufacturing a hardened steel material A method for manufacturing a hardened steel material.
  • the steel material is a welded steel pipe, The method for producing a hardened steel material according to [1].
  • the welded portion of the welded steel pipe is not located outside the bending deformation.
  • the welded portion of the welded steel pipe is located on the inside of the bend from the neutral axis of the bend;
  • the oxide film is an oxide film generated in a hot rolling process, [1] The method for producing a hardened steel material according to any one of [4].
  • [6] The oxide film has an average thickness of 10 ⁇ m or more. [1] The method for producing a quenched steel material according to any one of [5].
  • the oxide film generation step includes The heating temperature is not less than the Ac3 transformation point, and the heating time at the Ac3 transformation point or more is 10 seconds or more.
  • the oxide film generation step includes The heating time above the Ac3 transformation point is 5 minutes or more, [8] The method for producing a quenched steel material according to [8].
  • the oxide film generation step is performed by heating a steel material in a heating furnace.
  • the oxide film generation step is performed by heating a welded steel pipe.
  • the thickness of the oxide film produced in the oxide film production step is 36 ⁇ m or more,
  • the temperature above the Ac3 transformation point in the heating step is 900 to 1030 ° C., [7] The method for producing a quenched steel material according to any one of [12] to [12].
  • a heating step in which a steel material having an oxide film on the surface is heated rapidly to a temperature equal to or higher than the Ac3 transformation point so that the position to be heated moves in the axial direction of the steel material;
  • a quenching step of cooling and quenching a position close to a position to be heated by the heating step, so that a high temperature portion generated in the steel material becomes local;
  • a deformation step of bending the high temperature portion by applying a bending moment to the local high temperature portion moving in the axial direction of the steel material generated by the heating step and the quenching step;
  • a method for manufacturing a hardened steel material A method for manufacturing a hardened steel material.
  • the steel material is a welded steel pipe, The manufacturing method of the hardened steel materials as described in (1).
  • the welded portion of the welded steel pipe is not located outside the bending deformation.
  • the welded portion of the welded steel pipe is located on the inside of the bend from the neutral axis of the bend;
  • the oxide film is an oxide film generated in a hot rolling process, (1) The method for producing a hardened steel material according to any one of (4).
  • the oxide film has an average thickness of 10 ⁇ m or more.
  • ⁇ 1> An oxide film generation step of heating the steel material to generate an oxide film on the surface of the steel material; A heating process in which the steel material having an oxide film formed on the surface by the oxide film generation process is partially heated rapidly to a temperature equal to or higher than the Ac3 transformation point so that the heating position moves in the axial direction of the steel material; A quenching step of cooling and quenching a position close to a position to be heated by the heating step, so that a high temperature portion generated in the steel material becomes local; A deformation step of bending the high temperature portion by applying a bending moment to the local high temperature portion moving in the axial direction of the steel material generated by the heating step and the quenching step; A method for manufacturing a hardened steel material.
  • the oxide film generation step includes The heating temperature is not less than the Ac3 transformation point, and the heating time at the Ac3 transformation point or more is not less than 10 seconds.
  • the oxide film generation step includes The heating time above the Ac3 transformation point is 5 minutes or more,
  • the oxide film generation step is performed by heating a steel material in a heating furnace. ⁇ 1>- ⁇ 3> The manufacturing method of the hardened steel materials as described in any one of.
  • the oxide film generation step includes Done by heating the welded steel pipe, The method for producing a quenched steel material according to any one of ⁇ 1> to ⁇ 4>.
  • ⁇ 6> The method for producing a quenched steel material according to any one of ⁇ 1> to ⁇ 5>, wherein a thickness of the oxide film generated in the oxide film generation step is 36 ⁇ m or more.
  • ⁇ 7> The temperature above the Ac3 transformation point in the heating step is 900 to 1030 ° C., ⁇ 1>- ⁇ 6> The method for producing a quenched steel material according to any one of ⁇ 6>.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Articles (AREA)
  • Bending Of Plates, Rods, And Pipes (AREA)

Abstract

La présente invention concerne un procédé permettant la fabrication d'un matériau en acier trempé qui, dans un mode de réalisation, comprend : une étape de chauffage dans laquelle un matériau en acier ayant un film d'oxyde sur sa surface est chauffé partiellement de façon telle qu'une position à chauffer se déplace dans la direction axiale du matériau en acier et est chauffée rapidement pour atteindre ou dépasser une température d'un point de transformation Ac3 du matériau en acier ; une étape de trempe dans laquelle une position près de la position à chauffer par l'étape de chauffage est refroidie et trempée de sorte qu'une partie à haute température qui est produite dans le matériau en acier vienne à être localisée ; et une étape de déformation dans laquelle un moment de cintrage est appliqué à la partie à haute température localisée qui a été produite par l'étape de chauffage et l'étape de trempe et qui se déplace dans la direction axiale du matériau en acier de manière à cintrer et déformer la partie à haute température.
PCT/JP2017/008622 2016-03-09 2017-03-03 Procédé permettant la fabrication de matériau en acier trempé WO2017154796A1 (fr)

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JP2016045672 2016-03-09
JP2016-045672 2016-03-09
JP2016045671 2016-03-09
JP2016-045671 2016-03-09
JP2017-028375 2017-02-17
JP2017028375A JP6210172B2 (ja) 2016-03-09 2017-02-17 焼入れ鋼材の製造方法
JP2017028374A JP6210171B2 (ja) 2016-03-09 2017-02-17 焼入れ鋼材の製造方法
JP2017-028374 2017-02-17

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108906941A (zh) * 2018-08-28 2018-11-30 南京航威智造科技有限公司 一种基于串并联机器人的三维复杂构件成形系统及方法

Citations (6)

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Publication number Priority date Publication date Assignee Title
JPH0259103A (ja) * 1988-08-24 1990-02-28 Sumitomo Metal Ind Ltd 曲げ加工用熱延鋼板の製造法
WO2006093006A1 (fr) * 2005-03-03 2006-09-08 Sumitomo Metal Industries, Ltd. Procédé de traitement de cintrage pour matériau de métal, appareil de traitement de cintrage, ligne d’équipement de traitement de cintrage et produit cintré obtenu ainsi
WO2010050460A1 (fr) * 2008-10-28 2010-05-06 住友金属工業株式会社 Procédé et dispositif de fabrication d’un produit coudé
WO2011007810A1 (fr) * 2009-07-14 2011-01-20 住友金属工業株式会社 Dispositif et procédé de fabrication d'un élément courbé
JP2012132098A (ja) * 2010-12-01 2012-07-12 Sumitomo Metal Ind Ltd 亜鉛系めっき熱処理鋼材およびその製造方法
JP2014100732A (ja) * 2012-11-21 2014-06-05 Toyo Seat Co Ltd パイプ成形装置

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0259103A (ja) * 1988-08-24 1990-02-28 Sumitomo Metal Ind Ltd 曲げ加工用熱延鋼板の製造法
WO2006093006A1 (fr) * 2005-03-03 2006-09-08 Sumitomo Metal Industries, Ltd. Procédé de traitement de cintrage pour matériau de métal, appareil de traitement de cintrage, ligne d’équipement de traitement de cintrage et produit cintré obtenu ainsi
WO2010050460A1 (fr) * 2008-10-28 2010-05-06 住友金属工業株式会社 Procédé et dispositif de fabrication d’un produit coudé
WO2011007810A1 (fr) * 2009-07-14 2011-01-20 住友金属工業株式会社 Dispositif et procédé de fabrication d'un élément courbé
JP2012132098A (ja) * 2010-12-01 2012-07-12 Sumitomo Metal Ind Ltd 亜鉛系めっき熱処理鋼材およびその製造方法
JP2014100732A (ja) * 2012-11-21 2014-06-05 Toyo Seat Co Ltd パイプ成形装置

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108906941A (zh) * 2018-08-28 2018-11-30 南京航威智造科技有限公司 一种基于串并联机器人的三维复杂构件成形系统及方法

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