JP2015025156A - Method of producing steel member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing a steel member which carries out hardening in a short time with high controllability to some parts of a carbon steel material.SOLUTION: A laser heating part for heating a carbon steel material by irradiating with a laser beam and a water cooling part for cooling the carbon steel material by bringing water in contact with the carbon steel material are arranged side by side, and a carbon steel material is moved relative to the laser heating part and the water cooling part. A part of the carbon steel material is irradiated with a laser beam in the laser heating part and then brought into contact with water in the water cooling part. The width of the water cooling part is preferably wider than that of the laser heating part, and the distance between the laser heating part and the water cooling part is preferably equal to ro smaller than the length of the laser heating part.

Description

  The present invention relates to a method for manufacturing a steel member, and more particularly to a method for manufacturing a steel member in which a part of a carbon steel material is quenched.

  In steel members that require high mechanical strength, such as parts mounted on vehicles such as seats, the strength of the steel material itself can be increased in order to increase the strength. Conventionally, it has been generally performed to improve the strength by heating the entire member with a flame or the like and quenching. However, in recent years, only a part of the member is quenched to improve the strength. For example, in Patent Document 1, it is intended to improve the material strength by subjecting the formed steel to heat treatment locally or entirely by high-frequency induction heating and then cooling it.

Special table 2013-510044 gazette

  When performing high-frequency induction heating, a part of the object can be selectively heated to some extent by devising the shape of the high-frequency induction coil to be used. However, it is difficult to precisely control the heating conditions such as the heating area and the distribution of the heating temperature. Moreover, since high frequency induction heating is internal heating based on the principle of heat generation of the material to be heated, the heating temperature and its spatial distribution are likely to depend on the shape of the material. Due to these factors, it is difficult to perform heating while controlling so as to obtain desired mechanical properties (hardness, toughness, etc.) for a minute region in a metal material using high frequency induction heating. is there.

  Moreover, due to the fact that high-frequency induction heating is based on internal heating, it takes a long time to heat an object to a desired temperature by high-frequency induction heating, and it is difficult to increase the processing speed. For example, in the case of continuously performing quenching while moving a carbon steel plate having a thickness of 1.0 to 1.2 mm with respect to the high frequency induction coil, in order to heat to about 910 ° C. necessary for obtaining the quenching effect The moving speed of the steel sheet typically needs to be 12 mm / second or less.

  The problem to be solved by the present invention is to provide a method for producing a steel member that can quench a part of a carbon steel material with high controllability and in a short time.

  In order to solve the above problems, a method for producing a steel member according to the present invention includes a laser heating unit that irradiates and heats a carbon steel material with laser light, and a water cooling unit that cools the carbon steel material by bringing water into contact therewith. The carbon steel material is irradiated with laser light at the laser heating part while moving the carbon steel material relative to the laser heating part and the water cooling part, and then the water cooling is performed. The point is to bring water into contact with the part.

  Here, it is preferable that the width of the water cooling part along the direction intersecting the direction of relative movement of the carbon steel material is wider than the width of the laser heating part.

  The distance between the laser heating unit and the water cooling unit along the direction of relative movement of the carbon steel material is less than or equal to the length of the laser heating unit along the direction of relative movement of the carbon steel material. There should be.

  And before the said carbon steel material receives irradiation of a laser beam by the said laser heating part, it is preferable to receive irradiation of the laser beam whose energy density is lower than the said laser heating part in a preheating part.

  According to the method for producing a steel member according to the invention, in the laser heating part, since a part of the carbon steel material is heated using laser light, with high spatial uniformity for a desired minute region, Heating can be performed while controlling the heating conditions. And since the site | part heated in the laser heating part is cooled by a water-cooling part, a fine metal structure can be formed in the site | part, and it can have high strength, hardness, and toughness in balance. Thereby, the steel member by which local hardening was given can be manufactured, controlling mechanical characteristics, such as intensity | strength, hardness, and toughness. Moreover, by using a laser beam, heating to a temperature required for quenching can be performed in a short time, and quenching can be completed in a short time.

  Here, when the width of the water cooling section along the direction intersecting the direction of relative movement of the carbon steel material is wider than the width of the laser heating section, Can be cooled to.

  In addition, when the distance between the laser heating unit and the water cooling unit along the direction of relative movement of the carbon steel material is equal to or less than the length of the laser heating unit along the direction of relative movement of the carbon steel material, Since the part heated by laser irradiation can be rapidly cooled, the coarsening of the quenched structure can be suppressed and the toughness of the carbon steel can be maintained high. In addition, the diffusion of heat to the surrounding parts can be kept small.

  When the carbon steel material is irradiated with laser light having an energy density lower than that of the laser heating part in the preheating part before being irradiated with the laser light by the laser heating part, Quenching can be performed with high efficiency by heating the carbon steel and further heating with the laser heating unit.

It is a schematic diagram which shows the manufacturing method of the steel member concerning one Embodiment of this invention, (a) is a perspective view, (b) is a top view. It is a perspective view which shows an example of the side frame of the vehicle seat which gave partial hardening by the said manufacturing method. It is a figure which shows an example of the slide rail of the vehicle seat which gave partial hardening by the said manufacturing method, (a) is a perspective view, (b) is AA sectional drawing. It is a top view which shows the shape of the test piece used for evaluation of tensile strength and elongation. It is a SEM image of the surface of the carbon steel material which performed partial hardening, (a) is Example 1, (b) is Example 2, (c) is a thing of the comparative example 1. FIG.

  Hereinafter, the manufacturing method of the steel member concerning one embodiment of the present invention is explained, referring to drawings.

<Method of partial quenching>
In this manufacturing method, a part of a carbon steel material is partially quenched to manufacture a steel member. FIG. 1 schematically shows this partial quenching method.

  As shown in FIG. 1 (a), the carbon steel material 10 that is a workpiece is partially quenched while being moved along the machining progress direction M. Partial quenching is performed using laser light 1 and cooling water 2. The laser beam 1 and the cooling water 2 are arranged side by side along the processing progress direction M of the carbon steel material 10. The laser beam 1 is disposed in front of the processing progress direction M, and the cooling water 2 is disposed behind. That is, the carbon steel material 10 that moves along the processing progress direction M comes into contact with the cooling water 2 after being irradiated with the laser beam 1. In the following, the front-rear direction is defined as the front-rear direction with respect to the machining progress direction M.

  The laser beam 1 is a region where the surface of the carbon steel material 10 is irradiated, the center position in the width direction of the laser irradiation unit 3 (a direction intersecting substantially perpendicular to the processing progress direction M), and the cooling water 2 is the carbon steel material 10. The position in the center in the width direction of the water-cooling unit 4 that is a region in contact with the surface is aligned. And the rear end part of the laser irradiation part 3 and the front end part of the water cooling part 4 are arrange | positioned in the position which only the predetermined distance d left | separated.

The laser irradiation unit 3 includes a laser heating unit 3A disposed at the rear and a preheating unit 3B disposed at the front. The laser heating unit 3A has a higher energy density than that of the preheating unit 3B and occupies a large area. In order to obtain a quenching effect, the laser heating unit 3 </ b> A has a sufficient austenite state for the irradiated portion of the carbon steel material 10 to have an energy density as high as possible. Specifically, it is preferable that the carbon steel material 10 can be heated to about 910 ° C. in a short time, and for example, it preferably has an energy density of 1775 W / cm ² or more. For example, when the width a1 of the laser heating unit 3A is 13 mm and the length b1 along the processing progress direction M is 10 mm, the output of the laser heating unit 3A is preferably 3 to 4 kW. The length b1 of the laser heating unit 3A is preferably long enough to obtain a sufficient quenching effect while one part of the carbon steel material 10 passes through the laser heating unit 3A. The energy density of the laser heating unit 3A However, when the energy density is as described above, the length b1 is preferably 10 mm or more.

  The type of the laser light source that forms the laser heating unit 3A is not particularly limited, but it is preferable to use a semiconductor laser as the laser that can obtain a high output as described above. In order to guide the laser beam 1 emitted from the laser light source to the surface of the carbon steel material 10 as the laser heating unit 3A having a predetermined size and shape, a laser processing head in which a plurality of optical lenses are combined is used. It is preferable.

  The preheating part 3B is not necessarily provided, but before heating the part of the carbon steel material 10 to such a high temperature that the quenching effect can be obtained by the laser heating part 3A, the part is reduced to a certain high temperature. It plays the role of preheating. Thus, after preheating in the preheating part 3B, by performing main heating in the laser heating part 3A, a higher heating effect can be obtained than in the case of performing main heating from room temperature. The quenching effect can be enhanced. It is preferable that the energy density of the preheating part 3B is 60 to 70% of the energy density of the laser heating part 3A. For example, when the width a2 of the preheating part 3B is 10 mm and the length b2 is 5 mm, the output of the preheating part 3B is preferably about 500 W. The length b2 of the preheating part 3B is preferably long enough to obtain a sufficient preheating effect, the energy density of the preheating part 3B is in the above range, and the length b1 of the laser heating part 3A is 10 mm. In the case of the above, it is preferably 5 mm or more. In order to increase the efficiency of preheating, it is preferable that the preheating unit 3B and the laser heating unit 3A are in contact with each other. However, if heat dissipation before the main heating of the heat given by the preheating unit 3B is not a problem, both An interval may be provided between them.

  The preheating unit 3B may be formed using the same type of laser light source as the laser heating unit 3A, or may be formed using a different type of light source. From the viewpoint of simplicity, it is preferable to form the preheating part 3B and the laser heating part 3A from the same type of laser light source. Furthermore, using a single laser light source, the energy density is distributed in a single beam spot. By forming, it is preferable to set it as the preheating part 3B and the laser heating part 3A. Such energy density distribution can be easily formed by using the laser processing head as described above.

  The water cooling unit 4 is cooled by bringing water into contact with the carbon steel material 10 heated in the laser heating unit 3 </ b> A, and forms a martensite state in the carbon steel material 10. The means for supplying water to the water-cooling unit 4 is cooled to such an extent that heating in the laser irradiation unit 3 is not hindered, and adhesion of water to the part of the carbon steel material 10 other than the part to be partially quenched is not a problem. Any material can be used as long as the water 2 can be brought into contact with the carbon steel material 10 locally. For example, the structure using a nozzle can be illustrated. The temperature of the cooling water 2 is preferably 25 to 30 ° C. Further, the width a3 of the water cooling unit 4 is preferably wider than the width a1 of the laser heating unit 3A. Although it is possible to perform heating locally by using a laser, there is a possibility that a wider range than the laser irradiation unit 3 may be affected by the heating, and the water-cooled unit covers a wider area than the laser irradiation unit 3. By cooling at 4, the thermal effect on the laser irradiation unit 3 and its peripheral region can be eliminated with high accuracy. Preferably, the width a3 of the water cooling unit 4 is preferably about 1.5 to 2 times the width a1 of the laser heating unit 3A.

  Furthermore, the portion of the carbon steel material 10 heated by the laser heating unit 3A is rapidly cooled by the water cooling unit 4 to form a fine metal structure of the carbon steel material 10 and toughness (elongation) of the carbon steel material 10. Can be kept high. In this sense, the distance d between the water cooling unit 4 and the laser heating unit 3A is preferably short, and as a guide, it is preferable that the distance d is equal to or less than the length b1 of the laser heating unit 3A. By shortening the distance d between the water cooling unit 4 and the laser heating unit 3A, there is also an effect that the thermal influence due to the diffusion of heat to the periphery of the part to be partially quenched can be suppressed.

  Using such a laser irradiation part 3 and a water cooling part 4, by continuously performing laser irradiation and water cooling while moving the carbon steel material 10 in the processing progress direction M, carbon is irradiated in the part that has been subjected to laser irradiation and water cooling. The steel material 10 is quenched. In FIG. 1, if the carbon steel material 10 is moved so that the entire quenching part 5 to be quenched is subjected to laser irradiation by the laser irradiation part 3 and water cooling in the water cooling part 4, The quenching portion 5 can be selectively hardened.

  In this way, the strength and hardness of the portion that has been quenched are increased compared to before the quenching. By applying such quenching to only a part of the carbon steel material 10, it is possible to obtain a steel member having improved strength and hardness only in that part. Furthermore, since the site | part which received the heating by laser irradiation receives water cooling immediately after being heated, the coarsening of the metal structure by heating is suppressed, Thereby, the toughness (elongation) of the carbon steel material 10 becomes a high value. Maintained.

  As shown in Patent Document 1, partial quenching in which a space is defined to some extent can also be performed by high frequency induction heating. However, since high frequency induction heating is based on the principle of internal heating, it is difficult to strictly control the heated part. On the other hand, in the case of using laser heating, the heating is performed by applying laser beam energy to the member to be heated, and by using an optical lens or the like, the beam spot is narrowed down and the beam shape is further reduced. Since it is easy to design in a desired shape, partial quenching can be performed while finely controlling the space for heating. In addition, the degree of quenching can be easily controlled by controlling the output intensity and irradiation time of the laser beam. With these features, it is possible to accurately limit the space for quenching, minimize the propagation of thermal effects to other parts, and control the hardness, toughness, and other characteristics of the quenched parts. It has become.

  In laser heating, in addition to the principle of external heating, the use of a high-intensity laser light source can shorten the time required for heating up to the required temperature. Quenching can be performed while moving a certain carbon steel material 10 at a high speed. The time required for the temperature rise depends on the shape of the carbon steel material 10 and the energy density of the laser beam 1, but, for example, the width a1 is 13 mm and the length with respect to a carbon steel plate having a plate thickness of 1.0 to 1.2 mm. When heating to 910 ° C. necessary for quenching using the laser heating unit 3A with b1 of 10 mm and output of 3 to 4 kW, the carbon steel material 10 is moved in the processing progress direction M at a speed of 25 mm / second or more. be able to.

  As described above, by performing partial quenching using laser light under well-controlled conditions, the strength can be increased by quenching selectively for a part that requires particularly high strength and hardness among certain members. And the hardness can be improved. For example, if some parts of a continuous steel member require high material strength but other parts do not require high material strength, the entire steel member should However, it is possible to improve the material strength only at the site by performing partial quenching using a laser beam only on a site where high material strength is required. In general, the higher the strength of carbon steel material, the higher the price. Therefore, it is required to form the entire steel member with a relatively low-strength material that is inexpensive and raise the material strength by quenching using only a necessary part. The material cost can be suppressed while satisfying the material strength.

  For example, with respect to SPC440 material (hardness: Hv150) which is a cold rolled material having a tensile strength of 440 MPa, or SPC590 material (hardness: Hv200) which is a cold rolled material having a tensile strength of 590 MPa, As described above, by performing partial quenching using a laser, strength and hardness corresponding to the SPC980 material (hardness: Hv300) having a tensile strength of 980 MPa can be obtained in some parts.

  The partial quenching using the laser beam as described above can be applied to any carbon steel material as long as the shape of the laser irradiation unit 3 and the water cooling unit 4 and the processing progress direction M are appropriately set. . As shown in FIG. 1, the plate-shaped carbon steel material may be partially quenched, and then the carbon steel material may be processed into a desired shape, or the carbon steel material processed into a desired shape may be partially Quenching may be performed. In general, since the material strength is lower, it is easier to perform mechanical processing such as press working and bending, so the latter method in which partial quenching is performed after processing is preferable from the viewpoint of facilitating processing.

  In addition, you may perform tempering suitably with the objective of the improvement of toughness etc. with respect to the site | part which performed partial hardening. In addition, heat treatment may be appropriately performed after partial quenching for the purpose of smoothly changing the characteristics between a site where partial quenching is performed and a surrounding site where partial quenching is not performed.

  Moreover, in the said embodiment, although the laser irradiation part 3 and the water cooling part 4 were fixed and the carbon steel material 10 was moved with respect to these, the carbon steel material 10 was fixed and the laser irradiation part 3 and the water cooling part 4 were moved. May be moved.

<Example of steel member to be partially quenched>
As described above, when it is desired to increase the material strength of only a part of a certain steel member, the partial quenching according to the above embodiment can be applied to various steel members. Below, the case of the member which comprises the vehicle seat is mentioned as an example.

(Side frame)
FIG. 2 shows a side frame 20 of a vehicle seat. The side frames 20 are members that are disposed on both sides in the width direction of the backrest portion of the seat and connect the backrest portion and the seating portion. In the entire side frame 20, only the front and rear end edges 21, 21 arranged at the front and rear of the vehicle in the traveling direction are partially quenched using laser light. In FIG. 2, the part to which partial hardening is given is shown by cross hatching.

  In the side frame 20, a particularly large load is applied to the front and rear end edges 21, 21 during the front collision and the rear collision, and stress concentrates on the front and rear end edges 21, 21. Therefore, by performing partial quenching on the front and rear edge portions 21 and 21, the strength and hardness of this portion can be improved, and even if stress is concentrated, the material can hardly be broken. As described above, if the entire side frame 20 is configured using the SPC440 material or the SPC590 material, and the strength and hardness of the front and rear edge portions 21 and 21 are improved to a level corresponding to the SPC980 material, the front and rear edge In both the parts 21 and 21 and other parts, it is possible to achieve strength and hardness that satisfy the requirements as a vehicle seat.

(Slide rail)
FIG. 3 shows a slide rail 30 for a vehicle seat. The slide rail 30 includes a long lower rail 31 and an upper rail 32. The lower rail 31 is fixed to the floor surface of the vehicle, and the seat body is fixed to the upper rail 32. When the upper rail 32 slides in the longitudinal direction with respect to the lower rail 31, the seat body can slide relative to the floor surface.

  The lower rail 31 is formed to have a substantially U-shaped cross section, and has inner bent portions 31b and 31b that are bent inward continuously to the rising surfaces 31a and 31a constituting the side surfaces. The upper rail 32 is also formed to have a substantially U-shaped cross section, and has outer bent portions 32b and 32b that are bent outward and continuous with the hanging surfaces 32a and 32a constituting the side surfaces. By inserting the outer bent portions 32b, 32b of the upper rail 32 between the rising surfaces 31a, 31a of the lower rail 31 and the inner bent portions 31b, 31b, the lower rail 31 and the upper rail 32 are engaged. A ball bearing can be accommodated in a region sandwiched between the inner surfaces of the rising surfaces 31a and 31a and the inner bent portions 31b and 31b of the lower rail 31 and the outer surfaces of the outer bent portions 32b and 32b of the upper rail 32. Upper sliding spaces 33a and 33a and lower sliding spaces 33b and 33b are formed. Ball bearings (not shown) are arranged in the upper sliding spaces 33a and 33a and the lower sliding spaces 33b and 33b so that the sliding between the lower rail 31 and the upper rail 32 is performed smoothly.

  Here, the portions facing the upper sliding spaces 33a and 33a and the lower sliding spaces 33b and 33b of the lower rail 31 and the upper rail 32, that is, the inside of the portion between the rising surfaces 31a and 31a and the bottom surface 31c in the lower rail 31, and Partial quenching using laser light is applied to the inside of the portion between the rising surfaces 31a, 31a and the inner bent-back portions 31b, 31b, and the portion of the upper rail 32 facing them. In FIG. 3, the site | part to which partial hardening is given is shown by cross hatching. In FIG. 3, for easy understanding, the parts to be partially quenched are shown in a raised shape, but actually these parts are continuous with the surrounding parts.

  Indentations from the ball bearings are likely to be formed at portions of the lower rail 31 and the upper rail 32 that come into contact with the ball bearings. However, as described above, the portions facing the upper sliding spaces 33a and 33a and the lower sliding spaces 33b and 33b that are in contact with the ball bearings are partially quenched, and the surfaces are hardened so that these portions are hardened. An indentation is hardly formed and a smooth surface can be maintained. Thereby, smooth sliding between the lower rail 31 and the upper rail 32 can be maintained over a long period of time. Also in this case, the entire lower rail 31 and upper rail 32 are formed using the SPC440 material or the SPC590 material, and the hardness of the specific portion facing the upper sliding spaces 33a and 33a and the lower sliding spaces 33b and 33b is set to SPC980. If it is improved to a level corresponding to the material, the hardness necessary for preventing the formation of indentation can be obtained at the contact portion with the ball bearing while enjoying the sufficient material strength as the entire slide rail.

  Hereinafter, the present invention will be described more specifically with reference to examples.

[Preparation of sample piece]
(Example)
An SPC440 material (plate thickness: 0.75 mm) having a hardness of Hv152 was cut into a 20 mm × 150 mm rectangle to obtain a steel plate piece. A laser beam having a power of 4 kW was formed into a 19 mm × 5 mm rectangle to form a laser heating section. The laser heating unit and the water cooling unit (water temperature: 25 to 30 ° C., size: 30 mm × 2 mm) were arranged apart by a predetermined distance d. Here, the long sides of the laser heating part and the water cooling part were arranged along the moving direction of the steel sheet pieces. And the laser heating part and the water cooling part were passed in this order, moving the said steel plate piece at the speed | rate of 25 mm / sec. Laser irradiation and water cooling were performed over a range of width 19 mm × length 120 mm on the steel plate piece. The distance d between the laser heating part and the water cooling part was 10 mm in Example 1 and 20 mm in Example 2.

(Comparative example)
A sample piece according to Comparative Example 1 was obtained by performing laser irradiation with a laser heating unit on the same steel plate piece as used in the example under the same conditions as in the example. However, unlike the case of the example, water cooling by the water cooling unit was not performed, and only air cooling at room temperature was performed.

[Test method]
(Evaluation of hardness)
The hardness of the sample piece in the plate width direction (short side direction) was measured with respect to the site where each sample piece according to the example and the comparative example was irradiated with laser. The measurement was performed using a micro Vickers hardness tester.

(Evaluation of tensile strength)
Using each sample piece according to the example and the comparative example, the site where the laser irradiation was performed was arranged in the center to prepare a test piece as shown in FIG. And the tensile test was done based on JISZ2241 and the tensile strength was measured.

(Evaluation of elongation)
Using each sample piece concerning an Example and a comparative example, the test piece similar to the said tensile strength test was created, the tensile test was done based on JISZ2241, and breaking elongation was measured.

(Evaluation of metal structure)
About each sample piece concerning an Example and a comparative example, the surface was observed using the scanning electron microscope (SEM).

[Results and discussion]
Table 1 shows the measurement results of hardness, tensile strength, and elongation obtained for each sample piece according to Examples and Comparative Examples. Moreover, the obtained SEM image is shown in FIG.

  Since the steel plate piece before laser irradiation had a hardness of Hv152 and a tensile strength of 440 MPa (nominal value), the hardness and the tensile strength were measured by laser irradiation in any of the comparative examples and the examples. It has improved by going through. This is because the steel was quenched by laser irradiation.

  However, in Comparative Example 1, hardness and tensile strength are slightly improved, whereas in Examples 1 and 2, these values are greatly improved. This is because the SEM images of Examples 1 and 2 (FIG. 5A, 5), which were water-cooled, compared to the SEM image of Comparative Example 1 (FIG. 5C) which was not water-cooled after laser irradiation. In b)), it is considered that this corresponds to the observation of a dense and fine structure. That is, it is interpreted that by rapidly cooling the steel heated by the laser irradiation, a fine martensite structure is formed, and the hardness and strength of the steel are remarkably improved.

  Comparing Example 1 and Example 2, Example 2 with a longer distance d between the laser heating part and the water cooling part is superior in hardness and tensile strength, but is inferior in elongation. Further, comparing the SEM images, a finer structure is formed in the case of Example 1 in FIG. 5A than in the case of Example 2 in FIG. This means that when the distance between the laser heating part and the water cooling part is large, the part irradiated with the laser is kept in a high temperature state for a long time, and quenching proceeds, so that the hardness and the tensile strength are increased. While the improvement progresses, the metal structure becomes coarse, which indicates that the elongation decreases.

  When manufacturing various steel members such as vehicle parts, it is required to improve hardness and tensile strength and to maintain elongation at a high level. That is, it is required that hardness, tensile strength, and elongation are balanced. In this respect, the sample piece of Example 1 is preferable to the sample piece of Example 2, and as a guide, the distance between the laser heating part and the water cooling part is the length of the laser heating part (in this case, 19 mm) or less. Note that in a vehicle seat, SPC980 material is used in a portion where a load is applied intensively, such as the front and rear end edges of a side frame, or a portion where sliding occurs such as a portion where a ball bearing of a slide rail abuts. It is desired that a hardness and a tensile strength corresponding to the above can be obtained, and it is desirable that the elongation is comparable to that of the SPC980 material. SPC980 material generally has a hardness of Hv200 and an elongation of 12-13%. The sample piece according to Example 1 has higher tensile strength and hardness than the SPC980 material, and has achieved an elongation of a close value, and a good balance between hardness and tensile strength and elongation. It can be said that is obtained.

  As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to the said embodiment and Example, A various change is possible in the range which does not deviate from the summary of this invention.

DESCRIPTION OF SYMBOLS 1 Laser beam 2 Water cooling part 3 Laser irradiation part 3A Laser heating part 3B Preheating part 10 Carbon steel material 20 Side frame 21 Front and rear edge 30 Slide rail 31 Lower rail 32 Upper rail 33a Upper sliding space 33b Lower sliding space M Process progress direction

Claims (4)

  A laser heating unit that irradiates and heats a carbon steel material with a laser beam and a water cooling unit that cools the carbon steel material by bringing water into contact therewith are arranged side by side, and the carbon steel material is disposed with respect to the laser heating unit and the water cooling unit. The method for producing a steel member is characterized in that a part of the carbon steel material is irradiated with laser light by the laser heating unit while being moved relatively, and then water is brought into contact with the water cooling unit.   2. The method for manufacturing a steel member according to claim 1, wherein the width of the water-cooled portion along the direction intersecting the direction of relative movement of the carbon steel material is wider than the width of the laser heating portion.   The distance between the laser heating unit and the water cooling unit along the direction of relative movement of the carbon steel material is equal to or less than the length of the laser heating unit along the direction of relative movement of the carbon steel material. The manufacturing method of the steel member of Claim 1 or 2 characterized by these.   The carbon steel material is irradiated with a laser beam having an energy density lower than that of the laser heating unit in the preheating unit before being irradiated with the laser beam by the laser heating unit. 4. The method for producing a steel member according to any one of 3 above.