JP3542229B2 - Tempering method of steel - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a method for quenching and tempering steel.
[0002]
[Prior art]
Conventionally, so-called quenching treatment has been performed to increase the surface hardness of steel materials and improve wear resistance and fatigue strength.
In such quenching, quenching heating is performed to heat the steel material to a temperature equal to or higher than the austenite transformation point, and then the steel material is rapidly cooled to transform the austenite phase into a martensite phase. This martensite is very hard and is very effective in increasing the hardness of steel.
[0003]
On the other hand, as a method of rapidly quenching the surface layer of a steel material, for example, a method of irradiating a high-density energy beam to rapidly heat the surface layer of the steel material and then rapidly cool the steel material has been proposed (Japanese Patent Application No. Hei 7-1995). No. 345160). In this proposal, it is shown that a very excellent quenching effect can be obtained if the heating is performed using energy high enough to melt the surface layer of the steel material.
[0004]
In other words, by heating steel at a temperature higher than the temperature at which its surface layer melts, and then quenching, not only the molten portion of the surface layer, but also the lower layer becomes martensite in a relatively deep range, resulting in high hardness quench hardening. The layer can be formed relatively deep. Therefore, an extremely excellent hardness improving effect can be obtained.
[0005]
[Problem to be solved]
However, the above method has the following problems.
That is, according to the method of quenching by heating and quenching the steel material above the melting temperature of the steel material (hereinafter referred to as melt quenching as appropriate), while an excellent quenching effect is obtained, while the residual tensile stress during resolidification of the surface molten layer is reduced. appear.
[0006]
This residual tensile stress is not only a cause of quenching distortion, but also easily causes quenching cracks and breakage, and is harmful.
As a countermeasure, there is a method in which the quenched portion is again heated to a temperature lower than the austenite transformation point and tempered. According to this, the residual stress is sufficiently removed.
[0007]
However, in the tempered portion, while the residual stress is removed, the hardness of the tempered portion is reduced and the quenching effect is reduced. A tempering method at a low temperature is also conceivable, but the residual stress is hardly removed, and is not a fundamental solution. Therefore, it is very problematic to perform tempering heating on steel materials that require a sufficient improvement in surface hardness.
[0008]
On the other hand, depending on the steel material, there is a case where the effect of improving hardness as much as the above-mentioned melt quenching is not necessary. In this case, it is conceivable to change the method to a method in which the heating is performed at a temperature equal to or higher than the austenite transformation point of the steel material and equal to or lower than the melting temperature, followed by rapid cooling (hereinafter, appropriately referred to as non-melting quenching).
[0009]
However, in the case of this non-melting quenching, although the desired hardness is obtained and the tensile residual stress in the surface layer is eliminated, on the contrary, the compressive stress is applied to the surface layer by volume expansion due to transformation from austenite to martensite. Will occur. On the other hand, performing the tempering heating in the same manner as described above is effective for removing the compressive residual stress, but cannot reduce the effect of improving the hardness.
[0010]
The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a method for tempering steel, which can maintain the effect of increasing hardness by quenching and control residual stress.
[0011]
[Means for solving the problem]
According to the invention of claim 1, the steel material is quenched and heated to a temperature equal to or higher than the austenite transformation point and then rapidly cooled.
Next, there is provided a method of tempering steel by tempering at a temperature lower than the austenite transformation point,
The above tempering heatingIn the desired part of refining,The as-quenched part and the tempered partAlternatelyA method for tempering steel, characterized in that the quenching is performed partially on a quenched portion that is quenched and heated so as to be formed adjacently.
[0012]
Most notably, in the present invention, the tempering heating is performed partially on the quenched and heated quenched portion, and the as-quenched portion and the tempered portion are formed adjacent to each other. Is to do so.
In the present invention, the as-quenched portion also includes a portion which is substantially quenched due to incomplete removal of residual stress such as when low-temperature tempering is performed.
[0013]
Examples of the steel material targeted in the present invention include carbon steel such as S50C, S23C and S10C, alloy steel such as SNCM, SCR and SCM, and tool steel such as SK, SKD, SKH and SKS.
[0014]
The quenching heating is performed at a temperature equal to or higher than the austenite transformation point as described above. That is, the quenching heating is performed in the iron-carbon system equilibrium diagram shown in FIG.₃Perform at a temperature above the line. As a result, the steel material becomes austenite, and by rapidly cooling this, the austenite is transformed into martensite and becomes a quenched hardened layer. On the other hand, the temperature below the austenite transformation point (A₃When the temperature is below the temperature, austenite cannot be obtained by heating, and martensitic transformation by rapid cooling cannot be obtained.
[0015]
The tempering heating is performed at a temperature lower than the austenite transformation point as described above. That is, this will be described with reference to the iron-carbon system equilibrium diagram shown in FIG.₃Perform at a temperature below the line. On the other hand, the tempering₃When the temperature is higher than the temperature, there is a problem that the quench hardening effect disappears.
[0016]
Next, the operation of the present invention will be described.
In the method for tempering steel according to the present invention, the tempering heating is partially performed on the quenched portion, and the as-quenched portion and the tempered portion are formed adjacent to each other.
[0017]
At this time, the residual stress remains in the quenched portion, but the residual stress is sufficiently removed in the tempered portion. The residual stress remaining portion and the residual stress removing portion exist adjacent to each other. Therefore, as a whole, the residual stress is greatly reduced, and the occurrence of the conventional quenching distortion can be prevented.
[0018]
The hardness of the tempered part heated by the tempering is lower than that of the as-quenched state. However, in the present invention, the quenched portion is arranged adjacent to the tempered portion. For this reason, it is possible to maintain an average high hardness as compared with the case where the whole is tempered and heated.
Therefore, it is possible to control the residual stress while maintaining the effect of increasing the hardness by quenching.
[0019]
Next, as in the second aspect of the present invention, the quenching heating is preferably performed at a temperature at which the surface layer of the steel material is melted. More specifically, in the quenching heating, for example, in the iron-carbon system equilibrium diagram of FIG.₁In the case of, the surface layer of the steel material is P₂It is preferable to heat to the above temperature.
[0020]
As a result, not only the molten portion of the surface layer but also the lower layer portion is martensitized in a relatively deep range by the rapid quenching, so that a hardened layer with high hardness can be formed relatively deeply. Therefore, an extremely excellent hardness improving effect can be obtained.
However, in this case, the residual stress remaining in the as-quenched portion becomes a tensile residual stress. This is due to the coagulation shrinkage phenomenon.
[0021]
Further, as in the invention of claim 3, the quenching heating can be performed at a temperature at which the surface layer of the steel material is not melted. More specifically, in the quenching heating, for example, in the iron-carbon system equilibrium diagram of FIG.₁In the case of, the surface layer of the steel material is P₁P₂It can be heated to a temperature below.
[0022]
In this case, although the formation of the quenched and hardened layer is shallower than in the case of heating accompanied by melting of the steel material surface layer, a sufficient hardness improving effect can be obtained as compared with the case of not quenching.
However, in this case, the residual stress remaining in the as-quenched portion becomes a compressive residual stress. This is because of the volume expansion accompanying the transformation from austenite to martensite.
[0023]
Further, as in the fourth aspect of the present invention, the quenching heating and the tempering heating can be performed only on a desired portion of the steel material to be tempered. Here, the desired part for refining refers to a part of the steel material which is to be hardened by quenching. Thereby, a quenched and hardened portion can be formed only in a necessary portion according to the characteristics of the product, and a portion having, for example, a relatively soft and tough property can be left in other portions.
[0024]
Further, as in the invention of claim 5, the quenching heating to a temperature higher than the austenite transformation point and the tempering heating to a temperature lower than the austenite transformation point include:Using high density energyIt is preferred to do so. Thereby, the quenching heating and the tempering heating can be efficiently performed with good response. Therefore, high productivity and stable quality can be obtained. thisUsing high density energyThe method is particularly effective when it is desired to partially quench only the desired portion for refining.
[0025]
the aboveHigh density energyFor example, electron beam, laser beamHigh density energy beam, And not a beam but high-density energy such as high-frequency heating.The electron beam is generated by applying a high voltage to the electron beam gun. The laser light is generated by applying a high voltage to a laser oscillator.
Further, as in the invention of claim 6, the high-density energy is a high-density energy beam, and the quenching heating and the tempering heating are performed by irradiating the steel material with the high-density energy beam. preferable.
[0026]
next,Claim 7As described above, the high-density energy beam uses a quenching heating beam for heating a steel material to a temperature equal to or higher than the austenite transformation point and a tempering heating beam for heating a steel material to a temperature lower than the austenite transformation point. First, the steel material is quenched and heated by a quench heating beam, and then the tempering heating beam is intermittently irradiated to the quenched part rapidly cooled to a temperature below the martensitic transformation point. .
[0027]
In this case, since the steel material is successively irradiated with the quenching heating beam and the tempering heating beam, the two heat treatments (the quenching heating to a temperature higher than the austenite transformation point and the heat treatment below the austenite transformation point) are performed. Tempering heating) can be continuously performed. Therefore, the above-mentioned heating, rapid cooling, and reheating can be performed with higher response. The term “intermittently irradiating the tempering heating beam” means that the operation of irradiating only the portion corresponding to the tempered portion without repeating the portion corresponding to the as-quenched portion is repeated. .
[0028]
The rapid cooling can be achieved by providing a slight time interval between the irradiation of the quench heating beam and the irradiation of the tempering heating beam. That is, during this time interval, the heat given to the steel material by the quenching heating beam is rapidly transmitted into and out of the steel material, and the steel material is rapidly cooled.
The time interval is the time required for the quenched and heated portion of the steel to reach a temperature below the martensitic transformation point.
[0029]
next,Claim 8As described above, the high-density energy beam can irradiate a beam emitted from one beam source at a plurality of locations. In this case, one high-density energy beam is divided into a plurality by a deflection control device or the like. As a result, a single high-density energy beam can be simultaneously distributed and irradiated to a plurality of desired portions of the steel material, and the irradiation equipment can be downsized.
[0030]
next,Claim 9As in the invention of the above, the rapid cooling is 10^ThreeIt is preferable to carry out at a rate of at least ° C / min. 10 above^ThreeIf the temperature is lower than ℃ / minute, martensitic transformation may not occur sufficiently. The upper limit is preferably as fast as possible, but is limited by the thermal conductivity of the steel.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1
A method of tempering a steel material according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIGS. 2 to 4, the tempering method of the steel material of the present embodiment is such that the desired tempering portion 20 of the steel material 2 (FIG. 2) as the material to be treated is at or above the austenite transformation point (A in FIG. 4).₃Quenching and heating to a temperature accompanied by melting of the surface layer and then quenched, and then a temperature below the austenite transformation point (A in FIG. 4).₃(Less than the line).
[0032]
For the sake of simplicity, the explanation will be made with reference to an iron-carbon binary system equilibrium phase diagram. However, these transformation temperatures not only depend on the steel composition, but also with rapid heating, the transformation temperature rises to the high temperature side and rapid cooling occurs. It is known that the transformation temperature shifts to a lower temperature side, and the numerical value of the transformation temperature of the steel is not specifically limited as shown in FIG.
[0033]
As shown in FIG. 1, the quenching heating is performed partially on the quenched and heated quenched portion so that the as-quenched portion B and the tempered portion A are formed adjacent to each other. Do. As described above, the quenching in this example is referred to as melt quenching for convenience because the quenching heating is performed at a temperature at which the surface of the steel material is melted.
[0034]
That is, as shown in FIG. 3A, the tempered portion A in the desired tempering portion 20 has an austenite transformation point T.₄The melting temperature T₅Heat to the above temperature 31 and then martensite transformation point T₃Quenched to a temperature of less than 34 and then again at the austenite transformation point T₄Heat treatment is performed by a heat pattern of heating to a temperature of less than 33.
[0035]
On the other hand, as shown in FIG. 3 (b), the part B of the desired temper 20 that has been melt-quenched has an austenite transformation point T.₄And the melting temperature T₅Is heated to the above temperature 31 and then the martensitic transformation point T₃The heat treatment is performed according to a heat pattern of being rapidly cooled to a temperature of less than 34.
[0036]
Further, as shown in FIG. 2, the quenching heating and the tempering heating in the present embodiment are performed by irradiating high-density energy beams 11 and 12 to a desired portion 20 of the steel material 2 to be reconditioned. That is, as shown in FIGS. 2 (a) and 2 (b), a high-density energy beam 10 is emitted from a high-density energy beam source 1 and is used as a quench heating beam 11 having a high output in the case of quenching heating. In the case of tempering heating, the beam is switched to a tempering heating beam 12 having a low output.
[0037]
Irradiation of the high-density energy beams 11 and 12 is performed by first irradiating the quenching and heating beam 11 to the entire tempered portion 20 of the steel material 2 in advance, and then only the tempered portion A of the tempered desired portion 20. The process is performed in such a manner that the tempering heating beam 12 is irradiated.
Specifically, as shown in FIG. 2, the quenching and heating beam 11 is first applied to the desired tempering portion 20 while moving the steel material 2 in the direction of the arrow in FIG.
[0038]
The portion 21 irradiated with the quenching heating beam 11 is rapidly self-cooled immediately after the completion of the irradiation, and is sufficiently rapidly cooled before the tempering heating is started.
Next, after the completion of the quenching heating, the high-density energy beam is switched to the tempering heating beam 12, and while the beam is turned on and off, the moving desired refining portion 20 is irradiated. The portion 22 irradiated with the tempering heating beam 12 becomes a tempered portion A. Therefore, the portion that has not been irradiated with the tempering heating beam 12 is the portion B that has been melt-quenched.
[0039]
As described above, in this example, as shown in FIG. 1, the portions B and the tempered portions A which are still quenched are formed alternately adjacent to each other. Therefore, as shown in FIG. 5, the portion B which has been melt-quenched has a tensile residual stress state 81 (FIG. 5 (a)), while the tempered portion A has no residual stress 82 (FIG. 5 (b)). From a viewpoint, these are alternately present to form a sine curve 83 (FIG. 5C).
[0040]
That is, the desired portion 20 of the tempering of the steel material 2 is, as a whole, in a state where the residual stress is remarkably relaxed as compared with the as-quenched state.
Therefore, it is possible to sufficiently prevent defects such as generation of distortion and cracks caused by residual stress after the melt quenching treatment.
[0041]
Further, as shown in FIG. 1, the tempered portion A has a relatively low hardness. However, in this example, the portions B that have been melt-quenched are arranged alternately adjacent to the tempered portions A as described above. The part B which has been melt-quenched has extremely high hardness. Therefore, the hardness of the entire desired portion 20 for refining is maintained at a sufficiently high hardness.
Therefore, in this example, it is possible to control the residual stress while maintaining the effect of increasing the hardness by quenching.
[0042]
Embodiment 2
In this example, as shown in FIG. 6, a series of the above-described quenching heating and tempering heating in the first embodiment was performed while sequentially shifting the positions in a plurality of rows. That is, in the tempering desired portion 20 of the steel material 2, tempered portions A and portions B that have been melt-quenched vertically and horizontally are alternately arranged in a checkered pattern.
[0043]
In this case, when processing a relatively wide refining desired portion 20, the portions A and B having different properties as described above are arranged with good balance in the vertical and horizontal directions, and the effect of the first embodiment is further improved.
[0044]
Embodiment 3
In the present embodiment, in the first embodiment, the quenching heating was performed at a temperature at which the surface layer of the steel material was not melted. Then, it was quenched and non-melting quenched as it were. Specifically, as shown in FIGS. 3 (a) and 3 (b), both the tempered portion A and the as-quenched portion B have the initial quenching heating temperature of the austenite transformation point T.₄The melting temperature T₅The temperature was set to less than 32. Others are the same as the first embodiment.
[0045]
In this example, as shown in FIG. 7A, a tempered portion A and a non-melted and quenched portion B were alternately formed adjacent to each other. As a result, as shown in FIG. 8, the unmelted and quenched portion B has a compressive residual stress state 84 (FIG. 8A), while the tempered portion A has no residual stress 85 (FIG. 8B). When viewed continuously, these exist alternately to form a sine curve 86 (FIG. 8C).
[0046]
That is, the desired portion 20 of the tempering of the steel material 2 is, as a whole, in a state where the residual stress is remarkably relaxed as compared with the as-quenched state.
Therefore, it is possible to sufficiently prevent problems such as generation of distortion and cracks caused by residual stress caused by the non-melting quenching treatment.
[0047]
Further, as shown in FIG. 7 (c), the tempered portion A has a relatively low hardness. However, in this example, the portions B which are not melt-quenched are arranged so as to be alternately adjacent to the tempered portions A as described above. The unmelted and quenched portion B has a lower hardness than that of the melt quenching, but has a sufficiently higher hardness than the tempered portion A. Therefore, the hardness of the entire desired portion 20 for refining is maintained at a high hardness.
Therefore, in this example, it is possible to control the residual stress while maintaining the hardness improving effect by non-melting quenching.
[0048]
In this example, as shown in FIG. 9, the above-described series of processing is repeated while shifting the position in the width direction, and the tempered portion A and the non-melted and quenched portion B are alternately arranged in a checkered pattern vertically and horizontally. If you do, it will be more effective.
[0049]
Embodiment 4
As shown in FIGS. 10 to 12, in this example, in the method of tempering a steel material shown in the first embodiment, while rotating the steel material 2, a desired ring-shaped refining portion 20 (FIG. 11, FIG. FIG. 12) is first irradiated with a quenching heating beam 11 (FIG. 11) and then with a tempering heating beam 12 (FIG. 12), showing a heat treatment apparatus and method.
[0050]
In this example, the steel material 2 as the material to be processed is a lock-up clutch piston of a torque converter component. This piston has a dish shape (see FIGS. 10 and 13). Then, a ring-shaped quenching refining is applied to a part thereof (FIGS. 11 and 12).
As shown in FIG. 10, the heat treatment apparatus includes a processing chamber 19 in which a steel material 2 is placed, a beam source 1 for irradiating the processing chamber 19 with the high-density energy beam 10, and a high-density beam from the beam generation source 1. It has deflection coils 111 and 112 for switching the energy beam 10 between a quenching heating beam and a tempering heating beam.
[0051]
Further, it has a vacuum evacuation device 16 for reducing the pressure in the processing chamber 19 and a high-speed deflection control device 110 for high-density energy beams in the deflection coils 111 and 112. By changing the frequency and waveform of the current flowing through the deflection coils 111 and 112, the output of the high-density energy beam 10 can be changed arbitrarily and switched between the quenching heating beam and the tempering heating beam. A rotation motor 150 for rotating the mounting table 15 of the steel material 2 is provided below the processing chamber 19.
These devices are controlled by the general controller 17.
[0052]
When the steel material is quenched by the heat treatment apparatus, first, the rotary motor 150 is driven to rotate the steel material 2 at a speed of about 8 m / min in the direction of the arrow in FIGS. . The processing chamber 19 is evacuated by the vacuum exhaust device 16.
[0053]
Then, as shown in FIG. 11, the steel material 2 is rotated once while irradiating a high-density energy beam having an output of 3.5 KW as a quenching heating beam 11 to the desired portion 20 for heat treatment of the steel material 2. The portion irradiated with the quenching heating beam 11 is rapidly cooled by self-cooling immediately after the completion of the irradiation. Next, the output of the high-density energy beam is reduced and the tempering heating beam 12 of 1.5 KW is intermittently irradiated. That is, the steel material 2 is made to idle without irradiating the as-quenched portion B, and is irradiated only to the tempered portion A.
[0054]
As described above, the ring-shaped quenching process and the tempering process are completed when the steel 2 rotates twice. That is, in this example, the part B and the tempered part A that have been melt-quenched can be reliably formed in the steel material 2 adjacent to each other in a short time.
Therefore, in this example, the processing can be performed reliably and quickly, and the same effect as in the first embodiment can be obtained.
[0055]
Embodiment 5
This example is a specific example using the method and apparatus for quenching a steel material shown in the first and fourth embodiments.
That is, as shown in FIG. 13, the steel material to be processed in this embodiment is the lock-up clutch piston 41 used for the torque converter.
[0056]
The lock-up clutch piston 41 is partially caulked and fixed to a damper device for absorbing a change in transmission torque in a torque converter. Note that reference numeral 43 in the figure is a mounting hole.
As shown in FIG. 13, the damper device includes a driven plate 51 and springs 52 and 53 which are rotated integrally with the turbine liner.
[0057]
Here, as shown in FIG. 13, the springs 52 are for the first stage disposed at eight locations in the circumferential direction of the lock-up clutch piston 41, and the spring 53 is for the circumferential direction of the lock-up clutch piston 41. , For the second stage disposed at four positions, and this spring 53 is disposed every other in the spring 52. The spring 53 has a smaller diameter and a shorter diameter than the spring 52, and starts to bend after the torsion angle of the spring 52 reaches a set value and the transmission torque reaches the bending point torque.
[0058]
Therefore, the rotation transmitted from the front cover via the friction material is transmitted to the turbine hub via the damper device. At this time, the springs 52 and 53 contract to absorb the fluctuation of the transmission torque during the rotation transmission. I do. Further, it plays a role of preventing vibration, noise, and the like caused by transmission of “sudden fluctuation of engine output torque” to a transmission (not shown).
[0059]
Incidentally, when the lock-up clutch piston 41 is driven forward (when the lock-up clutch device is placed in the engaged state and the lock-up clutch piston 41 rotates counterclockwise in FIG. 13) and when it is driven in reverse (when the engine When the lock-up clutch piston 41 rotates clockwise in FIG. 13, for example), the spring 52 is compressed, and the spring 52 tends to repeatedly slide with the flat plate portion 411 of the lock-up clutch piston 41. It becomes.
[0060]
For this reason, there is a problem in that the flat portion 411 of the lock-up clutch piston 41 generates friction due to sliding with the spring 52.
The lock-up clutch piston 41 has a part of a donut-shaped spring receiver 40 (hatched part in FIG. 13) that comes into contact with the spring 52.
[0061]
The spring receiver 40 of the lock-up clutch piston is required to have wear resistance and the like. Therefore, it is necessary to partially perform a surface hardening treatment on the spring receiving portion (thickness: 3 mm).
The material of the component is S23C.
[0062]
In performing the quenching and tempering processes, the quenching heating and the tempering heating used the electron beam as the high-density energy beam shown in the first and fourth embodiments.
The above-mentioned electron beam generator has a maximum output of 5 KW, and can switch and emit between a 3.5 KW electron beam as a quenching heating beam and a 1.5 KW electron beam as a tempering heating beam. it can.
[0063]
Then, the above-mentioned component is rotated at a feed speed of about 8 m / min at 10 rpm, and a beam having a radius of 127 mm is irradiated with a quench heating beam 11 for one rotation as shown in Embodiment 4, and then tempered. The heating beam 12 was switched on and off, and irradiation was performed intermittently.
[0064]
As shown in FIG. 14, the quenching heating beam 11 and the tempering heating beam 12 both have deflection trajectories of 5 mm in the X direction and 10 mm in the Y direction. The trajectory of the electron beam moves in the direction of arrow H due to the rotation of the component.
The quenched and heated portion is sufficiently quenched immediately after heating by self-cooling of the steel material 2 and quenched.
[0065]
As a result of the above treatment, the as-quenched portion B and the tempered portion A were alternately formed adjacent to the desired portion 20 for tempering of the steel material 2.
As a result, in the above-mentioned component, the above-mentioned spring receiving portion was formed into a ring-shaped portion having an average sufficiently high hardness. On the other hand, the residual stress was sufficiently relaxed on average compared to the conventional case.
[0066]
Embodiment 6
In this example, as shown in FIGS. 15 and 16, the high-density energy beams emitted from one beam source are used by the deflection coils 111 and 112 (FIG. 10) using the heat treatment apparatus shown in the fourth embodiment. The beam was divided into two beams by using the quenching and heating beams 11 and the tempering and heating beams 12, respectively.
[0067]
That is, as shown in FIGS. 15 and 16, the quenching and heating beam 11 and the tempering and heating beam 12 are sequentially irradiated at regular intervals while rotating the steel material 2 in the direction of the arrow. Further, the tempering heating beam 12 repeats on and off to irradiate only the tempered portion A.
Others are the same as the first, fourth, and fifth embodiments.
[0068]
In this case, the above series of heat treatments can be performed by one rotation of the steel material 2. Therefore, the processing can be completed in a shorter time than in the above embodiment, which is very efficient.
[0069]
Embodiment 7
In this example, FIG. 17 shows an example of the irradiation locus of the electron beam when two electron beams are irradiated in the sixth embodiment.
In this example, the electron beam has two circular deflection trajectories C₁, C₂Irradiated according to In this case, each circular deflection locus C₁, C₂Thus, the heat-treated regions 25 and 26 are irradiated with an electron beam, during which the member to be heat-treated is rotated around its central axis. Accordingly, the trajectory of the electron beam in the heat treatment region 25.26 moves in the direction of arrow H.
[0070]
Note that each circular deflection locus C₁, C₂Generates a sinusoidal deflection waveform in the x-axis direction and the y-axis direction, and is formed by a combination of the deflections. In addition, each circular deflection locus C₁, C₂In order to alternately irradiate the electron beam in the adjacent heat treatment regions 25 and 26, the deflection waveform w shown in FIG.₁Is generated, and the deflection waveform w₁And the deflection waveform in the y-axis direction are superimposed.
[0071]
Therefore, the voltage V_ETakes a positive value t₁During this time, the region 25 to be heat-treated is irradiated with an electron beam and the voltage V_ETime t takes a negative value₂During this time, the electron beam is irradiated to the region to be heat-treated 26.
The deflection waveform w₁Time t₁, T₂By adjusting the length, the irradiation energy to each of the heat treatment regions 25 and 26 can be adjusted.
[0072]
Embodiment 8
In this example, as shown in FIG. 19, there is shown another example in which the regions to be heat-treated are irradiated with an electron beam.
In this case, two surface deflection trajectories C₃, C₄Irradiates an electron beam. That is, each surface deflection locus C₃, C₄Thus, the regions to be heat-treated are irradiated with electron beams respectively, during which the member to be processed is rotated around its central axis. Therefore, also in this case, the locus of the electron beam in the regions to be heat-treated 27 and 28 moves in the direction of arrow H.
[0073]
Note that each surface deflection locus C₃, C₄Is formed by generating a triangular wave deflection voltage in the x-axis direction and the y-axis direction. In addition, each surface deflection locus C₃, C₄To irradiate the electron beam in the regions to be heat-treated 27 and 28, the deflection waveform w as shown in FIG.₁And the triangular waves in the x-axis direction and the y-axis direction are superimposed.
Of course, it is also possible to combine circular deflection and surface deflection, or to deflect the electron beam so as to follow a locus such as a line or an ellipse. Others are the same as the sixth embodiment.
[0074]
By the way, in the above-described embodiment, an example in which the lock-up clutch piston of the torque converter is processed has been described. In addition, for example, a plate sliding portion in a multi-plate frictional engagement device, a connecting portion between members or a snap ring or the like, The present invention can be applied to any steel member, such as a pump plate and a seal ring, which needs to be hardened while controlling the residual stress of the surface layer in whole or in part.
[0075]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the tempering method of steel materials which can maintain the hardness improvement effect by quenching and can control residual stress can be provided.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing (a) a heat treatment pattern, (b) a residual stress pattern, and (c) a hardness pattern in the first embodiment.
FIG. 2A is a side view and FIG. 2B is a plan view showing an irradiation state of a high-density energy beam in the first embodiment.
FIG. 3 is an explanatory view showing heat patterns of (a) a tempered portion and (b) a portion as it is melt-quenched in the first embodiment.
FIG. 4 is an explanatory diagram showing an iron-carbon system equilibrium diagram.
FIG. 5 is an explanatory view showing the residual stress state of (a) a part as it is melt-quenched, (b) a tempered part, and (c) the whole in the first embodiment.
FIG. 6 is an explanatory view showing a heat treatment pattern in the second embodiment.
FIG. 7 is an explanatory view showing (a) a heat treatment pattern, (b) a residual stress pattern, and (c) a hardness pattern in the third embodiment.
FIG. 8 is an explanatory view showing a residual stress state of (a) a part that has not been melt-quenched, (b) a tempered part, and (c) the whole, in a third embodiment.
FIG. 9 is an explanatory view showing another heat treatment pattern in the third embodiment.
FIG. 10 is an explanatory diagram of a heat treatment apparatus according to a fourth embodiment.
FIG. 11 is an explanatory diagram showing an irradiation state of a quenching heating beam in a fourth embodiment.
FIG. 12 is an explanatory view showing an irradiation state of a tempering heating beam in a fourth embodiment.
FIG. 13 is an explanatory view of a lock-up clutch piston according to a fifth embodiment.
FIG. 14 is an explanatory diagram showing an example of a locus of an electron beam irradiation unit in the fifth embodiment.
15A is a side view and FIG. 15B is a plan view showing an irradiation state of a high-density energy beam in the sixth embodiment.
FIG. 16 is an explanatory diagram showing an irradiation state of a high-density energy beam in the sixth embodiment.
FIG. 17 is an explanatory diagram showing an example of a trajectory of an electron beam irradiation unit in the seventh embodiment.
FIG. 18 is an explanatory diagram showing an example of a deflection waveform of electron beam irradiation in the seventh embodiment.
FIG. 19 is an explanatory diagram showing another example of the trajectory of the electron beam irradiation unit in the seventh embodiment.
FIG. 20 is an explanatory diagram showing an example of a deflection waveform of electron beam irradiation in the seventh embodiment.
[Explanation of symbols]
1. . . Source of high-density energy beam,
10. . . High density energy beam,
11. . . Quenching beam,
12. . . Tempering heating beam,
2. . . Steel,
20. . . Tempering desired part,
A. . . Tempering part,
B. . . As-quenched part (melt-quenched or unmelted-quenched part),

Claims (9)

After quenching and heating the steel beyond the austenite transformation point, it is rapidly cooled,
Next, there is provided a method of tempering steel by tempering at a temperature lower than the austenite transformation point,
The above-mentioned tempering heating is partially performed on the quenched and heated quenched portion such that the as-quenched portion and the tempered portion are alternately formed adjacent to each other in the desired tempering portion. Tempering method for steel materials. 2. The method for tempering steel according to claim 1, wherein the quenching heating is performed at a temperature accompanied by melting of the surface layer of the steel. 2. The method for tempering steel according to claim 1, wherein the quenching heating is performed at a temperature at which the surface layer of the steel does not melt. In any one of claims 1 to 3, the sintered and enter the heating and tempering heated, tempered method of the steel, which comprises carrying out only for the refining desired portion of the steel. The quenching heating to a temperature higher than the austenite transformation point and the tempering heating to a temperature lower than the austenite transformation point are performed using high-density energy according to any one of claims 1 to 4. Tempering method for steel materials. 6. The tempering method according to claim 5, wherein the high-density energy is a high-density energy beam, and the quenching heating and the tempering heating are performed by irradiating the steel with the high-density energy beam. . In claim 6 , the high-density energy beam uses a quenching heating beam that heats a steel material to a temperature equal to or higher than the austenite transformation point and a tempering heating beam that heats a steel material to a temperature lower than the austenite transformation point. ,
First, the steel material is quenched and heated by a quench heating beam, and then the tempering heating beam is intermittently irradiated to the quenched part rapidly cooled to a temperature below the martensitic transformation point. Tempering method of steel material. 8. The tempering method according to claim 6, wherein the high-density energy beam is irradiated by distributing a beam emitted from one beam source to a plurality of locations. According to any one of claims 1-8, said rapid cooling is tempered method steel material characterized by performing at 10 ³ ° C. / min or faster.

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