JP2002371315A - Method for manufacturing metal member and metal member manufactured therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a metal member, which does not retain a liquid refrigerant between a hardening tool and a metallic molding, and uniformly hardens the molding through consequently uniform cooling, when hardening the metal molding with the hardening tool. SOLUTION: The method for manufacturing the metal member comprising a preparation step of preparing the metal material for molding, a molding step of molding the prepared metal material into a predetermined shape of the metallic molding W, a hardening step of heating the metallic molding W with a hardening tool 21 of a non-contact type, and cooling it by supplying a liquid refrigerant 32 to harden it, is characterized by vibrating the metallic molding W in the hardening step, so as to prevent the liquid refrigerant 32 from being retained between the metallic molding W and the hardening tool 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a metal member and a metal member manufactured by the method.

[0002]

2. Description of the Related Art Since a body frame of an automobile constitutes a skeleton of the automobile, a high strength is required so that the frame is not easily deformed upon collision with an object. On the other hand, the vehicle body frame member, which is a metal member constituting the vehicle body frame, is made of, for example, a steel plate that is formed into a hat shape having a substantially trapezoidal cross section by press forming. Excellent press moldability is also required.

As a method of manufacturing a metal member satisfying both of these requirements, there is known a method of press-forming an easily deformable steel plate into a predetermined shape and then quenching the press-formed product to increase the strength. In this method, the metal structure is austenitized by heating a press-formed product, and the metal structure is transformed into hard martensite by quenching it to strengthen the metal structure.

For example, Japanese Patent Application Laid-Open No. Hei 6-116630 discloses a method of locally hardening only a portion of a vehicle body that requires strength using an induction hardening coil mounted on the end of an arm of a robot device. As a result, it is possible to abolish the reinforcement and reduce the number of attachment points, so that it is possible to reduce the weight of the automobile body and the production cost, and to reduce the thickness of the steel sheet constituting the automobile body. It is described that the press workability of the steel sheet becomes extremely good because it becomes possible, and that the equipment investment can be suppressed low because the coil for induction hardening is used.

Japanese Patent Application Laid-Open No. 10-17933 discloses that a press-formed product made of steel containing 0.07 to 0.2% by mass of carbon (C) exhibits a hardness change corresponding to a desired strength distribution. It is disclosed that the press-formed product is quenched by a heating means based on a high-frequency current and cooled by a cooling means in contact with a coolant such as water so as to have a hardness distribution exhibited. The press-formed product can secure the strength by the quenching region, and when another object collides, it can secure the deformation preventing property in the high hardness portion of the quenching region,
It is described that impact energy absorption can be secured in a portion having low hardness.

[0006] In the case where it is impossible to perform quenching as a whole due to the large size of the press-formed product, as in the case of the body frame member, quenching is performed as shown in FIG. And cooling water pipe 31
a is moved along the longitudinal direction of the press-formed product W, and a high-frequency current is applied to the heating coil 21a to cause the passage of the press-formed product W to rapidly generate internal heat by induction heating and to be cooled by the cooling water pipe 31a. This is performed by injecting water 32a to rapidly cool the location.

[0007]

By the way, in quenching, uniform heating and cooling are required. For example, deformation due to thermal distortion may occur due to uneven heating. Above all, controlling the cooling rate is important,
If the cooling rate is low, the desired hardness and strength of the metal member cannot be obtained. When quenching is performed by induction heating by high frequency as described above, cooling is performed by cooling water from a cooling water pipe. However, as shown in FIG. 7, cooling water 32a is generated between press-formed product W and heating coil 21a. Between the cooling water 32
There is a problem that the contact condition of a becomes uneven and the quenching condition also becomes uneven.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and an object of the present invention is to provide a liquid coolant between a quenching tool and a metal molded product when quenching the metal molded product with the quenching tool. It is an object of the present invention to provide a method of manufacturing a metal member in which uniform cooling is performed and the degree of quenching is uniform without maintaining the metal member.

[0009]

A first solution of the present invention is a method for manufacturing a metal member formed of a metal material for molding, comprising: a preparing step for preparing a metal material for molding; A molding step of molding the molding metal material into a metal molded article of a predetermined shape, and a quenching step of raising the temperature of the metal molded article by a non-contact quenching tool and cooling and quenching by supplying a liquid refrigerant. The quenching step is characterized in that at least one of the metal molding and the quenching tool is vibrated so as to prevent the liquid coolant from being held between the metal molding and the quenching tool. .

[0010] According to the above, the metal molded product and / or the quenching tool vibrate at the time of quenching. Therefore, even if a liquid refrigerant is interposed between them, the surface free energy thereof is increased by the vibration, and the movement is activated. As a result, the metal member is not held between the metal molding and the quenching tool, whereby the cooling during quenching is performed uniformly, and a metal member having a uniform quenching condition can be obtained.

When an unplated metal molded product is vibrated, an oxide film formed on the surface of the metal molded product during quenching is removed by the vibration.

When the quenching is performed while holding the cast iron product in the heating furnace for a predetermined time, the quenching temperature is usually 900 to 9%.
Set to 50 ° C. On the other hand, when a press formed product of a thin steel plate is rapidly heated and rapidly cooled and quenched by induction heating by high frequency, the metal structure may not be sufficiently austenitized. The temperature is set higher than 950 ° C. and about 1000 ° C. When the quenching temperature is set high in this way, in a press-formed product whose surface is not plated,
The surface is oxidized to form a thick oxide film, and even if electrodeposition coating etc. is applied on the oxide film to improve corrosion resistance, the oxide film is poorly adhered and the coating peels off with the oxide film There is. On the other hand, in the case of a press-formed product having a plated surface, the plating may be evaporated and lost. Accordingly, from such circumstances, the obtained steel plate metal member has a remarkably poor corrosion resistance, and therefore, there is a problem that the under-type vehicle body frame member cannot be constituted by such a steel plate metal member.

In view of the above, a second solution of the present application is a method for manufacturing a metal member formed of a steel sheet, comprising a preparing step of preparing a steel sheet, and pressing the prepared steel sheet into a predetermined shape. Press forming step of forming a press-formed product by heating the press-formed product by a non-contact type quenching tool, and cooling by supplying a liquid refrigerant from the quenching tool side of the press-formed product. And a quenching step of quenching at a predetermined quenching temperature of not more than 0 ° C., wherein the steel sheet contains 0.1 to 0.2% by mass of carbon (C) and a plurality of metals,
At the quenching temperature, the metal structure has an A3 transformation point at which the metal structure is rapidly transformed into austenite, and the tensile strength is 550 MPa or less. In the quenching step, the liquid refrigerant is held between the press-formed product and the quenching tool. Vibrating at least one of the press-formed product and the quenching tool so as to prevent the quenching.

According to the above, carbon (C) is 0.1%.
Since a steel sheet having a tensile strength of 550 MPa or less is used, a metal member made of an extremely high-strength steel sheet after quenching of a press-formed product is obtained. can get.

The steel sheet has an A3 transformation point at which the metal structure rapidly transforms to austenite at a quenching temperature of 950 ° C. or less, and the quenching temperature is set at 950 ° C. or less. Formation and loss of plating are suppressed.

Further, since the press-formed product and / or the quenching tool vibrate during quenching, even if a liquid refrigerant is interposed between them, the surface free energy thereof is increased by the vibration, and the motion becomes active and the press-forming is activated. It is not held between the product and the quenching tool, whereby the cooling during quenching is performed uniformly, and a metal member made of a steel plate having a uniform quenching condition can be obtained.

When a press-formed product not plated is vibrated, an oxide film formed on the surface of the press-formed product during quenching is removed by the vibration.

A third solution of the present invention is a method for manufacturing a metal member formed of a steel sheet, comprising a preparing step of preparing a steel sheet, and pressing the prepared steel sheet into a predetermined shape to form a press-formed product. A press forming step of forming, and a predetermined temperature of 950 ° C. or lower by raising the temperature of the press-formed product by a non-contact quenching tool and supplying a liquid refrigerant from the quenching tool side of the press-formed product to cool the press-formed product. A quenching step of quenching at a quenching temperature, wherein the steel sheet contains 0.1 to 0.2% by mass of carbon (C) and a plurality of metals, and the metal structure is austenitic at the quenching temperature. The liquid refrigerant has an A3 transformation point at which the liquid refrigerant is rapidly transformed into a liquid, and has a tensile strength of 550 MPa or less, and the liquid refrigerant retains the liquid refrigerant between the press-formed product and the quenching tool. It characterized by having a surface tension to be locked.

According to the above, carbon (C) is 0.1%.
Since a steel sheet having a tensile strength of 550 MPa or less is used, a metal member made of an extremely high-strength steel sheet after quenching of a press-formed product is obtained. can get.

Further, the steel sheet is assumed to have an A3 transformation point at which the metal structure rapidly transforms to austenite at a quenching temperature of 950 ° C. or less, and the quenching temperature is set to 950 ° C. or less, so that the oxide film during quenching is formed. Formation and loss of plating are suppressed.

Furthermore, since the surface tension of the liquid refrigerant is small and the liquid refrigerant is prevented from being held between the press-formed product and the quenching tool, the cooling during quenching is uniformly performed, and the quenching condition is improved. Thus, a uniform metal member made of a steel plate can be obtained.

Here, examples of the liquid refrigerant include water mixed with a surfactant.

A fourth solution of the present application is a method for manufacturing a metal member formed of a steel sheet, comprising a preparing step of preparing a steel sheet, and pressing the prepared steel sheet into a predetermined shape to form a press-formed product. A press forming step of forming, a temperature of the press-formed product is raised by a quenching tool, and a liquid refrigerant is supplied from the side opposite to the quenching tool side of the press-formed product to cool the press-formed product to a predetermined temperature of 950 ° C. or less. A quenching step of quenching at a quenching temperature, wherein the steel sheet contains 0.1 to 0.2% by mass of carbon (C) and a plurality of metals, and the metal structure is austenitic at the quenching temperature. In the quenching step, the press-formed product is vibrated in that it has an A3 transformation point at which it rapidly transforms to 550 MPa or less.

According to the above, carbon (C) is 0.1%.
Since a steel sheet having a tensile strength of 550 MPa or less is used, a metal member made of an extremely high-strength steel sheet after quenching of a press-formed product is obtained. can get.

Further, the steel sheet is assumed to have an A3 transformation point at which the metal structure rapidly transforms to austenite at a quenching temperature of 950 ° C. or less, and since the quenching temperature is set to 950 ° C. or less, the oxide film at the time of quenching is Formation and loss of plating are suppressed.

Further, since the liquid refrigerant is supplied from the side opposite to the quenching tool side of the press-formed product, the liquid refrigerant does not intervene between the press-formed product and the quenching tool.
Moreover, by vibrating the press-formed product, the wettability of the liquid refrigerant to the press-formed product is improved, and the liquid refrigerant comes into uniform contact with the press-formed product. A metal member made of a steel plate having a uniform condition can be obtained.

When a press-formed product not plated is vibrated, an oxide film formed on the surface of the press-formed product during quenching is removed by the vibration.

In the above-mentioned second to fourth solutions, the higher the carbon (C) content of the steel sheet, the higher the strength of the steel member made after quenching.
If it is lower than the above, it is difficult to obtain a high-strength steel plate metal member having a strength after quenching of 1000 MPa or more, and if it is higher than 0.2% by mass, the strength before quenching is 55%.
It is difficult to be 0 MPa or less, and the press formability is poor, and the obtained press-formed product is brittle. In a vehicle body frame member, if a strength of 1000 MPa or more is obtained after quenching, the effects of reducing the thickness and reducing the reinforcement can be sufficiently obtained.

Further, in the second to fourth solutions, the plurality of metals contained in the steel sheet have a configuration in which manganese (Mn) has a mass content of 0.5 to 2.0 mass% with respect to the mass of the steel sheet. There may be.

The A3 transformation point of the material forming the steel sheet is mainly affected by the content of carbon (C) and the content of manganese (Mn), and as described above, the content of carbon (C) varies before and after quenching. Is limited by the strength of However, according to the above, since the content of manganese (Mn) is 0.5 to 2.0% by mass, the A3 transformation point becomes low as long as the strength of the steel sheet does not become too high. Thereby, the quenching temperature can be set low, and the formation of an oxide film and the loss of plating during quenching are more effectively suppressed.

Here, the content of manganese (Mn) is 0.1.
When the content is lower than 5% by mass, the effect of lowering the A3 transformation point by manganese (Mn) cannot be sufficiently obtained, and when the content of manganese (Mn) is higher than 2.0% by mass, manganese (Mn) becomes solid. Since it is a solution strengthening element, the strength of the steel sheet increases, and the press formability of the steel sheet deteriorates.

[0032]

As described above, according to the first solution of the present application, a metal member having a uniform quenching condition can be obtained. Also, when vibrating a metal molded product,
An oxide film formed on the surface of the metal molded product during quenching can be removed.

Further, according to the second to fourth solutions, it is possible to improve the press formability of the steel sheet and to obtain a metal member made of a steel sheet having extremely high strength after quenching the press-formed product. Can be. In addition, formation of an oxide film during quenching and loss of plating can be suppressed. Further, a metal member made of a steel plate having a uniform quenching condition can be obtained.

Further, according to the second and fourth solutions,
It is possible to remove an oxide film formed on the surface of an unplated metal molded product during quenching.

[0035]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) A method of manufacturing a vehicle body frame member (steel plate member) according to Embodiment 1 of the present invention will be described step by step.

<Preparation Step> 0.1 to 0.2% by mass of carbon (C) and 0.5 to 2.0% by mass of manganese (M
n) and a plurality of metals including Fe as a main component, and has an A3 transformation point at which a metal structure rapidly transforms to austenite at a predetermined quenching temperature of 950 ° C. or less, and has a tensile strength of 550 MPa or less. Prepare a steel plate.

<Press Forming Step> The prepared steel plate is set in a press forming machine, and the steel plate is pressed into a hat-shaped press-formed product W having a substantially trapezoidal cross section.

<Quenching Step> As shown in FIG. 1, the quenching apparatus for the press-formed product W includes a high-frequency generator 20, a cooling water supply device 30, and a molded-product vibrator 40.

The heating coil (non-contact quenching tool) 21 of the high-frequency generator 20 is formed in a U-shape, and surrounds the top surface and both inclined surfaces of the set press-formed product W. The press-formed product W is arranged and can move along the longitudinal direction.
The heating coil 21 is provided with a coil control cable 22.
Is connected to a control unit (not shown).

The cooling water pipe 31 of the cooling water supplier 30 is
It is formed in a U-shape similar to the heating coil 21,
It is arranged in parallel with the heating coil 21, and moves along the longitudinal direction of the press-formed product W following the heating coil 21. The surface of the cooling water pipe 31 facing the press-formed product W side is provided with a plurality of ejection holes for ejecting the cooling water 32 which is a liquid refrigerant.

The vibrator 40 comprises a vibrator 41 attached to a press-formed product, and a transmitting section 42 for transmitting vibration to the vibrator 41.

In the quenching of the press-formed product W using this quenching apparatus, first, the formed press-formed product W is set such that the top surface of the hat shape is on the upper side.

Next, the switch of the transmitting section 42 is turned on, and vibration is applied to the press-formed product W via the vibrator 41.

Subsequently, a high-frequency current is supplied to the heating coil 21 by turning on a control unit of the high-frequency generator 20, and the heating coil 21 is moved along the longitudinal direction of the press-formed product W as indicated by an arrow in FIG. The cooling water 32 is ejected from the cooling water pipe 31 at the same time. At this time, the portion of the press-formed product W where the heating coil 21 passes is rapidly heated to a predetermined quenching temperature of 950 ° C. or less by induction heating, and the metal structure is austenitized. When the cooling water 32 is supplied from the pipe 31, it is rapidly cooled and the metal structure becomes martensite and hardens. The setting of the quenching temperature is performed by adjusting the intensity of the high-frequency current and the moving speed of the heating coil 21 by the control unit.

According to the method of manufacturing a body frame member according to the first embodiment of the present invention, carbon (C) is reduced to 0.1 to 0.1%.
Since a steel sheet having 0.2% by mass and a tensile strength of 550 MPa or less is used, the press formability of the steel sheet is good, and after the quenching of the press-formed product W, an extremely high-strength body frame member is formed. Obtainable.

Further, the steel sheet contains 0.5 to 2.0% by mass of manganese (Mn), the A3 transformation point is lowered in a range where the strength is not too high, and the metal is hardened even at a quenching temperature of 950 ° C. or less. It is assumed that the structure rapidly transforms to austenite, and the quenching temperature is set to 950 ° C or lower.
The formation of an oxide film during quenching can be suppressed.

Further, since the press-formed product W vibrates at the time of quenching, even if the cooling water 32 is interposed between the press-formed product W and the heating coil 21, the surface free energy is increased by the vibration, and the motion is reduced. As shown in FIG. 2, the cooling water 32 is not held between them, so that the cooling during quenching is performed uniformly, and a body frame member with a uniform quenching condition can be obtained. .

The oxide film formed on the surface of the press-formed product W during quenching can be removed by the vibration.

As described above, according to the method for manufacturing a vehicle body frame member, a vehicle body frame member having a uniform quenching condition can be obtained, so that the method can be sufficiently applied to the manufacture of an under body frame member.

(Embodiment 2) A method of manufacturing a vehicle body frame member according to Embodiment 2 of the present invention will be described. In addition,
The preparation step and the press molding step are the same as those in the first embodiment, and thus the description is omitted.

<Quenching Step> As shown in FIG. 3, the quenching device for the press-formed product W is composed of a high-frequency generator 20 and a cooling water supply device 30, and the respective configurations are the same as in the first embodiment. It is. However, as a liquid refrigerant,
For example, low surface tension cooling water mixed with a surfactant is used. The same parts as those in the first embodiment are denoted by the same reference numerals.

In the quenching of the press-formed product W using the quenching apparatus, first, the formed press-formed product W is set so that the hat-shaped top surface is on the upper side.

Next, by switching on the control unit of the high-frequency generator 20, a high-frequency current is supplied to the heating coil 21, which is a quenching tool, and the heating coil 21 is press-formed as shown in FIG. The product W is moved in the direction of the arrow in the figure along the longitudinal direction of the product W, and at the same time, the cooling water 32 is jetted from the cooling water pipe 31. At this time,
The temperature of the portion of the press-formed product W through which the heating coil 21 passes rapidly rises to a predetermined quenching temperature of 950 ° C. or less by induction heating, and the metal structure becomes austenite.
After passing through, the cooling water 32 is supplied from the cooling water pipe 31 to be rapidly cooled, and the metal structure is transformed into martensite and hardened. The setting of the quenching temperature is performed by adjusting the intensity of the high-frequency current and the moving speed of the heating coil 21 by the control unit.

According to the method of manufacturing a body frame member according to the second embodiment of the present invention, the surface tension of the cooling water 32 is small, and as shown in FIG. Since the cooling water 32 is prevented from being held between the cooling water 21 and the cooling water 21, the cooling during quenching is performed uniformly, and a vehicle body frame member having a uniform quenching condition can be obtained.

In addition, it is necessary to improve the press formability of the steel sheet, to obtain an extremely high-strength body frame member after quenching, and to suppress the formation of an oxide film during quenching. The possible points are the same as in the first embodiment.

(Embodiment 3) A method of manufacturing a vehicle body frame member according to Embodiment 3 of the present invention will be described. In addition,
The preparation step and the press molding step are the same as those in the first embodiment, and thus description thereof will be omitted.

<Quenching Step> As shown in FIG. 4, the quenching device for the press-formed product W is composed of a high-frequency generator 20, a cooling water supply device 30, and a molded-product vibrator 40. The configurations of the high-frequency generator 20 and the shaping vibrator 40 are the same as those in the first embodiment. The same parts as those in the first embodiment are indicated by the same reference numerals.

The cooling water pipe 31 of the cooling water supply device 30
Is arranged on the side opposite to the heating coil 21 side of the press-formed product W, and moves along the longitudinal direction of the press-formed product W following the heating coil 21 which is a quenching tool of the high frequency generator 20. Configuration. The surface of the cooling water pipe 21 facing the press-formed product W side is provided with a plurality of ejection holes for ejecting the cooling water 32 which is a liquid refrigerant.

In the quenching of the press-formed product W using the quenching apparatus, first, the formed press-formed product W is set so that the hat-shaped top surface faces upward.

Next, a switch of a transmitter (not shown) is turned on, and vibration is applied to the press-formed product W via the vibrator 41.

Subsequently, the control unit (not shown) of the high-frequency generator 20 is turned on, so that the heating coil 21 is turned on.
4, a heating coil 21 is moved in the direction of the arrow in the figure along the longitudinal direction of the press-formed product W, and at the same time, the cooling pipe 31 is moved, as shown in FIG.
From the cooling water 32. At this time, the portion of the press-formed product W where the heating coil 21 passes is rapidly heated to a predetermined quenching temperature of 950 ° C. or less by induction heating, and the metal structure is austenitized. When the cooling water 32 is supplied from the pipe 31, it is rapidly cooled and the metal structure becomes martensite and hardens.
The setting of the quenching temperature is performed by adjusting the intensity of the high-frequency current and the moving speed of the heating coil 21 by the control unit.

According to the method of manufacturing the body frame member according to the third embodiment of the present invention, since the cooling water 32 is supplied from the opposite side of the press-formed product W from the heating coil 21 side, the press-formed product W Cooling water 3 between the heating coil 21
2 does not intervene, and by vibrating the press-formed product W, the wettability of the cooling water to the press-formed product W is improved, and the cooling water 32 uniformly contacts the press-formed product W. As a result, cooling during quenching is performed uniformly, and a body frame member having a uniform quenching condition can be obtained.

In addition, it is possible to improve the press formability of the steel sheet, to obtain an extremely high-strength body frame member after quenching, and to suppress the formation of an oxide film during quenching. This is the same as the first embodiment in that it can be removed and the oxide film formed during quenching can be removed by vibration.

(Other Embodiments) First to Third Embodiments
In the above, the body frame member which is a metal member made of a steel plate was manufactured, but the invention is not particularly limited to this. Even if a metal member made of a steel plate quenched with another press-formed product is manufactured, Alternatively, a metal member obtained by quenching a metal molded product by casting may be manufactured.

In the first embodiment, the press-formed product W is caused to vibrate. However, the present invention is not particularly limited to this. The press-formed product W is stopped and the heating coil 21 as a quenching tool is moved. You may make it vibrate, and you may make it vibrate both the press-formed product W and the coil 21 for a heating.

In the first to third embodiments, a non-plated steel plate is used. However, the present invention is not limited to this, and a plated steel plate may be used. In this case, the loss due to evaporation of the plating is suppressed due to the low quenching temperature.

In the first to third embodiments, quenching is performed by internally generating heat by high-frequency induction heating. However, the present invention is not limited to this. It may be one that generates heat.

Further, in the third embodiment, the heating coil 21 which is a non-contact type hardening tool is used. However, the present invention is not limited to this, and a contact type hardening tool may be used.

[0070]

EXAMPLES (Test Evaluation Samples) The steel sheets of Examples 1 to 15 having the material compositions shown in Table 1 were used as test evaluation samples.

[0071]

[Table 1]

(Test evaluation method) <Tensile strength before and after quenching> For each of the steel sheets of Examples 1 to 15, the tensile strength before and after quenching was measured. For the measurement, a JIS No. 5 test piece was cut out from each steel sheet, and the test piece was
This was performed by performing a tensile test at a speed of m / min. The quenching of the test pieces was performed by induction heating each test piece to 950 ° C. with high frequency and applying cooling water. Tensile strength after quenching was “○” for 1000 MPa or more, 1
Those with less than 000 MPa were evaluated as "x".

<A3 Transformation Point> For each of the steel sheets of Examples 1 to 15, the measured mass was about 30 g and the heating rate was 0.033 ° C. /
The endotherm during transformation was observed by differential thermal analysis as sec.
The temperature at that time was taken as A3 transformation point.

<Corrosion Resistance> The steel sheet of Example 12 had a basis weight of 60 g /
which underwent hot-dip galvanizing m ^{2, and} the ones who underwent galvanized steel sheet of Example 13 at a basis weight 20 g / m ^2,
The steel sheet of Example 13 was subjected to hot-dip galvanizing with a basis weight of 30 g / m ² , the steel sheet of Example 13 was subjected to hot-dip galvanizing with a basis weight of 60 g / m ² , and the steel sheet of Example 13 with a basis weight of 90 g / m 2 Five kinds of test pieces 1 to 5 each of which was subjected to induction heating (quenching temperature 950 ° C.) by high frequency and quenching by applying cooling water to each of those subjected to hot-dip galvanizing in ²
Was prepared. Then, for each of the above test pieces 1 to 5, the same tensile test and salt spray test JIS as described above
A 100-hour corrosion resistance test was performed under the conditions according to Z2371. The tensile strength was evaluated as “○” when the tensile strength was 1000 MPa or more, and “×” when the tensile strength was less than 1000 MPa. The corrosion resistance was evaluated as “○” when the surface properties were not affected by the salt water, and as “X” when there was an effect.

(Test Evaluation Results) <Tensile Strength Before and After Quenching, A3 Transformation Point> Table 2 shows the A3 transformation point, the tensile strength before quenching, and the tensile strength evaluation after quenching of each of the steel sheets of Examples 1 to 15.

[0076]

[Table 2]

According to the table, it is understood that the tensile strength after quenching tends to depend on the content of carbon (C) contained in the steel sheet. That is, in Examples 1 to 8 and 12, the content of carbon (C) was less than 0.1% by mass,
While no tensile strength higher than Pa was obtained, Example 11
And 13 to 15 have a carbon (C) content of 0.1% by mass.
As described above, a tensile strength of 1000 MPa or more is obtained. In Examples 9 and 10, although the content of carbon (C) was 0.1% by mass or more, the tensile strength was 1000M.
This is considered to be because the A3 transformation point is higher than 900 ° C. and at a quenching temperature of 950 ° C., the metal structure did not sufficiently austenite.

Further, in order to obtain good press formability, it is necessary that the tensile strength before quenching is 550 MPa or less, but all conditions except for Example 11 satisfy this condition. Therefore, the tensile strength after quenching is 1000MP.
a or more and the press formability before quenching is excellent because the content of carbon (C) is 0.1% by mass or more and the tensile strength before quenching is 550 MPa or less.
3 to 15.

FIG. 5 shows the relationship between the manganese (Mn) content and A3.
This shows the relationship with the transformation point.

[0086] According to the figure, it can be seen that the A3 transformation point decreases as the content of manganese (Mn) increases. When the quenching temperature is 950 ° C., it is considered that the A3 transformation point of the steel sheet needs to be 900 ° C. or less in order to austenitize the metal structure by rapid heating. From FIG. 5, manganese (Mn) is required. It can be seen that a content of at least 1.0% by mass is necessary.

<Corrosion Resistance> Table 3 shows the evaluation results of the tensile strength and the corrosion resistance of each of the test pieces 1 to 5.

[0082]

[Table 3]

Although the test piece 1 has good corrosion resistance due to the remaining plating, the strength after quenching is less than 1000 MPa as shown in the above evaluation results (tensile strength after quenching in Example 10).

The test piece 2 has poor corrosion resistance despite being plated. This is considered to be because if the basis weight of the plating was 20 g / m ² , the plating would be lost due to evaporation during quenching, and a sufficient plating layer would not remain after quenching.

Test pieces 3 to 5 had a basis weight of plating of 30,
The corrosion resistance is 60 and 90 g / m ² , which is good.

Accordingly, as described above, in order to maintain good corrosion resistance due to plating even after quenching, the basis weight is set to 30 g / m ^{2 in} consideration of the loss due to evaporation of the plating during quenching.
It is necessary to do above.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a quenching step according to Embodiment 1 of the present invention.

FIG. 2 is a front view taken along arrow X in FIG.

FIG. 3 is an explanatory view schematically showing a quenching step according to Embodiment 2 of the present invention.

FIG. 4 is an explanatory view schematically showing a quenching step according to Embodiment 3 of the present invention.

FIG. 5 is a graph showing the relationship between the manganese (Mn) content and the A3 transformation point.

FIG. 6 is an explanatory view showing quenching of a press-formed product by conventional high-frequency induction heating.

FIG. 7 is a front view taken in the direction of arrow Y in FIG. 6;

[Explanation of symbols]

 REFERENCE SIGNS LIST 20 high frequency generator 21, 21 a heating coil 22 coil control cable 30 cooling water supply device 31, 31 a cooling water pipe 32, 32 a cooling water 40 molded product vibrator 41 vibrator 42 transmission unit W press molded product

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22C 38/00 301 C22C 38/00 301Z 38/04 38/04 (72) Inventor Katsuya Nishiguchi Aki-gun, Hiroshima 3-1 Fuchicho Shinchi Mazda Co., Ltd. (72) Inventor Yukihiro Sugimoto 3-1 Fuchumachi Shinchi, Aki-gun, Hiroshima Pref. Mazda Co., Ltd. F-term (reference) BA06 CA01 DA01 DB01 DB04 DB05 DC02 DD02 EA01

Claims (8)

[Claims] 1. A method for manufacturing a metal member formed from a molding metal material, comprising: a preparing step of preparing a molding metal material; and forming the prepared molding metal material into a metal molded product having a predetermined shape. A forming step, and a quenching step of raising the temperature of the metal molded product by a non-contact quenching tool and cooling and quenching by supplying a liquid refrigerant, wherein the quenching step includes the press-formed product and the quenching. A method for manufacturing a metal member, comprising vibrating at least one of the press-formed product and the quenching tool so as to prevent the liquid coolant from being held between the tool and the tool. 2. A method for producing a metal member formed from a steel sheet, comprising: a preparing step of preparing a steel sheet; a press forming step of pressing the prepared steel sheet into a predetermined shape to form a press-formed product; A quenching step in which the press-formed product is heated at a predetermined quenching temperature of 950 ° C. or lower by raising the temperature with a non-contact quenching tool and supplying and cooling a liquid refrigerant from the quenching tool side of the press-formed product; The steel sheet contains 0.1 to 0.2% by mass of carbon (C) and a plurality of metals, and has an A3 transformation point at which the metal structure rapidly transforms to austenite at the quenching temperature. And having a tensile strength of 550 MPa or less. In the quenching step, the liquid coolant is prevented from being held between the press-formed product and the quenching tool. Method for producing a metal member characterized by vibrating at least one of the press molded article and 該焼 insertion tool. 3. A method for producing a metal member formed of a steel sheet, comprising: a preparing step of preparing a steel sheet; a press forming step of pressing the prepared steel sheet into a predetermined shape to form a press-formed product; A quenching step in which the press-formed product is heated at a predetermined quenching temperature of 950 ° C. or less by raising the temperature with a non-contact quenching tool and supplying and cooling a liquid refrigerant from the quenching tool side of the press-formed product. The steel sheet contains 0.1 to 0.2% by mass of carbon (C) and a plurality of metals, and has an A3 transformation point at which the metal structure rapidly transforms to austenite at the quenching temperature. The liquid refrigerant has a surface tension that prevents the liquid refrigerant from being held between the press-formed product and the quenching tool. Method for producing a metal member according to claim Rukoto. 4. A method for producing a metal member formed of a steel sheet, comprising: a preparing step of preparing a steel sheet; a press forming step of pressing the prepared steel sheet into a predetermined shape to form a press-formed product; A quenching step of raising the temperature of the press-formed product by a quenching tool and quenching at a predetermined quenching temperature of 950 ° C. or less by supplying a liquid refrigerant from the opposite side of the quenched tool side of the press-formed product and cooling the same; The steel sheet contains 0.1 to 0.2% by mass of carbon (C) and a plurality of metals, and has an A3 transformation point at which the metal structure rapidly transforms to austenite at the quenching temperature. A method for producing a metal member, comprising: having a tensile strength of 550 MPa or less; and vibrating the press-formed product in the quenching step. 5. The method for manufacturing a metal member according to claim 2, wherein the plurality of metals contained in the steel sheet have a mass content of 1.0 to 2 with respect to the mass of the steel sheet. 0.0% by mass of manganese (M
n) A method for producing a metal member, the method comprising: 6. A metal member formed of a steel plate, wherein a press-formed product obtained by press-forming a steel plate into a predetermined shape is heated by a non-contact quenching tool, and is heated from the quenching tool side of the press-formed product. It is formed by quenching at a predetermined quenching temperature of 950 ° C. or less by supplying and cooling a liquid refrigerant, wherein the steel sheet contains 0.1 to 0.2% by mass of carbon (C) and a plurality of metals. At the quenching temperature, the metal structure has an A3 transformation point at which the metal structure rapidly transforms into austenite, and the tensile strength is 550 MPa or less. During the quenching, the liquid flowing between the press-formed product and the quenching tool is formed. A metal member, wherein at least one of the press-formed product and the quenching tool is vibrated so as to prevent the coolant from being retained. 7. A metal member formed of a steel plate, wherein a press-formed product obtained by press-forming a steel plate into a predetermined shape is heated by a non-contact quenching tool, and is heated from the quenching tool side of the press-formed product. It is formed by quenching at a predetermined quenching temperature of 950 ° C. or less by supplying and cooling a liquid refrigerant, wherein the steel sheet contains 0.1 to 0.2% by mass of carbon (C) and a plurality of metals. At the same time, the metal structure has an A3 transformation point at which the metal structure is rapidly transformed into austenite at the quenching temperature, and the tensile strength is 550 MPa or less. The liquid refrigerant is supplied between the press-formed product and the quenching tool. A metal member having a surface tension that prevents retention of the liquid refrigerant. 8. A metal member formed of a steel plate, wherein a press-formed product obtained by press-forming a steel plate into a predetermined shape is heated by a quenching tool, and the press-formed product is heated from a side opposite to the quenching tool side. It is formed by quenching at a predetermined quenching temperature of 950 ° C. or less by supplying and cooling a liquid refrigerant, wherein the steel sheet contains 0.1 to 0.2% by mass of carbon (C) and a plurality of metals. A metal structure having an A3 transformation point at which the metal structure rapidly transforms into austenite at the quenching temperature, a tensile strength of 550 MPa or less, and the press-formed product being vibrated during the quenching. Element.