JP6375048B1 - Rolled joint - Google Patents

Abstract

An object of the present invention is to provide a rolled joined body that exhibits a high Erichsen value even when the thickness is relatively large and is excellent in forming processability. A rolled joined body composed of a stainless steel layer and a metal layer different from stainless steel, having a thickness T of 0.2 mm or more and 3 mm or less, and a ratio PSUS of the thickness TSUS of the stainless steel layer to the thickness T; The relationship with the peak half-value width FWHM200 indicating the crystal plane orientation (200) obtained when X-ray diffraction measurement is performed on the stainless steel layer side satisfies the following formula. FWHM200 ≦ 0.0057PSUS + 0.4 [Selection] Figure 1

Description

  The present invention relates to a rolled joined body.

  Metal materials are used in various fields, and are used, for example, as press-molded parts for electronic devices such as mobile electronic device casings. These metal materials are required to have high press workability. As such a metal material, in addition to a metal material made of a single metal, a rolled joined body (metal laminate material, clad material) in which two or more kinds of metal plates or metal foils are laminated is known. A rolled joined body is a highly functional metal material having composite characteristics that cannot be obtained by a single material. For example, a rolled joined body in which stainless steel and aluminum are laminated is being studied.

  Here, a metal part for electronic equipment using a rolled joined body is generally formed by press working. Press processing is broadly classified into shear processing, bending processing, and drawing processing. Among them, the casing is formed by drawing processing. The drawing process is difficult to perform even during the press process because the rolled joined body is fixed to a die and a punch is pressed into a hole provided in the die to form a container shape. When drawing is performed, the stretch formability of the rolled joined body is one of important parameters, and high stretch formability is required.

  As a conventional rolled joined body (metal laminate material, clad material) excellent in forming processability, Patent Document 1 has a two-layer structure of a stainless steel layer / aluminum layer and has a tensile strength TS (MPa) of 200 ≦ A metal laminate material in which TS ≦ 550, the elongation EL is 15% or more, and the surface hardness Hv of the stainless steel layer is 300 or less is disclosed.

International Publication No. 2017/057665

  The rolled joined body described in Patent Literature 1 has a specific range of tensile strength, elongation, and surface hardness of the stainless steel layer, so that the overhang height (Erichsen value) by the Erichsen test is 6.0 mm or higher. It is to get sex. However, the rolled joined body according to Patent Document 1 is a rolled joined body having a thin thickness used for a heat radiating member or the like of an electronic device. For example, 0.4 mm or more for a three-layer material, and 0.2 for a two-layer material. There has been insufficient study on a rolled joined body having a thickness suitable for a housing that is 3 mm or more.

  In the rolled joined body, the greater the thickness, the higher the reduction force required during the rolling joining, so that the increase in the hardness of the stainless steel layer or the like is large, and the control of the hardness is difficult as the thickness is increased. And, as the hardness is higher, the elongation generally decreases, so it is difficult to obtain a rolled joined body having the moldability required for the housing.

  Therefore, in view of the above-described conventional situation, the present invention provides a rolled joined body that exhibits a high Erichsen value even when the thickness is relatively large and that is excellent in forming processability, and a method for manufacturing the same.

  As a result of intensive studies by the present inventors in order to solve the above-mentioned problems, it became clear that the texture (particle size, orientation, strain) of the stainless steel layer in the rolled joined body affects the elongation characteristics of the rolled joined body. Furthermore, the inventors have found that when the texture and the thickness ratio of the stainless steel layer satisfy a specific relationship, the moldability required for the housing can be obtained, and the invention has been completed. That is, the gist of the present invention is as follows.

(1) A rolled joined body composed of a stainless steel layer and a metal layer different from stainless steel,
Thickness T is 0.2 mm or more and 3 mm or less,
The ratio _{P SUS} thickness _{T SUS} of the stainless steel layer to said thickness T, the relationship between the half width _{FWHM 200} of the peak at lattice orientation (200) of the crystals obtained when the stainless steel layer side was measured X-ray diffraction However, the rolled joined body satisfies the following formula.
FWHM ₂₀₀ ≦ 0.0057P _SUS +0.4
(2) The rolled joined body according to (1), wherein the metal layer different from the stainless steel is a metal layer selected from the group consisting of aluminum, an aluminum alloy, and copper.
(3) The rolled joined body according to the above (1) or (2) for a housing for electronic equipment.
(4) A casing for electronic equipment using the rolled joined body according to (1) or (2) above.

  According to the present invention, it is possible to obtain a rolled joined body having a relatively large thickness and a high formability such that an overhang height by an Erichsen test is 7 mm or more. This rolled joined body can be suitably used as a member for a casing of various electronic devices such as mobile electronic devices by utilizing excellent molding processability.

It is a figure which shows typically the cross section of one Embodiment of the rolling joined body which concerns on this invention. It is a graph showing the relationship between the half width _{FWHM 200} of the peak indicating the thickness of the stainless steel layer ratio _{P SUS} and plane orientation (200). It is a graph showing the relationship between the half width _{FWHM 200} of the peak indicating the thickness of the stainless steel layer _{T SUS} and surface orientation (200). It is a graph which shows the relationship between the ratio _PSUS of the thickness of a stainless steel layer, and the surface hardness of a stainless steel layer. 1 is a perspective view showing a first embodiment of an electronic device casing according to the present invention. It is a section perspective view in the X-X 'direction of a 1st embodiment of a case for electronic equipment concerning the present invention.

  Hereinafter, the present invention will be described in detail.

I. Rolled bonded body An embodiment of a rolled bonded body according to the present invention will be described with reference to FIG. As shown in FIG. 1, the rolling joined body 1 of this embodiment is comprised from the stainless steel (SUS) layer 10 and the metal layer 20 different from stainless steel.

  The stainless steel used for the stainless steel layer 10 is not particularly limited, and plate materials such as SUS304, SUS201, SUS316, SUS316L, and SUS430 can be used.

  The metal which comprises the metal layer 20 different from stainless steel can be suitably selected according to the use of the rolling joined body, and the target characteristic. Specifically, aluminum, an aluminum alloy, copper, a copper alloy, magnesium, a magnesium alloy, etc. are mentioned. In particular, a metal selected from the group consisting of aluminum, an aluminum alloy, and copper is preferably used. By rolling and joining these metals to the stainless steel layer, the heat dissipation and light weight of the rolled joined body can be improved. For example, a rolled joined body suitable for a casing of a mobile electronic device can be obtained.

  As an aluminum alloy, an aluminum alloy plate material containing at least one additive metal element selected from Mg, Mn, Si and Cu as a metal element other than aluminum with a total content of additive metal elements exceeding 1 mass%. Can be used.

  For example, as an aluminum alloy, an Al—Cu based alloy (2000 series), an Al—Mn based alloy (3000 series), an Al—Si based alloy (4000 series), an Al—Mg based alloy (5000 series) specified in JIS, Al-Mg-Si alloys (6000 series) and Al-Zn-Mg alloys (7000 series) can be used. From the viewpoint of press formability, strength, and corrosion resistance, 3000 series, 5000 series, 6000 series, and 7000 series. In particular, a 5000 series aluminum alloy is more preferable from the viewpoint of balance and cost. The aluminum alloy preferably contains 0.3% by mass or more of Mg.

  As aluminum, a pure aluminum plate material having a total content of additive metal elements other than aluminum of 1% by mass or less can be used. As pure aluminum, for example, 1000 series pure aluminum prescribed in JIS can be used. The total content of additive metal elements other than aluminum in pure aluminum is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and particularly preferably 0.15% by mass or less. is there.

  As the copper, a copper plate material having a total content of additive metal elements other than copper of 1% by mass or less can be used. Specifically, a plate material such as C1100 can be used. An example of a copper alloy is Corson copper.

  The thickness T of the rolled joined body 1 is not particularly limited, and is usually 0.2 mm or more and 3 mm or less, preferably 0.3 mm or more and 2.2 mm or less, and particularly preferably 0.4 mm or more and 1.5 mm or less. Here, the thickness T of the rolled joined body 1 refers to the total thickness of the stainless steel layer 10 and the metal layer 20 different from stainless steel. The thickness T of the rolled bonded body is an average value of measured values obtained by measuring the thickness at any 30 points on the rolled bonded body 1 with a micrometer or the like.

The thickness _{T SUS} stainless layer 10 is applicable as long as usually 0.01mm or more, the lower limit in view of drawing formability and strength, preferably at least 0.045 mm, more preferably 0.05mm or more. The upper limit is not particularly limited, but if it is too thick for the metal layer 20 different from stainless steel, the light weight and heat dissipation may be reduced. _Therefore , _TSUS is preferably 0.6 mm or less, more preferably 0.00. It is particularly preferably 5 mm or less, and more preferably 0.4 mm or less from the viewpoint of weight reduction. Further, from the viewpoint of ensuring heat dissipation of the rolled joined body 1, the stainless steel layer 10 is preferably thinner than the metal layer 20 different from stainless steel. Specifically, the ratio _{P SUS} thickness _{T SUS} stainless layer 10 to the thickness T of preferably 5% or more and 70% or less, more preferably 60% or less than 7%. More preferably, it is 15% or more and 50% or less. The thickness _TSUS of the stainless steel layer 10 in the rolled joined body 1 was obtained by obtaining an optical micrograph of a cross section of the rolled joined body 1 and measuring the thickness of the stainless steel layer 10 at any 10 points in the optical micrograph. The average value. In the production of the rolled joined body, since the stainless steel plate of the material is joined at a predetermined reduction rate, the thickness of the stainless steel layer of the rolled joined body becomes thinner than the stainless steel plate of the material before joining.

The rolling assembly 1 of this embodiment, the ratio _{P SUS} thickness _{T SUS} stainless layer 10 to the thickness T, the plane orientation of the crystal obtained stainless layer 10 side as measured X-ray diffraction (200) The relationship with the half-value width FWHM _{200 of the} peak shown satisfies the following formula. The peak indicating the plane orientation (200) is a peak appearing at 2θ = 48 to 52 ° when the stainless steel layer 10 is measured 2θ / θ at a tube voltage: 45 kV, a tube current: 200 mA, and a radiation source: CuKα. Yes, the full width at half maximum FWHM ₂₀₀ refers to the peak width (°) at a position half the height H of the peak (H / 2).
FWHM ₂₀₀ ≦ 0.0057P _SUS +0.4

By satisfying the above formula, the state of the crystal grains in the stainless steel layer 10 is optimized in relation to the thickness ratio _PSUS of the stainless steel layer 10, and the thickness of the rolled joined body 1 is relatively large (0.2 mm or more and 3 mm or less). ), It is possible to obtain a rolled joined body 1 having excellent formability.

  On the other hand, at 2θ = 43 to 45 ° in the immediate vicinity of the (111) diffraction peak, a peak that is considered to depend on the processing degree of stainless steel is likely to appear, and the result of the (111) diffraction peak becoming broad due to the influence of this peak. It was found that it was difficult to isolate the diffraction peak, and it was difficult to identify the half width derived from (111). Further, (220) and (311) are not affected by the peak depending on the degree of processing like (111), but the original intensity of the crystal is lower than that of (111) and (200), and the diffraction peak is low. The correlation between the half width and the thickness ratio could not be obtained because it was influenced by the strength of the background. On the other hand, regarding the peak of (200), it was found that high moldability can be obtained when the half width and the thickness ratio satisfy the relationship of the above formula.

  That is, when the thickness is relatively large, the effect of improving the formability by increasing the thickness can be obtained. In addition, the present inventors have found a problem that the hardness increases due to the introduction of processing strain and a decrease in elongation occurs, and as a result, it is difficult to obtain a rolled joined body having a formability required for a casing. Focusing on the half-value width as a parameter of the stainless steel layer after joining, which also reflects the effect at the time of joining, among others, the moldability is optimized by controlling the half-value width of the (200) plane and the thickness ratio of the stainless steel layer. It was found that a rolled joined body having excellent formability can be obtained by satisfying the above formula. Specifically, a high forming workability is obtained in which the overhang height (Ericsen value) of the rolled joined body 1 by an Ericksen test is 7.0 mm or more, preferably 8.0 mm or more. Here, the overhang height by the Eriksen test can be measured according to JIS Z 2247 (Eriksen test method) using, for example, a mechanical Erichsen tester ESM-1 (CAP 2 mm, manufactured by Tokyo Henki Tester Co., Ltd.). it can.

Moreover, the present inventors further satisfy the following relational expression with respect to the half width FWHM ₂₀₀ of the peak of the (200) plane and the thickness _TSUS (mm) of the stainless steel layer, when the rolled joined body satisfying the above relational expression is satisfied. Found that is preferred. Thereby, the moldability of a rolling joined body improves more.
FWHM ₂₀₀ ≦ 0.571T _SUS +0.4

  In the rolled joined body 1 according to the present embodiment, the surface hardness Hv of the stainless steel layer 10 is appropriately set in consideration of the balance between the formability of the rolled joined body and the scratch resistance. In the present invention, the surface hardness Hv can be measured according to JIS Z 2244 (Vickers hardness test-test method) using, for example, a micro Vickers hardness meter (load 200 gf).

  Furthermore, the rolled joined body 1 according to the present embodiment preferably has a peel strength (also referred to as 180 ° peel strength or 180 ° peel strength) as an index of adhesion strength of 60 N / 20 mm or more, and excellent drawing processing. In order to obtain property, it is more preferably 80 N / 20 mm or more, and particularly preferably 100 N / 20 mm or more.

  The peel strength of the rolled bonded body 1 is such that a test piece having a width of 20 mm is produced from the rolled bonded body 1 and the stainless steel layer 10 and the metal layer 20 different from stainless steel are partially peeled off, and then the thick film layer side or the hard layer side is fixed. The force required to peel off the other layer when it is pulled 180 ° opposite to the fixed side (unit: N / 20 mm).

  In a rolled joined body having high peel strength, one layer can follow the other layer during drawing, and any layer can be processed without breaking.

  The rolled joined body 1 preferably has high drawability and a limit drawing ratio of 1.20 or more. More preferably, it is 1.63 or more, More preferably, it is 1.83 or more. The limit drawing ratio of the rolled joined body is the maximum blank that can be squeezed without rupture in one drawing at the drawing ratio D / d of the ratio of the blank diameter D to the cylinder diameter d in the cylinder drawing process. It refers to the value of Dmax / d when the diameter is Dmax.

  In the rolled joined body 1 of the present embodiment, the elongation by a tensile test is preferably 35% or more, more preferably 40% or more, for a test piece having a width of 15 mm. Thereby, favorable press workability is obtained. Elongation by a tensile test can be measured using, for example, a test piece of a tensile strength test described later according to the measurement of elongation at break described in JIS Z 2241 or JIS Z 2201.

  The rolled joined body 1 preferably has a tensile strength of 3000 N or more according to a tensile test with a test piece width of 15 mm. From the viewpoint of having sufficient strength and press workability, it is more preferably 3500 N or more. Here, the tensile strength refers to the maximum load in the tensile test. Tensile strength can be measured according to JIS Z 2241 or JIS Z 2201 (metal material tensile test method), for example, using a Tensilon universal material testing machine RTC-1350A (manufactured by Orientec Co., Ltd.). The width of 15 mm of the test piece indicates the specification of the special test piece No. 6 in JIS Z 2201. In JIS Z 2241, for example, the specification of test piece 5 can be used. Here, when the tensile strength in the No. 6 test piece is converted into the tensile strength in the No. 5 test piece, the width of the test piece may be multiplied by 25 mm / 15 mm, that is, about 1.66 times. It ’s fine.

II. Manufacturing method of rolled bonded body When manufacturing the rolled bonded body 1, a stainless steel plate and a metal plate different from stainless steel are prepared, and these are cold rolled bonded, warm rolled bonded, surface activated bonded, etc. It can be performed by bonding to each other by various methods. Moreover, it is preferable to perform stabilization heat processing after joining. Warm rolling joining is a method of rolling joining while applying heat above the recrystallization temperature of the joining material, and it can be joined with lower force than cold rolling joining, but it generates an intermetallic compound at the joining interface. Easy to do. Therefore, attention should be paid to the selection of the heating temperature and heating time conditions so as not to generate intermetallic compounds.

  Moreover, in cold rolling joining, after brushing etc. on the joining surface of a stainless steel plate material and a metal plate material different from stainless steel, they are superposed and joined together while cold rolling, and further subjected to annealing treatment. Thus, a rolled joined body can be manufactured. The cold rolling process may be performed in multiple stages, and temper rolling may be added after the annealing treatment. In this method, rolling joining is performed in a range of 20 to 90% as a final reduction ratio. When manufacturing by the cold bonding method, considering the rolling reduction, the thickness of the original plate is 0.0125 mm to 6 mm, preferably 0.056 mm to 5 mm, more preferably 0.063 mm to 4 mm, Is different from 0.063 mm to 25 mm, preferably 0.13 mm to 17 mm, more preferably 0.25 mm to 11 mm.

  Furthermore, in warm rolling joining, after performing brush polishing or the like on the joint surfaces as in cold rolling joining, both or one side is heated to 200 to 500 ° C., overlaid, warm rolled and joined. can do. In this method, the final rolling reduction is about 15 to 40%. In the case of producing by a warm joining method, considering the rolling reduction, the thickness of the original plate is 0.012 mm to 1 mm, preferably 0.053 mm to 0.83 mm, more preferably 0.059 mm to 0.003 mm for a stainless steel plate material. The metal plate material different from 067 mm and stainless steel is 0.059 mm to 4.2 mm, preferably 0.19 mm to 2.8 mm, more preferably 0.24 mm to 1.8 mm.

  As a method of manufacturing the rolled joined body 1, it is preferable to join by surface activated joining from the viewpoint that it is easy to suppress processing strain entering the stainless steel layer during joining. Preferred embodiments are as follows. That is, a step of preparing a stainless plate and a metal plate different from stainless steel (hereinafter referred to as “the other metal plate”), sputter-etching the joining surface of the stainless plate and the other metal plate, and the sputter-etched surfaces A step of joining by pressure welding so that the rolling reduction of the stainless steel layer is 0% or more and 25% or less, and a batch heat treatment of 200 ° C. or more and 500 ° C. or less or a continuous heat treatment at 300 ° C. or more and 890 ° C. or less. It can manufacture by the method including the process to perform.

  The stainless steel plate that can be used is preferably an annealed material (BA material), a 1 / 2H material or the like from the viewpoint of moldability, but is not limited thereto.

  The thickness of the stainless steel plate before joining is usually applicable as long as it is 0.01 mm or more, and the lower limit is preferably 0.045 mm or more from the viewpoint of drawability and strength and handling properties when a rolled joined body is used. More preferably, it is 0.05 mm or more. The upper limit is not particularly limited, but if it is too thick with respect to the other metal layer, elongation and drawability when formed into a rolled joined body may be lowered. It is particularly preferably 0.53 mm or less from the viewpoint of 67 mm or less and further weight reduction. The thickness of the stainless steel plate before joining can be measured with a micrometer or the like, and means an average value of thicknesses measured at 10 points randomly selected from the surface of the stainless steel plate.

  The other metal plate to be joined to the stainless steel plate can be appropriately selected from various metal plates according to the type of metal. The thickness before joining the other metal plate is usually 0.05 mm or more, and the lower limit is preferably 0.1 mm or more, and more preferably 0.2 mm or more. The upper limit is usually 3.3 mm or less, preferably 2.3 mm or less, more preferably 1.5 mm or less from the viewpoint of weight reduction and cost. The thickness of the other metal plate before joining can be determined in the same manner as the stainless steel plate.

  Specifically, in the sputter etching process, the stainless steel plate and the other metal plate are prepared as a long coil having a width of 100 mm to 600 mm, and the stainless steel plate having the joining surface and the other metal plate are grounded respectively. A glow discharge is generated by applying an alternating current of 1 MHz to 50 MHz to another electrode that is insulated and supported, and the area of the electrode exposed in the plasma generated by the glow discharge is defined as the other electrode. The area is 1/3 or less. During the sputter etching process, the grounded electrode takes the form of a cooling roll, which can prevent the temperature of each conveying material from rising.

In the sputter etching process, the adsorbed material on the surface is completely removed by sputtering the surface where the stainless steel plate and the other metal plate are joined with an inert gas in a vacuum, and part or all of the oxide film on the surface is removed. Remove. The oxide film does not necessarily need to be completely removed, and a sufficient bonding force can be obtained even if it remains partially. By leaving a part of the oxide film, it is possible to significantly reduce the sputter etching processing time as compared with the case where the oxide film is completely removed, and to improve the productivity of the rolled joined body. As the inert gas, argon, neon, xenon, krypton, or a mixed gas containing at least one of these can be used. The adsorbate on the surface of both the stainless steel plate and the other metal plate can be completely removed with an etching amount of about 1 nm (in terms of SiO ₂ ).

For example, in the case of a single plate, the sputter etching process for a stainless plate can be performed under a vacuum, for example, with a plasma output of 100 W to 1 kW for 1 to 50 minutes, and for a long material such as a line material, for example. Under vacuum, for example, it can be performed at a plasma output of 100 W to 10 kW and a line speed of 1 m / min to 30 m / min. The degree of vacuum at this time is preferably higher in order to prevent re-adsorbed substances on the surface, but may be, for example, 1 × 10 ⁻⁵ Pa to 10 Pa. In the sputter etching process, the temperature of the stainless steel plate is preferably maintained at room temperature to 150 ° C. from the viewpoint of preventing softening of the other metal plate.

  A stainless steel plate with a part of the oxide film remaining on the surface can be obtained by setting the etching amount of the stainless steel plate to 1 nm to 10 nm, for example. If necessary, the etching amount may exceed 10 nm.

The conditions of the sputter etching process for the other metal plate are appropriately set depending on the type of metal. For example, the sputter etching process for an aluminum alloy plate can be performed, for example, in the case of a single plate under a vacuum, for example, with a plasma output of 100 W to 1 kW for 1 to 50 minutes, and for example, a long material such as a line material In this case, it can be performed at a plasma output of 100 W to 10 kW and a line speed of 1 m / min to 30 m / min. The degree of vacuum at this time is preferably higher in order to prevent re-adsorption on the surface, but it may be 1 × 10 ⁻⁵ Pa to 10 Pa.

  The aluminum alloy plate in which a part of the surface oxide film remains can be obtained by setting the etching amount of the aluminum alloy plate to, for example, 1 nm to 10 nm. If necessary, the etching amount may exceed 10 nm.

  The joining surface of the stainless steel plate sputter-etched as described above and the other metal plate is pressed by, for example, roll pressing so that the rolling reduction of the stainless steel layer is 0% or more and 25% or less. And the other metal plate are joined.

  The rolling reduction of the stainless steel layer is preferably 0% or more and 10% or less, more preferably 0% or more and 8% or less. When the upper limit of the rolling reduction of the stainless steel layer is within the above range, work hardening of the stainless steel layer due to the introduction of processing strain can be suppressed, so that it is possible to suppress a decrease in elongation and a press workability. Since the stainless steel layer has a small effect of softening due to the heat treatment after the rolling joining, it is necessary to control the influence of work hardening by the rolling reduction during the rolling joining.

  The total rolling reduction of the rolled joined body is preferably 0% or more and 25% or less, and more preferably 0% or more and 15% or less. More preferably, it is 10% or less. When the rolling reduction of the rolled bonded body is 25% or less, the stainless steel layer does not have processing strain excessively and has sufficient strength and elongation, so that it is easy to obtain a rolled bonded body with high press workability. Moreover, since the thickness of each layer can be kept uniform to some extent, high press workability is expressed. That is, if a thin portion occurs during rolling joining, a load is likely to be applied locally during press working, and there is a risk of breakage. The rolling reduction of the rolled joined body is determined from the total thickness of the stainless steel plate and the other metal plate, which are the materials before joining, and the final thickness of the rolled joined body. That is, the rolling reduction of the rolled joined body is expressed by the following formula: (total thickness of the stainless steel plate before joining and the other metal plate-final thickness of the rolled joined body) / the stainless steel plate before joining and the other metal plate. It is determined by the total thickness.

  The rolling line load of the roll pressure welding is not particularly limited, and can be appropriately set so as to achieve a predetermined reduction rate for the stainless steel layer. For example, it can be set in the range of 1.0 tf / cm to 10.0 tf / cm. For example, when the roll diameter of the pressure welding roll is 100 mm to 250 mm, the rolling line load of the roll pressure welding is preferably 1.5 tf / cm to 5.0 tf / cm, more preferably 1.6 tf / cm to 4.0 tf / cm. cm. However, when the roll diameter becomes large or the stainless steel plate before joining or the thickness of the other metal plate is thick, it may be necessary to increase the rolling line load to secure the pressure. It is not limited to a numerical range.

  The temperature at the time of joining is not specifically limited, For example, it is normal temperature-150 degreeC.

  Joining should be performed in a non-oxidizing atmosphere, for example, an inert gas atmosphere such as Ar, in order to prevent a reduction in bonding strength between the stainless steel plate and the other metal plate due to re-adsorption of oxygen. Is preferred.

  The rolled joined body obtained by joining the stainless steel plate and the other metal plate as described above is subjected to heat treatment. The heat treatment can improve the adhesion between the layers. In addition, when the other metal plate is aluminum alloy etc., heat processing can serve as annealing of an aluminum alloy layer.

  For example, in the case of batch heat treatment, the heat treatment temperature is 200 ° C. or more and 500 ° C. or less, preferably 200 ° C. or more and 400 ° C. or less. For example, in the case of continuous heat treatment, it is 300 ° C. or higher and 890 ° C. or lower, preferably 300 ° C. or higher and 800 ° C. or lower. By setting the heat treatment temperature within this range, the peel strength of the rolled joined body is as high as 60 N / 20 mm or more, and as a result, the moldability is improved. This heat treatment temperature is not softened because it is in the non-recrystallization temperature range for stainless steel. In this embodiment, the peel strength of the rolled joined body is significantly improved by controlling the rolling reduction ratio of the stainless steel layer during the joining and the heat treatment temperature within a predetermined range, and as a result, the moldability is improved. The heat treatment temperature refers to the temperature of the rolled joined body that undergoes the heat treatment.

  In this heat treatment, at least a metal element (for example, Fe, Cr, Ni) contained in the stainless steel is thermally diffused into a metal layer different from the other stainless steel. Further, a metal element contained in stainless steel and a metal element contained in a metal layer different from stainless steel may be thermally diffused with each other.

  The heat treatment time can be appropriately set according to the heat treatment method (batch heat treatment or continuous heat treatment), the heat treatment temperature, and the size of the rolled joined body to be heat treated. For example, in the case of batch heat treatment, after the temperature of the rolled joined body reaches a predetermined temperature, the rolled joined body is kept soaked for 0.5 to 10 hours, preferably kept soaked for 2 to 8 hours. If no intermetallic compound is formed, there is no problem even if batch heat treatment is performed for 10 hours or more. In the case of continuous heat treatment, the rolled joined body is kept soaked for 20 seconds to 5 minutes after the temperature of the rolled joined body reaches a predetermined temperature. The heat treatment time refers to the time after the rolled joined body to be heat treated reaches a predetermined temperature, and does not include the temperature rise time of the rolled joined body. As for the heat treatment time, for example, for a small material of about A4 size (paper size), about 1 to 2 hours is sufficient for batch heat treatment, but a long material such as a coil material having a width of 100 mm or more and a length of 10 m or more, etc. For large materials, batch heat treatment requires about 2-8 hours.

III. Application of Rolled Bonded Body The rolled bonded body according to the present embodiment can be used as various press-formed parts. In particular, when the thickness is large, the strength is high and the molding processability is high, so that it can be suitably used as a casing for electronic devices, especially as a casing for mobile electronic devices (mobile terminals). it can. In the case, the processing on the outer surface side is stricter. Especially, processing to a case formed with a metal layer made of aluminum alloy or pure aluminum as the inner surface side and a stainless steel layer as the outer surface side or a case with a thin stainless steel layer is made of stainless steel. Although breakage of the layer is likely to occur, since the stainless steel layer has good workability by following the other metal layer by using the rolled joined body according to this embodiment, the stainless steel layer does not break. Can be obtained. In addition, when it is set as a housing | casing, the process for the purpose of discoloration suppression and a decoration may be performed, and the use of a rolling joined body is not limited to the said housing | casing.

  The housing for electronic devices preferably includes the rolled joined body of the present invention on the back surface and / or the side surface.

  1st Embodiment of the housing | casing for electronic devices using the rolling joined body of this invention is shown in FIG.5 and FIG.6. FIG. 5 is a perspective view showing a first embodiment of an electronic device casing using the rolled bonded body of the present invention, and FIG. 6 is an electronic device casing using the rolled bonded body of the present invention. It is a section perspective view in the XX 'direction of a 1st embodiment. The casing 5 for electronic equipment can include the rolled joined body of the present invention, which includes a back surface 50 and a side surface 51, and the back surface 50 and the side surface 51 or a part thereof includes a stainless steel layer and a metal layer different from stainless steel. . Here, the back surface refers to a surface on the opposite side to a side on which a display unit (this display, not shown) is provided in a housing constituting an electronic device (mobile terminal) such as a smartphone. Moreover, you may laminate | stack the metal material different from a rolling joined body, a plastic material, etc. inside the housing | casing 5 for electronic devices. In addition, when the case 5 for electronic devices includes a rolling joined body in the back surface 50, the whole or a part of the back surface 50 (for example, 2 cm x 2 cm or more, for example, 25 mm x 25 mm as shown by the plane part A of FIG. 5). As long as the flat surface portion of the material satisfies the above-mentioned characteristics described for the rolled joined body. In addition, although the housing | casing 5 for electronic devices is a structure containing the rolling joining body in the back surface 50, it is not limited to this structure depending on the structure of an electronic device, and the back surface 50 and the side surface 51 are from a rolling joining body. The structure which comprises may be sufficient, and the structure which contains a rolling joined body in the side surface 51 may be sufficient.

  Next, a second embodiment of an electronic device casing using the rolled joined body of the present invention will be described. In the present embodiment, an electronic device casing, which is a center frame, shows an electronic device structure sandwiched between a display unit such as glass or resin and a back surface. The electronic device casing is provided on a side surface and the side surface. It is comprised from the connected internal reinforcement frame (it comprises the back in the housing | casing for electronic devices). The casing for electronic equipment can include the rolled joined body of the present invention in which the side surface and the internal reinforcing frame or a part thereof are made of a stainless steel layer and a metal layer different from stainless steel. Here, the internal reinforcement frame means a support plate that is located inside an electronic device such as a smartphone and serves as a support for improving rigidity of the entire electronic device and mounting components such as a battery and a printed board. . The internal reinforcement frame usually has holes for connection and assembly. The hole can be opened by, for example, a press. In the present embodiment, the side surface and the internal reinforcing frame can be integrally formed, but the present invention is not limited to this, and the side surface and the internal reinforcing frame may not be integrated. Moreover, you may apply a rolling joined body only to a side surface. Note that the electronic device casing of the present embodiment can be modified as appropriate according to the structure of the electronic device, similarly to the electronic device casing 5, and is limited to the structure described above. It is not something.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example and a reference example, this invention is not limited to these Examples.

Example 1
A rolled joined body was produced by a surface activated joining method. SUS304 BA having a thickness of 0.05 mm was used as the stainless steel plate, and aluminum alloy A5052 having a thickness of 0.8 mm was used as the aluminum plate. Sputter etching was performed on SUS304 and A5052. Sputter etching for SUS304 is performed under conditions of 0.3 Pa, plasma output 700 W, 12 minutes, and sputter etching for A5052 is performed under conditions of 0.3 Pa, plasma output 700 W, 12 minutes. did. SUS304 and A5052 after the sputter etching treatment are made at a normal temperature, with a rolling roll diameter of 100 mm to 250 mm, a rolling line load of 0.5 tf / cm to 5.0 tf / cm, and a reduction rate of 0% to 5% of the stainless steel layer. Then, they were joined by roll pressure welding to obtain a rolled joined body of SUS304 and A5052. This rolled joined body was subjected to batch heat treatment at 300 ° C. for 1 hour.

(Examples 2-6, Comparative Examples 1-3)
The steel type, tempering and thickness of the original plate, and / or the type and thickness of the original aluminum plate were changed, and the pressure applied at the time of joining was changed to a predetermined value in the same manner as in Example 1, The rolled joined bodies of Examples 2 to 6 and Comparative Examples 1 to 3 were obtained.
In Example 2, 316L 1 / 2H having a thickness of 0.05 mm was used as the stainless steel plate, and aluminum alloy A5052 having a thickness of 0.8 mm was used as the aluminum plate.
In Example 3, 304 1 / 2H having a thickness of 0.1 mm was used as the stainless steel plate, and aluminum alloy A5052 having a thickness of 0.8 mm was used as the aluminum plate.
In Example 4, 304 1 / 2H having a thickness of 0.1 mm was used as the stainless steel plate, and aluminum alloy A5052 having a thickness of 0.8 mm was used as the aluminum plate.
In Example 5, 304 1 / 2H having a thickness of 0.1 mm was used as the stainless steel plate, and aluminum A1050 having a thickness of 0.8 mm was used as the aluminum plate.
In Example 6, 304 1 / 2H having a thickness of 0.2 mm was used as the stainless steel plate, and aluminum alloy A5052 having a thickness of 0.8 mm was used as the aluminum plate.
In Comparative Example 1, 304 3 / 4H having a thickness of 0.1 mm was used as the stainless steel plate, and aluminum alloy A5052 having a thickness of 0.8 mm was used as the aluminum plate.
In Comparative Example 2, 304 3 / 4H having a thickness of 0.2 mm was used as the stainless steel plate, and aluminum A1050 having a thickness of 0.8 mm was used as the aluminum plate.
In Comparative Example 3, 304 3 / 4H having a thickness of 0.3 mm was used as the stainless steel plate, and aluminum A1050 having a thickness of 0.8 mm was used as the aluminum plate.

(Example 8)
SUS304 BA with a thickness of 0.25 mm was used as the stainless steel plate, and aluminum alloy A5052 with a thickness of 0.8 mm was used as the aluminum plate. Sputter etching was performed on SUS304 and A5052. Sputter etching for SUS304 was performed under conditions of 0.1 Pa, plasma output 4800 W, and line speed 4 m / min, and sputter etching for A5052 was performed under 0.1 Pa, plasma output 6400 W, line speed 4 m / min. It carried out on the conditions of a minute. SUS304 and A5052 after the sputter etching treatment were joined by roll pressure welding at room temperature at a rolling line load of 3.0 tf / cm to 6.0 tf / cm to obtain a rolled joined body of SUS304 and A5052. This rolled joined body was subjected to batch heat treatment at 300 ° C. for 8 hours.

(Examples 9 to 12)
In the same manner as in Example 8 except that the stainless steel plate type, tempering, thickness and / or the aluminum plate type of the original plate, the thickness was changed, and the pressing force at the time of joining was changed to a predetermined value. The rolled joined bodies of Examples 9 to 12 were obtained.
In Example 9, 304 1 / 2H having a thickness of 0.25 mm was used as the stainless steel plate, and aluminum alloy A5052 having a thickness of 0.8 mm was used as the aluminum plate.
In Example 10, 316L BA having a thickness of 0.2 mm was used as a stainless steel plate, and aluminum alloy A5052 having a thickness of 0.8 mm was used as an aluminum plate.
In Example 11, 304 BA having a thickness of 0.25 mm was used as a stainless steel plate, and aluminum A1050 having a thickness of 0.8 mm was used as an aluminum material.
In Example 12, 316L BA having a thickness of 0.25 mm was used as the stainless steel, and aluminum A1050 having a thickness of 0.8 mm was used as the aluminum plate.

(Example 7, Comparative Examples 4-6)
A rolled joined body (thickness: 0.403 to 1.025 mm) of a stainless steel plate and an aluminum alloy plate was prepared by a cold joining method. After the stainless steel plate and the aluminum alloy plate were subjected to brush polishing or the like, they were superposed, joined while cold rolling, and further heat treated.

Table 1 summarizes the type and thickness of each layer and the thickness ratio _PSUS of the stainless steel layer in the produced rolled joined body. In addition, using an X-ray diffractometer (Smartlab manufactured by Rigaku Corporation), X-ray diffraction measurement was performed on the stainless steel layer, and the peak half-value width FWHM ₂₀₀ indicating the crystal plane orientation (200) appearing at 2θ = 48 to 52 ° was obtained. It was measured. The measurement results are shown in Table 1. About the produced rolling joined body, the overhang height by an Eriksen test was measured. The measurement was performed according to JIS Z 2247 (Eriksen test method) using a mechanical Erichsen tester ESM-1 (CAP 2 mm, manufactured by Tokyo Henki Tester Co., Ltd.). Further, the surface hardness Hv of the stainless steel layer was measured in accordance with JIS Z 2244 (Vickers hardness test-test method) using a micro Vickers hardness meter (load 200 gf). Table 1 shows the measurement results of the overhang height and Vickers hardness. Further, the roll-bonding of Example 12 and Comparative Examples 1 to 6, Figure 2 shows the relationship between the half width _{FWHM 200} of a peak indicating a ratio _{P SUS} and the plane orientation of the thickness of the stainless steel layer (200) . Furthermore, Figure 3 shows the relationship between the thickness _{T SUS} and half width _{FWHM 200} of the stainless steel layer. Further, FIG. 4 shows the relationship between the stainless steel layer thickness ratio _PSUS and the surface hardness of the stainless steel layer. Note that the half width measurement was performed by polishing the sample. The polishing method is not particularly limited, but buffing or electrolytic polishing is preferable for the surface treatment during polishing. Care must be taken with polishing methods that are severely ground, as they can affect the FWHM ₂₀₀ .

As shown in Table 1 and FIG. 2, the following formula FWHM ₂₀₀ ≦ 0.0057P _SUS +0.4
All of the rolled joined bodies of Examples satisfying the above conditions showed a high value of an overhang height of more than 7 mm according to the Erichsen test, and it was revealed that the processability was excellent. On the other hand, the rolling joined bodies of Comparative Examples 1 to 6 that do not satisfy the conditions of the above formulas had an overhang height of less than 7 mm, which was insufficient as a rolled joined body for a casing. Moreover, as shown in Table 1 and FIG. 3, the following formula FWHM ₂₀₀ ≦ 0.571T _SUS +0.4
It has been clarified that the moldability is improved by satisfying the above conditions.

DESCRIPTION OF SYMBOLS 1 Rolled joined body 10 Stainless steel layer 20 Metal layer different from stainless steel 5 Electronic device casing 50 Back surface 51 Side surface A Flat portion

Claims (3)

A two-layer or three-layer rolled joined body comprising a stainless steel layer and a metal layer that is aluminum or an aluminum alloy ,
The thickness T is 0.4 mm or more and 3 mm or less,
The overhang height by the Eriksen test is 7.0 mm or more,
The ratio _{P SUS} thickness _{T SUS} of the stainless steel layer to said thickness T, the relationship between the half width _{FWHM 200} of the peak at lattice orientation (200) of the crystals obtained when the stainless steel layer side was measured X-ray diffraction However, the rolled joined body satisfies the following formula.
FWHM ₂₀₀ ≦ 0.0057P _SUS +0.4 The rolled joined body according to claim 1 for an electronic equipment casing. Electronics housing with roll assembly according to claim 1.

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