JP2019013969A - Welding joint of aluminum material and method for producing the same - Google Patents

Abstract

To provide a welding joint of aluminum alloy material having high strength and high joint efficiency, and a method of producing the same.SOLUTION: A welding joint of aluminum alloy material is a welding joint obtained by welding a plurality of aluminum alloy materials. The welded metal part has a composition comprising Mg: 4.0-10.0 mass%, Mn: 0.05-0.30 mass%, Cu: 0.10-1.00 mass%, Cr: 0.05-0.25 mass% and Zn: 0.10-0.50 mass%, with Fe: 0.4 mass% or less, Si: 0.4 mass% or less, Zr: 0.05 mass% or less and Ti: 0.25 mass% or less, with the balance being Al and inevitable impurities. There is also provided method for producing the same.SELECTED DRAWING: None

Description

  The present invention relates to a welded joined body of aluminum alloy material having high strength and excellent joint efficiency and a method for producing the same, and more particularly, to a welded joined body of aluminum alloy material suitably used for transportation equipment and semiconductor manufacturing equipment, and the method thereof. It relates to a manufacturing method.

  In recent years, aluminum alloys have been used in structures such as transportation equipment and semiconductor manufacturing equipment. In applying an aluminum alloy, it is necessary to satisfy the strength, corrosion resistance, formability, bondability and the like required for each part, and various studies have been made.

  As a conventionally used aluminum alloy material for high-strength welded joints, 5083 alloy is known. The 5083 alloy is an Al—Mg alloy containing 4.0 to 4.9 mass% of Mg, and the lower limit of strength in the JIS standard is 275 MPa.

  Arc welding, electron beam welding, laser welding, or the like is used as a welding method for producing a welded joint of an Al—Mg alloy. In addition, when a filler material is used for welding, the filler material is selected in accordance with the guidelines shown in JIS Z3604. That is, the filler materials selected when welding 5083 alloy are 5183, 5356, and 5556. By using these filler materials, weld cracking can be suppressed and high joint strength can be obtained.

  On the other hand, the demand for higher strength of the aluminum welded body is increasing year by year. By increasing the strength of the aluminum welded body, it is possible to reduce the required thickness of the constituent material at the same load capacity and further reduce the weight. Thus, cost reduction can be realized by reducing the material cost.

  The strength of the heat-affected zone and the weld metal zone produced when welding is greatly affected by the strength of the aluminum welded body. As described in JIS Z3001-1, the heat-affected zone is defined as a portion of an unmelted base material in which the structure, metallurgical properties, mechanical properties, etc. have changed due to the heat of welding. . Further, as described in JIS Z3001-1, the weld metal is also defined as a metal that has melted and solidified during welding at a part of the weld.

  That is, it is effective to increase the strength of the heat-affected zone and the weld metal zone that occur during welding to increase the strength of the welded body. The Al—Mg-based alloy constituting the present invention is known as a non-heat-treatable alloy, and the strength of the heat-affected zone produced during welding is equivalent to the O-material strength of the base material. Therefore, the strength of the welded body made of an Al—Mg alloy depends on the strength of the O metal of the aluminum alloy material constituting the welded body to be used and the strength of the weld metal part to be formed. In order to increase the strength of the Al—Mg-based alloy welded body, it is necessary to improve both the strength of the O material and the strength of the weld metal part.

  Patent Document 1 proposes an Al—Mg alloy to which Sc is added as a high-strength aluminum alloy for welding. However, the addition of expensive Sc has no industrial advantage, and Patent Document 1 does not evaluate the performance of a joint when using a filler metal. Thus, in patent document 1, when using a filler material, there existed a problem that the filler material etc. for obtaining the outstanding characteristic were unknown.

Japanese Patent Application Laid-Open No. 10-237577

  This invention is made | formed in view of the said problem, Comprising: It aims at providing the welding joined body of the aluminum alloy material which has high intensity | strength and high joint efficiency. Another object of the present invention is to provide a simple method for producing a welded assembly of the aluminum alloy material.

  That is, the present invention is the welded joint obtained by welding a plurality of aluminum alloy materials according to claim 1, wherein the composition of the weld metal part is Mg: 4.0 to 10.0 mass%, Mn: 0.05 to 0.00. 30 mass%, Cu: 0.10 to 1.00 mass%, Cr: 0.05 to 0.25 mass% and Zn: 0.10 to 0.50 mass%, Fe: 0.4 mass% or less, Si: 0 The welded joint of aluminum alloy material is characterized in that it is restricted to .4 mass% or less, Zr: 0.05 mass% or less and Ti: 0.25 mass% or less, and consists of the balance Al and inevitable impurities.

  According to a second aspect of the present invention, in the first aspect, the plurality of aluminum alloy base materials constituting the joined body are Mg: 4.0 to 10.0 mass%, Mn: 0.05 to 0.30 mass%, Cu: 0. 10 to 1.00 mass%, Cr: 0.05 to 0.25 mass% and Zn: 0.10 to 0.50 mass%, Fe: 0.4 mass% or less, Si: 0.4 mass% or less, Zr : 0.05 mass% or less and Ti: 0.25 mass% or less, and the balance is Al and inevitable impurities.

  According to a third aspect of the present invention, in the first or second aspect, the Vickers hardness Hw of the weld metal part is 70.0 Hv or more, the Vickers hardness Hh of the heat affected zone is 80.0 Hv or more, and Hw / Hh. Was 0.80 or more.

  According to the present invention, in claim 4, Mg: 4.0 to 10.0 mass%, Mn: 0.05 to 0.30 mass%, Cu: 0.10 to 1.000 mass%, Cr: 0.05 to 0.25 mass. And Zn: 0.10 to 0.50 mass%, Fe: 0.4 mass% or less, Si: 0.4 mass% or less, Zr: 0.05 mass% or less, and Ti: 0.25 mass% or less. In addition, a plurality of aluminum alloy materials composed of the balance Al and inevitable impurities are used, Mg: 4.0 to 10.0 mass%, Mn: 0.05 to 0.30 mass%, Cu: 0.10 to 1.000 mass% Cr: 0.05 to 0.25 mass% and Zn: 0.10 to 0.50 mass%, Fe: 0.4 mass% or less, Si: 0.4 mass% or less, Zr: 0 Welding and joining of aluminum alloy materials characterized by welding the plurality of aluminum alloy materials using a filler material consisting of the balance Al and inevitable impurities, regulated to 05 mass% or less and Ti: 0.25 mass% or less It was set as the manufacturing method of the body.

  According to the present invention, a welded joined body of aluminum alloy material having high strength and high joint efficiency can be obtained. Further, according to the present invention, such a welded joined body of aluminum alloy material can be easily manufactured.

  As a result of repeated sincerity studies, the present inventors obtain a welded joint of aluminum alloy material having high strength and high joint efficiency by adjusting the composition of the weld metal part in the welded joint of aluminum alloy material. As a result, the present invention has been completed.

  Below, the welded joined body of the aluminum alloy material which concerns on this invention is demonstrated in detail.

1. First, the alloy composition of the weld metal part in the welded joint of the aluminum alloy material according to the present invention will be described. When this alloy composition is roughly classified, Mg, Mn, Cu, Cr and Zn are used as essential elements, and Fe, Si, Zr and Ti are used as restricting elements. The aluminum alloy material welded joint according to the present invention achieves high strength and high joint efficiency by adjusting these alloy compositions.

1-1. Essential element Mg: 4.0-10.0 mass%
Mg is an element that improves the hardness of the weld metal part by forming a solid solution in the weld metal part. If the Mg content is less than 4.0 mass% (hereinafter simply abbreviated as “%”), the weld metal part has low hardness and a high strength welded joint cannot be obtained. On the other hand, if the Mg content exceeds 10.0%, stress corrosion cracking tends to occur. The Mg content is preferably 4.5 to 6.5%.

Mn: 0.05-0.30%
Mn is an element that improves the ductility of the welded joint by forming a solid solution in the weld metal part. If the Mn content is less than 0.05%, the workability of the welded joint is lowered. On the other hand, when the Mn content exceeds 0.30%, a coarse intermetallic compound is formed in the weld metal part, so that ductility is lowered and hardness of the weld metal part is lowered. The Mn content is preferably 0.05 to 0.20%.

Cu: 0.10 to 1.00%
Cu is an element that improves the hardness of the weld metal part by forming a solid solution in the metal contact part. If the Cu content is less than 0.10%, the weld metal part has low hardness, and a high-strength welded joint cannot be obtained. On the other hand, if the Cu content exceeds 1.00%, cracks are likely to occur in the weld metal part. The Cu content is preferably 0.10 to 0.65%.

Cr: 0.05-0.25%
Cr is an element that refines the crystal grains of the weld metal part and improves the stability of material properties. If the Cr content is less than 0.05%, a region having low hardness is formed in the weld metal portion, and the strength of the welded joint is lowered. On the other hand, when the Cr content exceeds 0.25%, an Al—Cr intermetallic compound is formed in the weld metal part, and the workability of the welded joint is lowered. The Cr content is preferably 0.05 to 0.15%.

Zn: 0.10 to 0.50%
Zn is an element that improves the ductility of the weld metal part. If the Zn content is less than 0.10%, the workability of the welded joint is lowered. On the other hand, if the Zn content exceeds 0.50%, stress corrosion cracking tends to occur. The Zn content is preferably 0.10 to 0.25%.

1-2. Regulating element Fe: 0.40% or less Fe exists as an Al—Fe-based intermetallic compound and an Al—Fe—Mn-based intermetallic compound in the weld metal part, and decreases the workability of the welded joint. Therefore, the Fe content is restricted to 0.40% or less. The lower the Fe content, the better. However, it is difficult to manage the Fe content at a very low value, and a high-purity raw material is required, leading to an increase in raw material cost. In the present invention, the lower limit of the Fe content is 0.05%.

Si: 0.40% or less Since Si is an element that forms a crack in the weld metal part, it is not preferable that Si be contained in the weld metal part. If the Si content exceeds 0.40%, cracking is likely to occur. Therefore, the Si content is restricted to 0.40% or less, preferably 0.25% or less. Managing the Si content at an extremely low value is difficult in production, and requires a high-purity raw material, leading to an increase in raw material cost. In the present invention, the lower limit value of the Si content is set to 0.05%.

Zr: 0.05% or less Zr is an element that exists as an Al—Zr-based intermetallic compound in the weld metal part and lowers the ductility of the weld metal part. Therefore, it is not preferable that Zr is contained. If the Zr content exceeds 0.05%, the workability of the welded joint is lowered. Therefore, the Zr content is regulated to 0.050% or less, preferably 0.02% or less. The lower limit of the Zr content is not particularly limited, but the productivity of the aluminum alloy material and filler material constituting the aluminum joined body may be lowered, so in the present invention it is 0.001%. To do.

Ti: 0.25% or less Ti is an element serving as a nucleus of crystal grain formation, and is an element having an effect of refining crystal grains in the weld metal portion. On the other hand, when there is too much Ti content, the workability of a welded joined body is reduced by being taken in a weld metal part as a coarse aggregate and oxide. Therefore, the Ti content is restricted to 0.25% or less, preferably 0.10% or less. Note that the lower limit of the Ti content is not particularly limited, but the productivity of the aluminum alloy material and filler material constituting the aluminum joined body may be lowered. To do.

1-3. Other Elements The weld metal part in the welded joint of the aluminum alloy material according to the present invention contains Al and unavoidable impurities as the balance in addition to the essential elements and the regulatory elements. Here, inevitable impurities include, for example, B, Bi, Ni and the like, and each is 0.050% or less, and if the total is 0.150% or less, the aluminum alloy material obtained in the present invention The characteristics as a welded joint are not impaired.

2. Alloy composition of aluminum alloy base material constituting welded joint body of aluminum alloy material In the welded joint body of aluminum alloy material according to the present invention, it is preferable that a plurality of aluminum alloy base materials constituting the aluminum alloy base material have a predetermined alloy composition. . When this alloy composition is roughly classified, Mg, Mn, Cu, Cr and Zn are used as essential elements, and Fe, Si, Zr and Ti are used as restricting elements. The aluminum alloy material welded joint according to the present invention achieves high strength and high joint efficiency by adjusting these alloy compositions.

2-1. Essential element Mg: 4.0 to 10.0%
Mg is an element that improves the hardness of the base material and the heat-affected zone by dissolving in an aluminum alloy. If the Mg content is less than 4.0%, the hardness of the heat-affected zone decreases, and a high-strength welded body cannot be obtained. On the other hand, if the Mg content exceeds 10.0%, cracks occur during hot working of the material. The Mg content is preferably 4.5 to 6.5%.

Mn: 0.05-0.30%
Mn is an element that improves the ductility of the base material and the heat-affected zone by solid solution and precipitation in the aluminum alloy. If the Mn content is less than 0.05%, the workability of the base material and the heat-affected zone decreases. On the other hand, when the Mn content exceeds 0.30%, the Al—Fe—Mn intermetallic compound is coarsened and the workability is lowered. The Mn content is preferably 0.05 to 0.20%.

Cu: 0.10 to 1.00%
Cu is an element that improves the hardness of the base material and the heat-affected zone by dissolving in an aluminum alloy. If the Cu content is less than 0.10%, the hardness of the heat-affected zone decreases, and a high-strength welded joint cannot be obtained. On the other hand, if the Cu content exceeds 1.00%, cracks are likely to occur during hot working. The Cu content is preferably 0.20 to 0.60%.

Cr: 0.05-0.25%
Cr is an element that refines crystal grains in an aluminum alloy and improves the stability of material properties. If the Cr content is less than 0.05%, regions having low hardness are formed in the base material and the heat-affected zone, and the strength of the welded joint is lowered. On the other hand, when the Cr content exceeds 0.25%, an Al—Cr-based intermetallic compound is formed in the aluminum alloy, and the workability decreases. The Cr content is preferably 0.05 to 0.15%.

Zn: 0.10 to 0.50%
Zn is an element that improves the ductility of the aluminum alloy. If the Zn content is less than 0.10%, the workability of the aluminum alloy material decreases. On the other hand, if the Zn content exceeds 0.50%, stress corrosion cracking tends to occur. The Zn content is preferably 0.10 to 0.25%.

2-2. Regulating element Fe: 0.40% or less Fe exists as an Al—Fe-based intermetallic compound and an Al—Fe—Mn-based intermetallic compound in an aluminum alloy, and lowers the workability of the aluminum alloy material. Therefore, the Fe content is restricted to 0.40% or less. The lower the Fe content, the better. However, it is difficult to manage the Fe content at a very low value, and a high-purity raw material is required, leading to an increase in raw material cost. In the present invention, the lower limit of the Fe content is 0.05%.

Si: 0.40% or less Since Si is an element that forms a crack in the heat-affected zone during welding, it is not preferable that Si is contained. If the Si content exceeds 0.40%, cracks occur in the heat-affected zone due to the heat effect during welding. Therefore, the Si content is restricted to 0.40% or less, preferably 0.25% or less. Managing the Si content at an extremely low value is difficult in production, and requires a high-purity raw material, leading to an increase in raw material cost. In the present invention, the lower limit value of the Si content is set to 0.05%.

Zr: 0.05% or less Zr is an element that exists as an Al—Zr-based intermetallic compound in an aluminum alloy and lowers the workability of the aluminum alloy material. Therefore, it is not preferable that Zr is contained. If the Zr content exceeds 0.05%, the workability of the aluminum alloy material decreases. Therefore, the Zr content is regulated to 0.05% or less, preferably 0.02% or less. In addition, although the lower limit of Zr content is not specifically limited, Since productivity of an aluminum alloy material may fall, it is set to 0.001% in this invention.

Ti: 0.25% or less Ti is an element serving as a nucleus of crystal grain formation and is an element having an effect of refining crystal grains of an aluminum alloy. On the other hand, when there is too much Ti content, workability falls by being taken in into an aluminum alloy as a coarse aggregate and an oxide. Therefore, the Ti content is restricted to 0.25% or less, preferably 0.10% or less. In addition, although the lower limit of Ti content is not specifically limited, Since productivity of an aluminum alloy material may fall, it is set to 0.001% in this invention.

2-3. Other Elements The aluminum alloy base material constituting the welded joint of the aluminum alloy material according to the present invention contains Al and unavoidable impurities as the balance in addition to the essential elements and the regulatory elements. Here, the inevitable impurities include, for example, B, Bi, Ni, etc., and if each is 0.050% or less and the total is 0.150% or less, the aluminum weld joint obtained in the present invention is used. There is no loss of physical properties.

3. Hardness of weld metal part and heat-affected zone in welded joint of aluminum alloy material In the welded joint of aluminum alloy material according to the present invention, there are three regions: weld metal part, heat-affected part, and base metal part. To do. The Al—Mg alloy is a non-heat-treatable alloy, and the strength of the heat-affected portion, that is, the weld metal portion and the heat-affected portion is equivalent to the tempered O showing the lowest strength in the aluminum alloy material Are known. Accordingly, the region having the lowest strength in the three regions having the same composition is the weld metal portion or the heat affected zone. Moreover, in the weld metal part where Mg concentration exceeds 4.0%, even if it is the same composition, intensity | strength falls compared with a heat affected zone, and the problem that the intensity | strength of a welded joint body falls arises. In order to suppress such a decrease in the strength of the aluminum welded joint, it is effective to improve the strength of the weld metal part to a level close to the heat-affected part.

  One guideline indicating the strength of the weld metal part and the strength of the heat-affected zone is the hardness obtained by the Vickers hardness test. This is a value obtained by pressing an indenter made of diamond with a specified load and measuring the size of the indentation formed. In the welded joint of the aluminum alloy material according to the present invention, the Vickers hardness of the weld metal part and the heat-affected zone was used as a strength indicator. That is, the Vickers hardness of the weld metal part is Hw, the Vickers hardness of the heat affected zone is Hh, Hw is 70.0 Hv or more, Hh is 80.0 Hv or more, and Hw / Hh is 0.80 or more. Is preferred. It is more preferable that Hw is 75.0 Hv or higher, Hh is 85.0 Hv or higher, and Hw / Hh is 0.82 or higher. If Hw is less than 70.0 Hv or Hh is less than 80.0, sufficient strength as a welded joint cannot be obtained. Moreover, if Hw / Hh is less than 0.80, the strength of the weld metal part is too low as compared with the heat-affected zone, and sufficient strength as a welded joint cannot be obtained. The upper limit values of Hw, Hh, and Hw / Hh are not particularly limited, but are determined by the composition and manufacturing method of the aluminum alloy material to be used and the welding method. Are about 115.0 Hv, 125.0 Hv, and 1.00, respectively.

4). Method for manufacturing welded joint of aluminum alloy material The welded joint of an aluminum alloy material according to the present invention uses a plurality of aluminum alloy materials having a predetermined alloy composition and a filler material, and performs arc welding, laser welding, electron beam It is manufactured by appropriately selecting and using a fusion welding method such as welding. These will be described in detail below.

4-1. Aluminum alloy material used for manufacturing welded joint of aluminum alloy material In the method for manufacturing an aluminum welded joint according to the present invention, Mg: 4.0 to 10.0%, Mn: 0.05 to 0.30%, Cu: 0.1 to 1.0%, Fe: 0.4% or less, Si: 0.4% or less, Cr: 0.05 to 0.25%, Zn: 0.10 to 0.50%, Zr : 0.05% or less, Ti: 0.25% or less, a plurality of aluminum alloy materials having a composition consisting of the balance Al and unavoidable impurities are used as materials.

  The weld metal part in the welded joint of the aluminum alloy material according to the present invention is formed by melting and solidifying a part of the aluminum alloy material during welding. And in order to manufacture the welded joint which is excellent in joint strength and joint efficiency, it is necessary to control the alloy composition of a weld metal part. Thus, in order to control the alloy composition of a weld metal part, it is necessary to manufacture a welded joint using an aluminum alloy material having a predetermined alloy composition.

  The alloy composition of the plurality of aluminum alloy materials used in the manufacture of the aluminum alloy material welded joint according to the present invention is the same as the alloy composition of the aluminum alloy base material constituting the welded joint described above. The reason for specifying the range is the same. Each of the plurality of aluminum alloys may have the same alloy composition, each of the plurality of aluminum alloys may have a different alloy composition, or the plurality of aluminum alloys may have several different alloy compositions. You may be divided into groups.

4-2, Filler used for manufacture of welded joint of aluminum alloy material In manufacture of welded joint of aluminum alloy, filler material may be used for the purpose of suppressing weld cracking and reducing heat input. is there. When using a filler metal, the weld metal part is formed by mixing and solidifying the aluminum alloy material and the filler material to be used.

  Even when an aluminum filler metal is used, in order to produce a welded joint having excellent joint strength and joint efficiency, it is necessary to control the composition of the weld metal part as described above. For this purpose, it is preferable to use an aluminum alloy filler material having a predetermined alloy composition as well as an aluminum alloy filler material having a predetermined alloy composition.

  In the method for producing an aluminum welded joint according to the present invention, Mg: 4.0 to 10.0%, Mn: 0.05 to 0.30%, Cu: 0.00. 1 to 1.0%, Fe: 0.4% or less, Si: 0.4% or less, Cr: 0.05 to 0.25%, Zn: 0.10 to 0.50%, Zr: 0.05 It is preferable that the plurality of aluminum alloy materials be welded with a filler material having an alloy composition consisting of% or less, Ti: 0.25% or less, the balance Al and inevitable impurities.

  By using the filler material having such an alloy composition, the weld metal portion formed by mixing and solidifying the filler material and the aluminum alloy material can have the above-described alloy composition.

4-3, Welding Method It is preferable to use a fusion welding method such as arc welding, laser welding, electron beam welding, or the like for the method of manufacturing an aluminum alloy welded joint according to the present invention. Below, each welding method is demonstrated in detail.

  When applying arc welding, TIG welding or MIG welding is appropriately selected. The thickness of the material to be welded is about 1 to 200 mm, and multi-pass welding of two or more passes is applied when the thickness exceeds 5 mm. The welding conditions are appropriately adjusted within a range of a welding current of 100 to 500 A, a welding voltage of 10 to 50 V, and a welding speed of 20 to 120 cm / min. As the shielding gas, argon, helium, or a mixed gas of argon and helium is used at a flow rate of 10 to 120 L / min. In addition, in high current MIG welding using a high current power source, the welding current is appropriately adjusted in the range of 400 to 1000 A, the shielding gas is doubled, a mixed gas of argon and helium inside, argon outside, Each is used at a flow rate of 10 to 120 L / min. At the time of arc welding, one or more filler materials are appropriately used. The diameter of the filler metal is 0.8 to 6.0 mm, and is appropriately selected depending on the welding machine used, the plate thickness of the material to be welded, and the like.

When laser welding is applied, a solid laser such as a fiber laser, a disk laser, or a YAG laser, a CO ₂ laser, or the like is used. The plate | board thickness of a to-be-welded material is about 0.2-20 mm. When the filler material is not used, the end surfaces of the materials to be welded are butted together and the butted portion is irradiated with laser. When using a filler material, a method of welding while feeding the filler material using a feeder, or a method of temporarily fixing a wire or a plate of the filler material component to the welded portion in advance is applied. . In addition, when welding using a filler material, you may provide the groove | channel for maintaining the surplus height formed with a filler material in a to-be-welded material. The laser output is appropriately adjusted in the range of 500 to 30000 W, the spot diameter is 0.05 to 1.0 mm in diameter, and the welding speed is 100 to 5000 cm / min. As the shielding gas, an inert gas such as nitrogen, argon or helium is used at a flow rate of 10 to 50 L / min. The diameter of the filler material used at the time of laser welding is 0.8 to 2.4 mm, and is appropriately selected depending on the welding machine used, the plate thickness of the material to be welded, and the like.

When electron beam welding is applied, the thickness of the material to be welded is about 1 to 250 mm, and welding is often performed in one or two passes. When the filler material is not used, the end surfaces of the materials to be welded are butted together and the butted portion is irradiated with an electron beam. When using a filler material, a method of welding while feeding the filler material using a feeder, or a method of temporarily fixing a wire or a plate of the filler material component to the welded portion in advance is applied. . In addition, when welding using a filler material, you may provide the groove | channel for maintaining the surplus height formed with a filler material in a to-be-welded material. The conditions for electron beam welding are appropriately adjusted within a range of a welding output of 1 to 60 kW and a welding speed of 10 to 200 cm / min. Welding is carried out in vacuum of ¹⁰ -4 ^{to 10} 0 Pa vacuum chamber. The diameter of the filler material used for electron beam welding is 0.8 to 6.0 mm, and is appropriately selected depending on the welding machine used, the thickness of the material to be welded, and the like.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

  First, an aluminum alloy having the alloy composition shown in Tables 1 and 2 was melt-cast by a conventional semi-continuous casting method (DC casting) to produce an ingot. Next, after performing a homogenization treatment at a homogenization temperature of 500 ° C. and a holding time of 1 hour, hot rolling is performed so that the hot rolling start temperature is 480 ° C. and the end temperature is 320 ° C. A hot-rolled sheet having a thickness of 3 mm was obtained. Thereafter, a part of the hot-rolled sheets was subjected to a cold rolling process to obtain a cold-rolled sheet having a thickness of 1 mm. The hot-rolled sheet and the cold-rolled sheet thus obtained were subjected to final annealing under the conditions of an annealing temperature of 350 ° C. and a holding time of 2 hours, and used as samples for evaluating welded joints. Alloy NO. 47, 48, 53, and 54 were not evaluated because cracks occurred during hot rolling.

About the said sample, the bending workability of the base material was evaluated by the bending test. Detailed evaluation conditions are as follows.
<1. Base material bending workability test>
A bending test was performed by a method based on JIS Z 2248. A No. 3 test piece was taken from a sample with a plate thickness of 1 mm and bent 180 °. By observing the test piece after the test with the naked eye, “X” indicates that a crack of 3 mm or more has occurred, “△” indicates that a crack of less than 3 mm has occurred, and “○” indicates that no crack has occurred. As evaluated.

  Moreover, in order to manufacture the electrode wire used at the time of MIG welding, a part of ingot of the alloy composition of Table 1 was cut out, and it was set as the billet for extrusion. The billet was preheated at a homogenization temperature of 490 ° C. and a holding time of 6 hours, and then formed into a rod shape of φ10 mm by extrusion. Thereafter, wire drawing and intermediate annealing were repeated to obtain an electrode wire of φ1.6 mm. The temperature of the intermediate annealing was 370 ° C., and the holding time was 4 hours. In this way, an electrode wire for MIG welding was produced.

  In producing the welded joint, MIG welding, laser welding, and electron beam welding were used. MIG welding and electron beam welding were applied to a sample with a plate thickness of 3 mm, and laser welding was applied to a sample with a plate thickness of 1 mm. Details are shown below.

<Method for producing a welded joint with a thickness of 3 mm by MIG welding>
After processing the end surfaces of two samples each having a thickness of 3 mm with a milling cutter, MIG welding was performed by I-shaped groove butt contact. The root gap during welding was 0 mm. A MIG welder was used for welding, and a φ1.6 mm wire made of an aluminum alloy shown in Table 1 was used as an electrode wire. MIG welding was performed with a welding current of 150 A, a welding speed of 50 cm / min, and one pass to produce a welded joint for evaluation. The same alloy composition was used for the two samples.

<Method of producing a welded joint with a thickness of 3 mm by electron beam welding>
The end faces of two samples having a thickness of 3 mm were made flat by milling to obtain a sample for electron beam welding. The groove shape at the time of welding was an I groove, and an electron beam was irradiated to the center of the butt portion to produce a joint by one-pass through welding. The welding conditions were an acceleration voltage of 40 kV, an output of 3 kW, and a welding speed of 3 m / min. In addition, no filler metal is used during welding. Welded joints were prepared with the same and different combinations of the alloy compositions of the two samples.

<Method for producing welded joint with plate thickness of 1 mm by laser welding>
The end surfaces of two samples having a plate thickness of 1 mm were flattened with a milling cutter and used as laser welding samples. The groove shape at the time of welding was an I groove, a laser was irradiated to the center of the butt portion, and a joint was produced by one-pass through welding. The welding conditions were an output of 2 kW and a welding speed of 15 m / min. In addition, no filler metal is used during welding. Welded joints were prepared with the same and different combinations of the alloy compositions of the two samples.

  The weld joint produced as described above was subjected to an analysis result of alloy composition in the weld metal part, hardness measurement, weld crack test, bending workability test, and stress corrosion crack test. Details of evaluation by each test are shown below.

<2. Analysis of alloy composition in weld metal>
The weld bead was cut from the weld joint in a direction perpendicular to the welding direction and polished to a mirror finish. Then, after grasping | ascertaining the weld metal part area | region from the composition image of SEM, the composition was analyzed by the point analysis by EPMA. In the analysis, quantification was performed by comparing with the analysis result of the standard sample of each element. For the measurement, a beam having a spot diameter of 100 μm was used, the entire weld metal part was analyzed at intervals of 200 μm in the thickness direction and the width direction, and the arithmetic average value thereof was taken as the composition of the weld metal part. The elements to be analyzed were Al, Mg, Mn, Cu, Fe, Si, Cr, Zn, Zr, and Ti.

<3. Hardness measurement>
The Vickers hardness of the heat-affected zone and the weld metal zone in the welded joint was measured by a method based on JIS Z 2244. After cutting in a direction perpendicular to the welding direction and finishing to a flat surface by polishing, the hardness was measured. For the measurement, the central part of the plate thickness was used. The measurement of the heat affected zone was in the range of 2 mm from the weld boundary. The arithmetic average value obtained by measuring 5 points each was taken as the hardness of the heat-affected zone and the weld metal zone. Further, Hw / Hh was also calculated, where the hardness of the heat affected zone was Hh and the hardness of the weld metal portion was Hw. Hw of 75.0 Hv or more was designated as “◎”, 70.0 Hv or more and less than 75.0 Hv as “◯”, and less than 70.0 Hv as “x”. In addition, Hh was 85.0 Hv or more as “◯” and less than 80.0 Hv as “Δ”. Furthermore, Hw / Hh was set to 0.80 or more “◯” and less than 0.80 to “Δ”.

<4. Weld cracks>
From the observation of the appearance and cross section of the welded joint of the welded joint, cracks in the weld metal part and the heat affected zone were evaluated. In the appearance observation of the welded portion, the presence or absence of cracks was evaluated with the naked eye after removing smut and the like adhering during welding with a wire brush. Moreover, in the cross-sectional observation of the welded portion, a cross section perpendicular to the welding direction was cut out, mirror-polished, and then evaluated for the presence or absence of cracks with an optical microscope. According to the above observations, “◎” indicates that no crack was observed in the appearance and the cross section of the weld, and “◯” indicates that crack was observed only in the cross section of the weld. What was evaluated was evaluated as "x".

<5. Bending workability>
The bending workability of the test piece collected from the welded joint was evaluated by a method according to JIS Z 3122. A test of front bending and back bending was performed on the test piece in which the welded portion was the center. The welded joint after the test was observed with the naked eye, and “×” indicates that a crack of 3 mm or more occurred, “◯” indicates that a crack less than 3 mm occurred, and “◎” indicates that no crack occurred on the sample surface. As evaluated.

<6. Stress corrosion cracking>
The stress corrosion cracking test was carried out by applying a load stress by three-point bending to one surface of a No. 2A specimen taken from a welded joint in accordance with JIS H8711 and placing it in a salt spray tank. The load stress was set to 70% of the 0.2% proof stress obtained in the proof stress base material tensile test. The test was carried out for 50 days, and the case where cracks did not occur was evaluated as ◎, the case where cracks occurred after 30 days, and the case where cracks occurred within 30 days as ×.

  The results of the above evaluations (1-6) are shown in Tables 3-11. Tables 3 to 5 are cases of welded joints by MIG welding, Tables 6 to 8 are cases of welded joints by electron beam welding, and Tables 9 to 11 are cases of welded joints by laser welding. .

  In Invention Examples 1 to 150, weld joints excellent in each evaluation were obtained in weld joints in which the alloy composition of the weld metal part was within the scope of the present invention.

  On the other hand, in Comparative Examples 1, 2, 19, 20, 33, and 34, the Mg content of the base material and the weld metal part used was less than 4.0%, so Hw and Hh were lowered.

  In Comparative Examples 3, 21, and 35, since the Mn content of the weld metal part was less than 0.05%, the bending workability of the welded joint was lowered.

  In Comparative Examples 4, 22, and 36, since the Mn content in the weld metal part exceeded 0.30%, Hw / Hh was lowered to less than 0.8, and the bending workability of the welded joint was lowered.

  In Comparative Examples 5, 23, and 37, since the Cu content of the base material and the weld metal part used was less than 0.10%, the hardness of Vickers of Hw and Hh was lowered. In Comparative Examples 6, 24, and 38, since the Cu content was less than 0.10%, Hw and Hw / Hh decreased.

  In Comparative Examples 7, 25, and 39, since the Fe content in the weld metal part exceeded 0.4%, the bending workability of the welded joint decreased.

  In Comparative Examples 8, 26, and 40, since the Si content of the weld metal part exceeded 0.4%, cracks occurred in the weld part, and bending workability also deteriorated.

  In Comparative Examples 9, 27, and 41, the Cr content of the weld metal part was less than 0.05%, so Hw was lowered.

  In Comparative Examples 10, 28, and 42, since the Cr content of the weld metal part exceeded 0.25%, the bending workability of the welded joint decreased.

  In Comparative Examples 11, 29, and 43, the Zn content in the weld metal part was less than 0.10%, so that the bending workability of the welded joint was lowered.

  In Comparative Examples 12, 30, and 44, stress corrosion cracking occurred because the Zn content in the weld metal part exceeded 0.50%.

  In Comparative Examples 13, 31, and 45, since the Zr content of the weld metal part exceeded 0.05%, the bending workability of the welded joint was lowered.

  In Comparative Examples 14, 32, and 46, since the Ti content of the weld metal part exceeded 0.25%, the bending workability of the welded joint decreased.

  In Comparative Examples 15 and 16, stress corrosion cracking occurred because the Mg content of the weld metal part exceeded 10.0%.

  In Comparative Examples 17 and 18, since the Cu content in the weld metal part exceeded 1.00%, the weld part was cracked, the bending workability was lowered, and stress corrosion cracking was also generated.

  According to the present invention, an aluminum welded joint having high strength and high joint efficiency, and a simple manufacturing method thereof can be obtained.

Claims (4)

  A welded joint obtained by welding a plurality of aluminum alloy materials, wherein the composition of the weld metal part is Mg: 4.0 to 10.0 mass%, Mn: 0.05 to 0.30 mass%, Cu: 0.10 to 1 0.00 mass%, Cr: 0.05 to 0.25 mass%, and Zn: 0.10 to 0.50 mass%, Fe: 0.4 mass% or less, Si: 0.4 mass% or less, Zr: 0.05 mass %, And Ti: 0.25 mass% or less, and consisting of the balance Al and unavoidable impurities, and a welded joint of aluminum alloy material.   A plurality of aluminum alloy base materials constituting the joined body are Mg: 4.0 to 10.0 mass%, Mn: 0.05 to 0.30 mass%, Cu: 0.10 to 1.000 mass%, Cr: 0.00. 0.5 to 0.25 mass% and Zn: 0.10 to 0.50 mass%, Fe: 0.4 mass% or less, Si: 0.4 mass% or less, Zr: 0.05 mass% or less, and Ti: 0.25 mass The welded joint of aluminum alloy material according to claim 1, wherein the welded joint is made of the balance Al and inevitable impurities.   The Vickers hardness Hw of the weld metal part is 70.0 Hv or more, the Vickers hardness Hh of the heat-affected zone is 80.0 Hv or more, and Hw / Hh is 0.80 or more. A welded joint of the aluminum alloy material described. Mg: 4.0 to 10.0 mass%, Mn: 0.05 to 0.30 mass%, Cu: 0.10 to 1.000 mass%, Cr: 0.05 to 0.25 mass%, and Zn: 0.10 Containing 0.50 mass%, Fe: 0.4 mass% or less, Si: 0.4 mass% or less, Zr: 0.05 mass% or less, and Ti: 0.25 mass% or less, and the remainder from Al and inevitable impurities Using multiple aluminum alloy materials
Mg: 4.0 to 10.0 mass%, Mn: 0.05 to 0.30 mass%, Cu: 0.10 to 1.000 mass%, Cr: 0.05 to 0.25 mass%, and Zn: 0.10 Containing 0.50 mass%, Fe: 0.4 mass% or less, Si: 0.4 mass% or less, Zr: 0.05 mass% or less, and Ti: 0.25 mass% or less, and the remainder from Al and inevitable impurities A method for producing a welded joined body of aluminum alloy materials, comprising welding the plurality of aluminum alloy materials using a filler material.