JP2005271015A - Friction welding method of steel tube and aluminum alloy hollow member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the friction welding method of a steel tube and an aluminum alloy hollow member, with which formation of inter-metallic compounds and oxides is suppressed, high joining strength can be obtained under a load of a low upset pressure, deformation of an aluminum alloy tube at the time of joining can be suppressed, and which is particularly suitable for friction welding between a carbon steel tube or an alloy steel tube of a diameter ≥50 mm and a thickness <5 mm and an aluminum alloy hollow member. <P>SOLUTION: This is a friction welding method between a carbon steel tube or an alloy steel tube of a diameter ≥50 mm and a thickness <5 mm and an aluminum alloy hollow member. The method consists of a friction process in which the two members A, B are made to butt at each other, and a relative rotary friction is performed under a frictional pressure (P1) 10-80 MPa until a friction upset length (U1) of 0.1-2.0 mm is achieved and an upsetting process in which an upset pressure (P2) is set at 60-130 MPa (provided P1≤P2). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a friction welding method between a steel pipe and an aluminum alloy hollow member. Specifically, a carbon steel pipe or an alloy steel pipe (excluding a stainless steel pipe) having a diameter of 50 mm or more and less than 5 mm in thickness, an aluminum alloy pipe, a hollow extruded material, a hollow The present invention relates to a method of friction welding a hollow aluminum alloy member made of a casting or the like.

  In joining steel and aluminum alloy materials, fusion welding such as MIG welding, TIG welding, and electron beam welding is difficult because a brittle intermetallic compound of iron and aluminum is formed during welding. Friction welding that does not form a liquid phase is sometimes attempted, but the friction welding between the two is not easy and the joint strength close to the strength of the aluminum alloy base material has not been obtained. Is only known as the only mass-produced product (ATZ Automobiltecnische Zeitschrift 99 (1997) 5, pages 256-263).

  Against this background, various techniques have been proposed in order to obtain an improved friction welding method between a steel material and an aluminum alloy material. For example, in order to obtain a joint strength close to that of an aluminum alloy base material, the Mg content of the aluminum alloy and the carbon content of the steel material are specified, and the actual friction time of the two members is regulated in relation to the carbon content. , A method of friction welding with an upset pressure as a specific range (see Patent Document 1), an aluminum tube and a steel tube are interposed between an aluminum material as a base material and a stainless steel fiber as a reinforcing material, and the aluminum tube and the steel tube are friction welded. A method for obtaining a joint (see Patent Document 2) has been proposed.

However, in these methods, a structure in which an automobile member made of a large steel hollow member having a diameter of 50 mm or more, such as an automobile propeller shaft, axle housing, or torsion bar, is partially replaced with an aluminum alloy hollow member. In order to realize the mass production method in which the steel pipe and the aluminum alloy hollow member are friction-welded to achieve this, it is not always satisfactory in terms of the mechanical capacity and manufacturing cost of the pressure welding machine.
Japanese Patent Laid-Open No. 5-138371 JP-A-5-185253

  As shown in FIGS. 1 and 2, the friction welding is performed by abutting two materials A and B to be joined together and achieving a set friction margin (U1) while applying the friction pressure (P1). A friction process in which rotation is relatively performed until the offset margin (U1 becomes 0), and an upset process in which the rotation is stopped by applying a brake to the rotation while applying the upset pressure (P2) after the completion of the friction process. It is. In the upset process, an upset margin (U2) is generated, and as a result of the total margin of the friction margin and the upset margin, and as a result of the total margin (U), burrs are generated, and intermetallic compounds and oxides formed at the joint interface. Is excluded as a burr. FIG. 1 is a view showing the occurrence of burrs in the friction process in a state where the materials A and B are abutted before friction welding, and FIG. 2 is a state after the friction process is finished.

  When a steel material and an aluminum alloy material, particularly an Al—Mg alloy material, are friction welded, intermetallic compounds such as an Al—Fe compound and oxides are likely to be formed, and bonding is hindered. Previously, it was considered necessary to increase the upset pressure P2 as much as possible in order to eliminate the intermetallic compounds and oxides at the interface, and to secure the metal bond. However, the steel material does not deform even when pressed at a high P2. Therefore, a congested region (dead metal zone) of an aluminum alloy is formed at the joining interface, and it is not easy to exclude intermetallic compounds and oxides as burrs. Also, pipes, particularly, a diameter of 50 mm or more and a wall thickness of less than 5 mm When the large-sized thin tubes are pressed against each other, even if P2 is less than the proof stress of the material, the vicinity of the interface of the aluminum alloy tube is deformed in the radial direction, and the burr flow of the aluminum alloy is It becomes difficult to obtain a good joint because it becomes uneven on the diameter side and shear force is generated at the interface.

  In order to eliminate the above-mentioned conventional problems in the friction welding of a steel pipe and an aluminum pipe, the inventors have developed the Mg content, friction pressure, friction in the friction process of the Mg-containing aluminum alloy in which a brittle Al—Fe compound is easily generated. As a result of diversified investigations on the relationship between friction welding conditions such as offset and upset pressure and bonding characteristics, it is possible to suppress the formation of intermetallic compounds and obtain improved bonding strength in a low P2 region. The pressure welding conditions were found.

  In addition, deformation of the aluminum alloy tube during friction welding occurs when the upset shift margin occurs after a friction process is completed, during a short period of time from when the upset pressure P2 is applied to when the rotation is braked and the rotation is stopped. Thus, it has been found that the deformation increases as the upset shift margin increases, and that the deformation when the upset shift margin occurs increases as the friction shift margin increases in the friction process.

  The present invention has been made as a result of further studies based on the above knowledge, and its purpose is to suppress the formation of intermetallic compounds and oxides, and to achieve high bonding strength with a low P2 load. It is also possible to suppress deformation of the aluminum alloy tube at the time of joining. In particular, the friction between the steel tube and the aluminum alloy hollow member suitable for friction welding of a carbon steel pipe or alloy steel tube having a diameter of 50 mm or more and a wall thickness of less than 5 mm and the aluminum alloy hollow member. It is to provide a pressure welding method.

  The friction welding method of the steel pipe and the aluminum alloy hollow member according to claim 1 for achieving the above object is a method of friction welding the carbon steel pipe or alloy steel pipe having a diameter of 50 mm or more and less than 5 mm in thickness and the aluminum alloy hollow member. Then, these two members are brought into contact with each other, and a friction process in which relative rotational friction is performed at a friction pressure (P1) of 10 to 80 MPa until a frictional margin (U1) of 0.1 to 2.0 mm is achieved, and an upset pressure ( It consists of an upset process which makes P2) 60-130 MPa (however, P1 <= P2).

  A friction welding method for a steel pipe and an aluminum alloy hollow member according to claim 2 is characterized in that, in claim 1, the aluminum alloy hollow member contains less than 2.0% Mg.

  The method of friction welding of a steel pipe and an aluminum alloy hollow member according to claim 3 is characterized in that, in claim 1, the aluminum alloy hollow member is an Al-Mg based alloy containing Mg as a main alloy component and containing Mg 2.0% or more, and The yield strength is adjusted to 150 MPa or more by work hardening, and P1 is 30 to 60 MPa, U1 is 0.1 to 1.5 mm, and P2 is 60 to 110 MPa (where P1 ≦ P2).

  The friction welding method of the steel pipe and the aluminum alloy hollow member according to claim 4 is the method according to claim 1, wherein P1 is set to 20 to 80 MPa, U1 is set to 0.1 to 1.5 mm, and U1 and the upset margin (U2) in the upset process The total shift margin (U) is controlled to 15 mm or less.

  The friction welding method for a steel pipe and an aluminum alloy hollow member according to claim 5 is characterized in that, in claim 4, the peripheral speed (V) of one member in the relative rotational friction is 0.8 to 3 m / s. To do.

  According to a sixth aspect of the present invention, there is provided a friction welding method for a steel pipe and an aluminum alloy hollow member according to the fourth aspect, wherein the rotary brake is applied after completion of the friction process, and when the pressure is switched from P1 to P2, the rotational brake is applied. P1 is switched to P2 after the elapse of time of at least 2 seconds and less than 0.4 seconds.

  According to the present invention, generation of intermetallic compounds and oxides is suppressed, high joint strength is obtained with a load of P2 in a low region, and deformation of the aluminum alloy tube at the time of joining can be suppressed. A friction welding method for a steel pipe and an aluminum alloy hollow member suitable for friction welding of a carbon steel pipe or alloy steel pipe having a thickness of less than 5 mm and an aluminum alloy hollow member is provided. The friction welding method is suitable for a structure in which a member that has conventionally been formed of a steel hollow member, for example, a member such as an automobile propeller shaft, axle housing, or torsion bar is partially replaced with an aluminum alloy. Can be applied.

  The present invention is a method of friction welding a carbon steel pipe or alloy steel pipe (excluding a stainless steel pipe) having a diameter of 50 mm or more and a wall thickness of less than 5 mm and an aluminum alloy hollow member, and is set by contacting these two members. .Friction process in which relative rotational friction is performed at a friction pressure (P1) of 10 to 80 MPa, and an upset pressure (P2) until a frictional margin (U1) of 1 to 2.0 mm is achieved (until U1 becomes 0). It consists of the upset process which makes 60-130 MPa (however, P1 <= P2).

  The end time of the friction process is controlled by the magnitude of the frictional margin (U1), and the applied friction pressure is preferably in the range of 10 to 80 MPa. If it is less than 10 MPa, it takes time to obtain the heating necessary for the metal bonding, and the aluminum alloy at the bonding interface is oxidized and the bonding strength decreases. If it exceeds 80 MPa, the interface becomes high temperature and intermetallic compounds are likely to be formed, and the upset pressure (P2) must be larger than P1 (P1 ≦ P2), so the applicable range of P2 is limited. Not practical. A more preferable lower limit value of P1 is 20 MPa, and a more preferable lower limit value is 30 MPa. A more preferable upper limit value of P1 is 60 MPa, and a more preferable upper limit value is 45 MPa.

  The friction margin (U1) is set to perform heating necessary to secure the metal bond, and the frictional pressure (P1) is applied until the set U1 becomes 0, so that the rotational friction is continued. The time of the friction process will be determined. The preferable range of U1 set in order to obtain the necessary heating at the interface is 0.1 to 2.0 mm. When excessive U1 exceeding 2.0 mm is set, an oxide layer is generated at the interface, The generated burrs cause a non-uniform metal flow when burring occurs immediately after upsetting. A more preferable range of U1 is 0.2 to 1.5 mm, and a more preferable range is 0.3 to 1.0 mm.

  The upset pressure (P2) finally determines the strength of the metal bond between the steel pipe and the aluminum alloy hollow member, and is preferably in the range of 60 to 130 MPa. If P2 is less than 60 MPa, the bonding strength is not sufficient, and if it exceeds 130 MPa, the total margin (U), which is the sum of the friction margin (U1) and the upset margin (U2), increases, and the inside of the aluminum alloy hollow member and In the case of an aluminum alloy tube on the outside, the non-uniformity of the flow of burrs generated on the inner diameter side and the outer diameter side increases, and as a result, a shearing force is generated at the interface and the bonding strength decreases. In particular, in the case of aluminum alloy pipes, as long as steel pipes and aluminum alloy pipes are industrial products, roundness, wall thickness, and material variations cannot be avoided. It is desirable that the upper limit of P2 be limited to 130 MPa because minute deformation occurs in the aluminum alloy tube and the flow of burrs becomes uneven. A more preferable range of P2 is 60 to 115 MPa, and a more preferable range is 60 to 110 MPa.

  Other mechanical factors in the friction welding work conditions include the rotational speed N, brake timing, and upset time T2, and the brake timing and upset time T2 are usually implemented in friction welding between steel or cast iron and between aluminum alloys. The applied range, for example, the brake timing is changed from P1 to P2 after 0 to 0.5 seconds have elapsed after the rotary brake is applied, and 2 to 30 seconds is applied as the upset time T2. As for the rotational speed N, a range of 800 to 3000 rpm is usually applied. In the present invention, in order to make U2 small and make the flow of burrs uniform, the upper limit is 1260 rpm (4.0 m / s), More preferably, it should be limited to 1200 rpm (3.8 m / s).

  A preferred embodiment of the present invention will be described. In the first embodiment, in addition to the above basic conditions, an aluminum alloy hollow member containing less than 2.0% Mg is used. By setting the Mg content to less than 2%, the generation of Fe—Al intermetallic compounds that are detrimental to bondability can be suppressed. In this case, a more preferable range of P1 is 20 to 60 MPa, a further preferable range is 20 to 45 MPa, and a more preferable range of U1 is 0.2 to 1.0 mm. A more preferable range of P2 is 60 to 115 MPa.

  In a second preferred embodiment, the aluminum alloy hollow member is an Al—Mg-based alloy containing Mg as a main alloy component, and contains 2.0% or more of Mg, and the yield strength is adjusted to 150 MPa or more by work hardening. , P1 is 30 to 60 MPa, U1 is 0.1 to 1.5 mm, and P2 is 60 to 110 MPa (where P1 ≦ P2).

  Mg dissolves in aluminum to increase the strength and improve workability and corrosion resistance. A preferable Mg content is in the range of 2% or more. When the strength is further increased by work hardening so that the proof stress is 150 MPa or more and an upset pressure is applied in the friction welding, the aluminum alloy tube is prevented from deforming in a trumpet shape in the radial direction in the vicinity of the joint. The upper limit of the amount of Mg is not particularly limited, but is preferably about 6.0% or less from the viewpoint of hot extrudability and hot rollability, and the upper limit of yield strength by work hardening is about 300 MPa.

  In the Al—Mg-based alloy containing Mg of 2.0% or more, in order to suppress the formation of brittle Al—Fe intermetallic compounds in the friction process of friction welding, P1 is set to 30. -60 MPa, more preferably 30-45 MPa, and U1 is 0.1-1.5 mm, more preferably 0.2-1.0 mm. It is necessary to set P2 to 60 to 110 MPa (where P1 ≦ P2). When P2 exceeds 110 MPa, even if P2 is less than the yield strength of the aluminum alloy tube, slight deformation of the aluminum alloy tube occurs during the upset process. The flow of burrs becomes uneven, especially in the case of an Al-Mg alloy, since the deformation resistance at high temperature is high, the pressure when the metal begins to flow as burrs is high and is likely to cause fine deformation. The deformation is increasingly increased.

  In the third preferred embodiment of the present invention, P1 is set to 20 to 80 MPa, U1 is set to 0.1 to 1.5 mm, P2 is set to 60 to 130 MPa, more preferably 60 to 115 MPa, and U1 and the upset offset in the upset process ( This is a mode in which the total margin (U) consisting of U2) is controlled to 15 mm or less.

  U is the sum of U1 set in the friction process and the upset shift margin (U2) inevitably generated by the upset pressure, but since the deformation of the aluminum alloy hollow member occurs when U2 occurs, U2 is preferably as small as possible. Since small burrs caused by U1 also induce deformation at the time of upsetting, it is preferable to reduce U (= U1 + U2). By setting U to 15 mm or less, deformation of the aluminum alloy hollow member and non-uniformity of the flow of burrs are reduced. It can suppress and can raise joint strength.

  In the third embodiment, the peripheral speed of a member that rotates during rotational friction greatly affects the heat generation speed and the magnitude of U2 in the friction process. It is more desirable that the peripheral speed (V) of one member in relative rotational friction is 0.8 to 3 m / s. When the peripheral speed (V) is less than 0.8 m / s, it takes time to obtain the heating necessary for metal bonding, and the heating area near the interface is expanded, and uneven deformation is likely to occur in the subsequent upset process. Become. U2 occurs in a very short time from the end of the friction process to when the rotary brake is applied until it stops, and during this time, the contacting members increase in proportion to the length at which the contacting parts slide against each other. In order to reduce U2, it is necessary to reduce V, and it is preferable to limit it to 3 m / s or less. In general, when V exceeds 3 m / s, U2 increases, U exceeds 15 mm, and the bonding strength decreases.

  In the third embodiment, when the rotation brake is applied after the friction process is completed and the pressure is switched from P1 to P2, the start time of the P2 load is set without applying the rotation brake and simultaneously switching from P1 to P2. The brake timing delay (P2L) to be delayed is set to 0.04 seconds or more and less than 0.4 seconds, and after applying the rotation brake, P1 is switched to P2 after the elapse of time of 0.04 seconds or more and less than 0.4 seconds. It is desirable to reduce U2 by reducing the time during which P2 is loaded. If P2L is less than 0.04 seconds, the effect is not sufficient. If 0.42 seconds or more, intermetallic compounds and oxides grow on the interface, and P2 is loaded only before the rotation stops. A sufficient metal bond cannot be obtained.

  Examples of the present invention will be described below in comparison with comparative examples to demonstrate the effects of the present invention. These examples are one embodiment of the present invention, and the present invention is not limited thereto.

  Steel pipe (STKM13A, outer diameter 60 mm, thickness 3 mm), Si: 0.61%, Fe: 0.11%, Cu: 0.27%, Mn: 0.02%, Mg: 1.07%, Cr : 0.06%, Ti: 0.03%, the ends of 6061 aluminum alloy pipe (tempered: T6, outer diameter 60 mm, thickness 3 mm) having a composition consisting of the balance Al and impurities are brought into contact with each other to produce a brake. Using a rotary friction welding machine, the steel pipe was rotated and friction welded. Table 1 shows the pressure contact conditions. After joining, the burr on the outer diameter side was removed and cut longitudinally to form a strip-shaped tensile test piece, and the joint portion was subjected to a tensile test. The test results are shown in Table 1. In Table 1, those outside the conditions of the present invention (Claim 1) are underlined.

  As shown in Table 1, the test material No. 1 according to claim 1 was used. 1-4 show the high tensile strength in which all exceed 190 MPa. On the other hand, test material No. No. 5 has a low P1, so that it takes time to obtain the heating necessary for metal bonding, and the aluminum alloy at the interface is oxidized, resulting in a low bonding strength. Test material No. No. 8 cannot obtain the high temperature required to secure the metal bond because U1 is small. No. 9 had a large U1 and thus overheated to produce an intermetallic compound, both of which had low bonding strength. Test material No. No. 6 has a low P2, so that the metal bond is not sufficient and the bonding strength is low. No. 7 has a high P2, so that the total margin (U) becomes large and the flow of burrs becomes non-uniform. As a result, a shearing force is generated at the interface and the bonding strength is reduced.

  As a representative example of the friction welding process according to the present invention, the test material No. 3 shows a process chart of friction welding of No. 3. As shown in FIG. 3, the aluminum alloy pipe is brought into contact with the steel pipe rotating at 1200 rpm to start friction (time 0.2 seconds), the friction pressure (P1) is kept at 40 MPa, and the friction margin (U1) is about When it reaches 1 mm, the friction process is terminated (time 0.68 seconds). Subsequently, the process proceeded to the upset process, the rotation was stopped by applying a rotation brake, the upset pressure (P2) was set to 80 MPa, this pressure was maintained for 8 seconds, and the friction welding was finished. It takes about 0.7 seconds from applying the rotary brake to stopping (stop time 1.45 seconds), and a large margin is generated during this time. In this figure, the actual friction time from the start of the friction until the rotation stops takes 1.25 seconds.

  A steel pipe (STKM15A, outer diameter 50 mm, thickness 2.4 mm) 6082 forged material (composition: Si 1.0%, Mn 0.75%, Mg 0.9) having a hollow portion whose end face is the same shape as the steel pipe. %, Cross section: FIG. 4) was friction welded. The conditions were P1: 25 MPa, P2: 110 MPa, U1: 0.5 mm, rotation speed (N): 1000 rpm, brake timing delay (P2L): 0.2 s, T2: 10 s. When the torsion test was performed after the pressure welding, the joint did not break even under a torque load of 5000 N · m, and the tensile strength was excellent at 252 MPa when the tensile test piece was taken from the joint and the tensile test was performed. The value was shown.

  The steel pipe (STKM13A, outer diameter 60 mm, thickness 3.1 mm) and the ends of the Al-Mg alloy pipe (outer diameter 60 mm, thickness 3.1 mm) shown in Table 2 with adjusted work hardening degree are brought into contact with each other. Using a brake type rotary friction welding machine, the steel pipe was rotated and friction welding was performed. The pressure contact conditions were: friction pressure (P1): 40 MPa, friction margin (U1): 0.5 mm, upset pressure (U2): 80 MPa, rotational speed (number of revolutions): 1000 rpm, brake timing delay (P2L): 0. 2 seconds, upset time: 8 seconds.

  After joining, the burr on the outer diameter side was removed and cut longitudinally to form a strip-shaped tensile test piece, and the joint portion was subjected to a tensile test. The results are shown in Table 2. As shown in Table 2, the test materials No. 1 and B were adjusted to 150 MPa or more by cold working. Nos. 10 to 13 have good bonding strength, but test materials No. 14-15, test material No. which is not cold-worked even if the proof stress is 150 MPa or more. No. 16 has inferior bonding strength. In Table 2, those outside the conditions of the present invention (Claim 3) are underlined.

  Steel pipe (STKM13A, outer diameter 60 mm, thickness 3.1 mm), Si: 0.05%, Fe: 0.16%, Cu: 0.04%, Mn: 0.05%, Mg: 3.6% , Cr: 0.21%, Ti: 0.03%, the ends of a 5154 aluminum alloy tube having a composition consisting of the balance Al and impurities (tempered: H32, outer diameter 60 mm, thickness 3.1 mm) are in contact with each other The steel pipe was rotated and friction welded using a brake type rotary friction welding machine. Table 3 shows the pressure contact conditions. After joining, the burr on the outer diameter side was removed and cut longitudinally to form a strip-shaped tensile test piece, and the joint portion was subjected to a tensile test. The test results are shown in Table 3. In Table 3, those outside the conditions of the present invention (Claim 3) are underlined.

  As shown in Table 3, the test material No. 17-22 all have high joint strength exceeding 130 MPa. In contrast, any one of P1, P2, and U1 is a test material No. 23-28 are inferior in joint strength.

  5052 cold-pressed material (composition: Mg2.5%, Cr0.23%, proof stress) with a steel pipe (STKM15A, outer diameter 80mm, thickness 2.4mm) as the rotation side and a hollow part whose end face is the same shape as the steel pipe 176 MPa, cross section: FIG. 5) was friction welded. The conditions were P1: 35 MPa, P2: 100 MPa, U1: 0.5 mm, rotation speed (N): 1000 rpm, brake timing delay (P2L): 0.2 s, T2: 8 s. When the torsion test was performed after the pressure welding, the joint did not break even under a torque load of 5000 N · m. When a tensile test piece was taken from the joint and a tensile test was performed, the tensile strength was as high as 142 MPa. The value is shown.

  Steel pipe (STKM13A, outer diameter 60.5 mm, thickness 3.1 mm), Si: 0.62%, Fe: 0.13%, Cu: 0.26%, Mn: 0.03%, Mg: 1. 0561, Cr: 0.06%, Ti: 0.03%, 6061 aluminum alloy tube having a composition consisting of the balance Al and impurities (tempered: T6, outer diameter 60.5 mm, thickness 3.1 mm), Si : 0.06%, Fe: 0.17%, Cu: 0.03%, Mn: 0.05%, Mg: 3.8%, Cr: 0.19%, Ti: 0.03%, balance Al And 5154 aluminum alloy tube having a composition comprising impurities (tempering: H34, outer diameter 60.5 mm, thickness 3.1 mm) and Si: 0.08%, Fe: 0.08%, Cu: 4.32% , Mn: 0.65%, Mg: 1.65%, Ti: 0.02%, balance Al The ends of 2124 aluminum alloy pipes (tempered: T6, outer diameter: 60.5 mm, thickness: 3.1 mm) having a composition composed of impurities and using a brake-type rotary friction welding machine, Rotating and friction welding. Table 4 shows the pressure contact conditions. After joining, the burr on the outer diameter side was removed and cut longitudinally to form a strip-shaped tensile test piece, and the joint portion was subjected to a tensile test. The test results are shown in Table 4. In Table 4, those outside the conditions of the present invention (Claims 4 to 6) are underlined.

  As shown in Table 4, the test material No. Nos. 29 to 39 have excellent bonding strength in combination with each aluminum alloy material. Test material No. Since No. 40 has a high peripheral speed, the total shift margin becomes large and the flow of burrs becomes non-uniform. As a result, a shearing force is generated at the interface and the bonding strength is reduced. Test material No. Since No. 41 had a large friction margin, it was overheated to produce an intermetallic compound, resulting in poor joint strength.

  6082 forging (composition: Si 1.1%, Mn 0.55%, Mg 0.90) having a steel pipe (STKM15A, outer diameter 50 mm, thickness 2.4 mm) as a rotation side and having a hollow portion whose end face is the same shape as the steel pipe %, Tempering: T6, cross section: Fig. 4). The conditions are P1: 25 MPa, P2: 110 MPa, U1: 0.5 mm, U: 12.6 mm, peripheral speed: 2.09 m / s (rotation speed (N): 800 rpm), brake timing delay (P2L): 0 .2s, T2: 10s. When the torsion test was performed after the pressure welding, the joint did not break even under a torque load of 5000 N · m. When a tensile test piece was taken from the joint and a tensile test was performed, the tensile strength was as high as 282 MPa. The value is shown.

In the friction welding of this invention, it is a partial cross section figure which shows the state which faced | matched two hollow members before pressure welding. FIG. 5 is a partial cross-sectional view showing a state in which burrs are formed by moving two hollow members toward each other by the frictional shift after the end of the friction process in the friction welding of the present invention. It is a figure which shows an example of the process chart of the friction welding of this invention. In this invention, it is a partial cross section figure which shows the friction welding state of a steel pipe and an aluminum alloy forging material. In this invention, it is sectional drawing which shows the friction welding state of a steel pipe and an aluminum alloy cold press material.

Claims (6)

A method of friction welding a carbon steel pipe or alloy steel pipe having a diameter of 50 mm or more and a wall thickness of less than 5 mm and an aluminum alloy hollow member, wherein these two members are abutted, and a frictional margin (U1) of 0.1 to 2.0 mm is obtained. A steel pipe comprising a friction process in which relative rotational friction is performed at a friction pressure (P1) of 10 to 80 MPa until an achievement is achieved, and an upset process in which the upset pressure (P2) is 60 to 130 MPa (where P1 ≦ P2). And friction welding method of aluminum alloy hollow member. 2. The method of friction welding of a steel pipe and an aluminum alloy hollow member according to claim 1, wherein the aluminum alloy hollow member contains less than 2.0% (mass%, hereinafter the same) Mg. The aluminum alloy hollow member is an Al—Mg-based alloy containing Mg as a main alloy component and contains 2.0% or more of Mg, and the proof stress is adjusted to 150 MPa or more by work hardening, and P1 is 30 to 60 MPa. The method of friction welding of a steel pipe and an aluminum alloy hollow member according to claim 1, wherein U1 is 0.1 to 1.5 mm and P2 is 60 to 110 MPa (where P1≤P2). 2. P1 is set to 20 to 80 MPa, U1 is set to 0.1 to 1.5 mm, and a total shift margin (U) including U1 and an upset shift margin (U2) in an upset process is controlled to 15 mm or less. The friction welding method of the steel pipe and aluminum alloy hollow member of description. The method of friction welding of a steel pipe and an aluminum alloy hollow member according to claim 4, wherein the peripheral speed (V) of one member in the relative rotational friction is 0.8 to 3 m / s. When the rotation brake is applied after the friction process is completed and the pressure is switched from P1 to P2, after the rotation brake is applied, P1 is switched to P2 after a lapse of 0.04 seconds or more and less than 0.4 seconds. A friction welding method for a steel pipe according to claim 4 and an aluminum alloy hollow member.

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