JPH079170A - Friction press welding method for aluminum alloy composite material - Google Patents

Abstract

PURPOSE:To enable the outflow of the ceramic particles or whiskers disintegrated more finely than the base metal parts to be integrated on joint surfaces to the outside in a softened state and the outflow of the softened part subjected to the influence of the friction heat near the joint surfaces to the outside in a softened state. CONSTITUTION:Friction press welding is executed while not only a total offset allowance but a friction offset allowance as well are measured. More specifically, the rotating speed of a round bar 11 is lowered when the friction offset allowance attains 3.5 to 7mm and the friction press welding is ended when the total offset allowance attains 10 to 20mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction welding method for aluminum alloy composite materials.

[0002]

2. Description of the Related Art Conventionally, as a friction welding method for this kind of aluminum alloy composite material, a method shown in "Friction welding of alumina particle dispersion type 6061 aluminum alloy composite material" of the Japan Institute of Light Metals in 1991 is known. This is because one of them is aluminum alloy and alumina particles 1
This is a friction welding method for two round bars made of an aluminum alloy composite material in which 6.1 vol% is dispersed and composited.

Specifically, while one round bar (hereinafter referred to as the first round bar) is fixed, the other round bar (hereinafter referred to as the second round bar) is rotated at a constant speed with the longitudinal direction as an axis. (Rotation speed 5
8 s ⁻¹ ) at a predetermined pressure P1 (hereinafter referred to as friction pressure) for a predetermined time t1 (hereinafter referred to as friction time)
The joint surface (that is, the end surface) of the second round bar is pressed toward the joint surface (that is, the end surface) of the first round bar to soften both joint surfaces by the frictional heat generated between both joint surfaces, and then the second joint The pressure P2, which is greater than the friction pressure P1, immediately after the rotation speed of the round bar is reduced and the second round bar is decelerated or immediately after the rotation of the second round bar is stopped.
(Hereinafter referred to as upset pressure) for a predetermined time t2
(Hereinafter referred to as upset time. However, it is performed at t2 = 5s.) The joining surface of the second round bar is pressed toward the joining surface of the first round bar to solidify and join the two joining surfaces in the softened state. There is.

Here, each pressure contact condition, that is, friction pressure P1 = 2
0, 30, 40, 50 MPa, upset pressure P2 = 6
0,80,100MPa, friction time t1 = 2,3,4,5
As a result of performing the pressure welding by combining s, the total deviation (that is, the difference between the length of the round bar before the pressure welding and the length of the round bar after the pressure welding) is determined by the friction time t1 regardless of the friction pressure P1 or the upset pressure P2. It increases with an increase in length, and increases with increasing frictional pressure P1 or upset pressure P2 at the same frictional time t1. Also, friction pressure P1 = 50 MPa, upset pressure P2
= 100 MPa and friction time t1 = 5 s, the total margin was the highest value (23.6 mm).

[0005]

Here, the friction pressure P1
= 30MPa, upset pressure P2 = 60MPa, and friction time t1 = 3s, the second round bar (or the first round bar after pressure welding)
FIG. 6 shows a structural diagram of the joint surface of the round bar) and the base metal portion, and FIG. 7 shows the hardness distribution in the vicinity of the joint surface of the second round bar (or the first round bar) after pressure welding in the same case.

As shown in FIG. 6, alumina particles 31 crushed finer than the base material and altered by heat are accumulated on the joint surface of the second member. Therefore, the difference in the volume ratio (vol%) of the alumina particles 31 between the joint surface and the base material portion becomes large, and the difference in tensile strength and rigidity between the joint surface and the base material portion becomes large. In addition, 30 shows an aluminum alloy.

Further, as shown in FIG. 7, a rapid change in hardness is recognized in the vicinity of the joint surface, and the hardness is about 2 to 5 from the joint surface.
A softened area is recognized from a portion separated by 10 mm to a portion separated by 10 mm, and the hardness thereof is a value of about 60 to 70% of that of the base material portion.
It can be determined that this is a portion affected by frictional heat. Therefore, the tensile strength of the softened region is significantly lower than the tensile strength of the base material portion, and the softened area is more likely to break than the base material portion.

The above phenomenon similarly occurs under other pressure welding conditions.

In the conventional friction welding method described above, each pressure welding condition, that is, friction pressure P1, upset pressure P2, friction time t.
1 and only the total deviation at the upset time t2 was measured (approximately 4 mm to 23.6 mm), and the friction welding was performed while measuring the total deviation and the friction deviation (that is, the reduced amount of the round bar after friction). Since the alumina particles that are finely crushed and deteriorated by heat compared to the base metal that accumulates on the joint surface during pressure welding cannot flow out to the outside in the radial direction, the softened area near the joint surface is affected by friction heat. Cannot flow out to the outside in the radial direction, and the above-mentioned problems occur.

Therefore, the present invention has as its technical problem to solve the above problems.

[0011]

In order to solve the above technical problems, the technical measures taken in the present invention are such that at least one of them comprises an aluminum alloy composite material in which ceramic particles or whiskers are compounded in an aluminum alloy. 1, a method of friction welding the second member,
While rotating the member at a constant speed, one of the first and second members is pressed toward the other member by a predetermined pressure to soften the contact surface by frictional heat generated at the contact surface of both members. Then, the rotational speed of the first member is reduced after setting the friction deviation margin to 3.5 to 7 mm, and is applied to one member when the first member is rotating at a constant speed when the first member is decelerated or stopped. By pressing the contact surface of one member toward the contact surface of the other member with a pressure larger than the pressure so that the total margin is 10 to 20 mm, the two contact surfaces in the softened state are solidified and joined. is there.

[0012]

According to the above technical means, friction welding is performed while measuring not only the total deviation but also the friction deviation, and the friction deviation is set to 3.5 to 7 mm and the total deviation is 10 to 20.
Since it is set to mm, when either the first member decelerates or the first member stops, one of the first and second members is pressed toward the other member to accumulate on the joint surface. The ceramic particles or whiskers finely crushed from the base metal part (that is, the part away from the joint surface) can flow out to the outside in the softened state, and the softened portion near the joint surface affected by friction heat Can flow to the outside in a softened state.

Here, if the frictional deviation margin is shorter than 3.5 mm, the above-mentioned action is not exhibited, and if it is longer than 7 mm, the yield is deteriorated. On the other hand, if the total margin is shorter than 10 mm, the above-mentioned action is not exhibited, and if it is longer than 20 mm, the yield is deteriorated.

As described above, since ceramic particles or whiskers finely crushed than the base material portion accumulated on the joint surface can flow out to the outside in the softened state, the space between the joint surface and the base material portion can be discharged. The difference in the content (volume%) of the ceramic particles or whiskers becomes small, and the difference in tensile strength and rigidity between the joint surface and the base material part also becomes small. In addition, since the softened part near the joint surface that is affected by frictional heat can flow out to the outside in the softened state, the hardness of the part several mm away from the joint surface (the part corresponding to the conventional softened zone) can be drastically increased. The tensile strength of the part several mm away from the joint surface does not decrease and becomes almost equal to the tensile strength of the base metal part, and the part several mm away from the joint surface is less likely to break.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

The present invention relates to a method of friction welding the first and second members, at least one of which is made of an aluminum alloy composite material in which ceramic particles or whiskers are composited in an aluminum alloy.

[Embodiment] A friction welding method for an aluminum alloy composite material according to this embodiment will be described with reference to FIGS. 1 and 2.

Two round rods 11 and 12 each having a diameter of 20 mm and a length of 100 mm and made of an aluminum alloy composite material in which 20 vol% of silicon carbide particles (whiskers) are dispersed in an AC8A aluminum alloy are machined. End face 1
1a and 12a were degreased and washed. Next, the vicinity of the end faces 11a and 12a of the round bars 11 and 12 was preheated at a temperature of 150 to 300 ° C.

Friction pressure P while rotating round bar 11 (first member) held by clamp 13 at a constant peripheral speed of 2 m / s
At 1 = 6 kgf / mm, the end surface 12a of the stationary side round bar 12 is pressed toward the end surface 11a of the rotating side round bar 11 so that both round bars 1
The vicinity of the contact surfaces 11a and 12a was softened by the frictional heat generated at the contact surfaces 11a and 12a of Nos. 1 and 12. At this time, the friction shift margin (that is, the reduction amount of the round bars 11 and 12 due to friction) was constantly measured, and the rotation speed of the round bar 11 was reduced when the friction deflection margin became 4 mm. Along with this, the pressure applied to the round bar 12 is increased, and the pressure (upset pressure) applied to the round bar 12 immediately after the rotation of the round bar 11 is stopped is P2 = 12 kg.
It was maintained at f / mm. The upset pressure may be maintained at P2 = 12 kgf / mm during deceleration of the round bar 11. When pressing the contact surface 12a of the round bar 12 toward the contact surface 11a of the round bar 11 with an upset pressure P2 = 12 kgf / mm, the total deviation (that is, the length of the round bar after the pressure welding and the pressure before the pressure welding). The difference from the length of the round bar) was constantly measured and both contact surfaces 11a and 12a in the softened state were solidified and joined when the total deviation was 16.3 mm.

3A and 3B are a plan view and an enlarged structure diagram of the joint portion 14 of the two round bars 11 and 12 joined by the friction welding method described above, respectively. In FIG. 3, 15 is an aluminum alloy and 16 is silicon carbide particles.
Further, FIG. 5 shows the hardness distribution and the volume ratio of silicon carbide particles in the range from the joining surface 17 of the round bar 11 to the portion separated by about 10 mm in the longitudinal direction.

Comparative Example A diameter of 20 mm and a length of 10 made of an aluminum alloy composite material in which 20 vol% of silicon carbide particles (whiskers) were dispersed and dispersed in an AC8A aluminum alloy.
Two 0 mm round bars 21 and 22 were machined to form round bars 21 and 22.
The end face of No. 2 was degreased and washed.

While rotating the round bar 21 (first member) at a constant peripheral speed of 2 m / s, the end surface of the stationary side round bar 22 is directed toward the end surface of the rotating side round bar 21 at a friction pressure P1 = 6 kgf / mm. It was pressed and melted in the vicinity of the contact surfaces by frictional heat generated at the contact surfaces of both round bars 21, 22. At this time, the friction deviation amount was constantly measured, and when the friction deviation amount became 2 mm, the rotation speed of the round bar 21 was decreased. Along with this, the pressure applied to the round bar 22 was increased, and the pressure (upset pressure) applied to the round bar 22 immediately after the rotation of the round bar 21 was stopped was maintained at P2 = 8 kgf / mm. When decelerating the round bar 21, the upset pressure is set to P2 =
It may be maintained at 8 kgf / mm. The contact surface of round bar 22
While pressing the upset pressure P2 = 8 kgf / mm toward the contact surface of No. 1, the total deviation is measured at all times, and when the total deviation becomes 5.7 mm, both contact surfaces in the softened state are measured. Solidified and joined.

4A and 4B are a plan view and an enlarged structure diagram of the joint portion 23 of the two round bars 21 and 22 joined by the friction welding method according to the comparative example, respectively. In FIG. 4, 24 is an aluminum alloy and 25 is a silicon carbide particle.
Further, the hardness distribution and the silicon carbide particles 2 in the range from the joining surface 26 of the round bar 21 to the portion separated by about 10 mm in the longitudinal direction.
The volume ratio of 5 is shown in FIG.

From FIG. 3, the round bars 11 and 12 according to this embodiment are shown.
In the joint portion 14 of, the base material portion (that is, 10 mm from the joint surface 17
It is recognized that the finely crushed silicon carbide particles are not accumulated and the round bars 11 and 12 are integrated to such an extent that the joining surface by pressure welding can hardly be confirmed. It means that the finely crushed silicon carbide particles accumulated in the joint portion 14 at the time of friction welding flow out in the radial direction in the softened state. Therefore, as shown in FIG.
The volume ratio (vol%) of the silicon carbide particles 16 hardly changes in the range from the joint surface 17 of the round bar 11 to a portion separated by about 10 mm in the longitudinal direction. The ratio (vol%) is almost equal to that of the base metal part.

On the other hand, as shown in FIG. 3, in the joint portion 23 of the round bars 11 and 12 according to the comparative example, finely crushed silicon carbide particles 25 are striped along the joint surface 26. It is recognized that the finely crushed silicon carbide particles 25 are accumulated in the joint portion 23 during friction welding.
Means that it did not flow in the radial direction in the softened state. Therefore, as shown in FIG.
Volume ratio (vol%) of the round bar 21 changes considerably in the range from the joining surface 26 of the round bar 21 to a distance of about 10 mm in the longitudinal direction,
The difference in the amount of change clearly appears in comparison with the present embodiment.

On the other hand, it can be seen from FIG. 5 that the hardness distribution in the range from the joining surface 17 of the round bar 11 to the portion separated by about 10 mm in the longitudinal direction is hardly changed. Specifically, the difference between the maximum hardness value and the minimum hardness value is 20 Hv or less. This means that the softened portion under the influence of the frictional heat in the vicinity of the joint surface 17 flows to the outside in the softened state while applying the upset pressure. On the contrary,
The hardness distribution in the vicinity of the joint surface 26 joined by friction welding according to the comparative example is significantly different from that of the present embodiment. That is,
The softened area is approximately 2 to 10 mm away from the joint surface, and the difference between the hardness of the joint surface and the hardness of the softened area is approximately 40 Hv.
Which is twice as large as that in this embodiment.

As shown above, in this embodiment,
Friction welding is performed while measuring not only the total deviation, but also the frictional deviation. Specifically, when the frictional deviation becomes 4 mm, the rotation speed of the round bar 11 is reduced, and the total deviation becomes 16.3 mm. Since the friction welding is completed when the round bar 11 is decelerated, the round bar 12 is pressed toward the round bar 11 when the round bar 11 is decelerated or stopped, so that the round bar 12 is finer than the base metal part accumulated at the joint 14. The crushed silicon carbide particles can flow out to the outside in the softened state, and the softened portion in the vicinity of the joint surface 17 affected by the friction heat can flow out to the outside in the softened state.

Since silicon carbide particles crushed finer than the base material portion accumulated at the joint portion 14 can flow out to the outside in the softened state, the volume of the silicon carbide particles between the joint portion 14 and the base material portion. The difference in proportion (vol%) becomes small, and the difference in tensile strength and rigidity between the joint portion 14 and the base material portion also becomes small.
In addition, since the softened portion in the vicinity of the joint surface 17 that is affected by frictional heat can flow out to the outside in the softened state, the hardness of the portion a few mm away from the joint surface 17 (the portion corresponding to the conventional softened region) is sharp. The tensile strength of the part several mm away from the joint surface 17 is substantially equal to the tensile strength of the base material without any decrease, and the part several mm away from the joint surface 17 is less likely to break.

In the present embodiment, the friction deviation amount is 4
However, the present invention need not be limited to this, and it is possible that the frictional deviation is 3.5 to 7 mm and the total deviation is 10 to 20 mm. For example, the above effect can be obtained.

In this embodiment, the case where the peripheral speed N of the round bar 11 is 2 m / s, the friction pressure P1 is 6 kgf / mm, and the upset pressure P2 is 12 kgf / mm is shown. There is no need to be limited, N = 2-4 m / s, P
It is applied when 1 = 4 to 8 kgf / mm and P2 = 6 to 24 kgf / mm. Here, P2 / P1 = 1.5 to 5 is desirable.

Further, in this embodiment, before the end surface 11a of the round bar 11 in contact with the end surface 12a of the round bar 12 (that is, before friction is applied) and the vicinity of the end surface 11a of the round bar 11 and the round bar. Since the vicinity of the end face 12a of 12 is preheated, the friction welding time can be shortened.

[0032]

The present invention has the following effects.

The ceramic particles or whiskers crushed finer than the base material portion accumulated on the joint surface can flow out to the outside in a softened state, and the volume ratio of the ceramic particles or whiskers between the joint surface and the base material portion. The difference between
Differences in tensile strength and rigidity between the joint surface and the base material portion are also reduced.

Further, the softened portion in the vicinity of the joint surface, which is affected by frictional heat, can flow out to the outside in the softened state,
The hardness of the part separated by mm (the part corresponding to the conventional softening region) does not drop sharply. As a result, a few
The tensile strength of the part separated by mm becomes substantially equal to the tensile strength of the base metal part, and the part separated by several mm from the joint surface becomes difficult to break.

[0035]

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a friction welding method according to this embodiment.

FIG. 2 is an explanatory diagram of a friction welding cycle according to this embodiment.

FIG. 3a is a plan view of a joint portion of two round bars joined by the friction welding method according to the present embodiment, and FIG. 3b is an enlarged structural diagram of the joint portion.

FIG. 4a is a plan view of a joint portion of two round bars joined by a friction welding method according to a comparative example, and FIG. 4b is an enlarged structural diagram of the joint portion.

FIG. 5 is a graph showing a hardness distribution and a volume ratio of silicon carbide particles in a range from a joint surface of a round bar to a portion separated by about 10 mm in a longitudinal direction in this example and a comparative example.

FIG. 6a is an enlarged structural diagram of a joint surface by a friction welding method according to a conventional technique, and FIG. 6b is an enlarged structural diagram of a base material portion.

FIG. 7 is a graph showing a hardness distribution in a range from a joint surface of a round bar to a portion approximately 25 mm apart in the longitudinal direction in the conventional technique.

[Explanation of symbols]

 11 Round Bar (First Member) 11a End Surface (Contact Surface) 12 Round Bar (Second Member) 12a End Surface (Contact Surface) 14 Joining Part 15 Aluminum Alloy 16 Silicon Carbide Particles (Whiskers) 17 Joining Surface

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junji Sugishita 162-1 Matsugashima, Nagashima-cho, Kuwana-gun, Mie Prefecture 2 (72) Noboru Egami 8-16 Fujiyamadai, Kasugai-shi, Aichi

Claims (3)

[Claims] 1. A method of friction-welding at least one of an aluminum alloy composite material in which ceramic particles or whiskers are composited to an aluminum alloy, wherein the first member is rotated at a constant speed. While pressing one of the first and second members toward the other member with a predetermined pressure, the frictional heat generated at the contact surfaces of the two members softens the two contact surfaces to cause friction. After setting the deviation margin to 3.5 to 7 mm, the rotation speed of the first member is reduced to
When decelerating the member or stopping the first member, the contact surface of the one member is directed toward the contact surface of the other member with a pressure larger than the pressure applied to the one member when the first member rotates at a constant speed. A method for friction welding of an aluminum alloy composite material, characterized in that both contact surfaces in a softened state are solidified and joined after being pressed by pressing to set the total deviation to 10 to 20 mm. 2. The peripheral speed of rotation of the first member is 2 to 3 m / s.
And the pressure applied to one of the first and second members when the first member is decelerating or when the first member is stopped is applied to the one member when the first member rotates at a constant speed. The method for friction welding of an aluminum alloy composite material according to claim 1, wherein the pressure applied to the member is set to 2 to 5 times. 3. The friction welding method for an aluminum alloy composite material according to claim 1, wherein the vicinity of the contact surfaces of both members is preheated before rotating the first member.