JP2002113583A - Method for friction pressure welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a large joined strength by preventing or suppressing the formation of a layer of deformed spheroidal graphite. SOLUTION: The method is characterized by the fact that an iron-base metallic member or a Ni-base metallic member is inserted 10 on a pressure welding face 11 of a spheroidal graphite cast iron 1 in a friction pressure welding of the spheroidal graphite cast iron 1 and a steel member 2, that the pressure joining fact 16 of the spheroidal graphite cast iron 1 is made concave in the friction pressure welding of the spheroidal graphite cast iron 1 and a steel member 2, and that the iron-base metallic member on a Ni-base metallic member is inserted into the pressure joining face of the spheroidal graphite cast iron and the pressure joining face 16 of the spheroidal graphite cast iron is made concave in the friction pressure welding of the spheroidal graphite cast iron 1 and the steel member 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for friction welding a spheroidal graphite cast iron to a steel material.

[0002]

2. Description of the Related Art Friction welding is a processing method in which one material to be joined is rotated, the other is fixed, and joining is performed by frictional heat generated by pressing against each other. This friction welding can be used in a wide range because it can be joined in a solid phase. Friction welding is used in, for example, mechanical parts such as automobile parts, tools, hydraulic equipment, and electric parts. However, friction welding using a casting as one material is not used because the strength of the casting base material is greatly deteriorated due to deformation of the graphite shape.

[0003] When a solid round bar-shaped spheroidal graphite cast iron 1 and a steel material 2 having a pressed surface formed by lathing are joined by friction welding, the joint 3 shown in FIG. The deformed layer 4 is formed in which the graphite (graphite) in the spheroidal graphite cast iron is deformed and flattened by the pressing force. The deformed layer 4 in which the spheroidal graphite is deformed flat remains in the joint without being discharged to the burrs 5 because the plastic deformation of the spheroidal graphite cast iron side is small during friction welding. As a result, the deformable layer 4 on the side of the spheroidal graphite cast iron is positioned with the flat graphite surface substantially parallel to the joint 3. The deformed layer 4 of graphite is one of the causes of reducing the strength of the joint. This fact is well known among those involved in friction welding. For example, “Friction welding of spheroidal graphite cast iron to mild steel” by Horie, Huang, Konishiki and Hiratsuka of Iwate University (Japan Foundry Society No. 132
(See p. 38 of the Annual National Meeting Lecture Summary).

Several proposals have been made for friction welding of cast iron materials. Japanese Patent Publication No. 3-72392 discloses a method of friction-welding steel and cast iron having graphite. This method controls the distribution density of graphite in cast iron and controls the metal structure such as carburization at the joint. Further, Japanese Unexamined Patent Publication No.
85469, JP-A-9-126220, JP-A-9-122936, JP-A-9-123723
In any of the structures disclosed in Japanese Patent Laid-Open Publication No. H10-205, the member to be joined by friction welding is a hollow material (pipe).
The reason for using the hollow material is that the deformable layer 4 described with reference to FIG.
This is for avoiding the formation of.

[0005]

In the friction welding of spheroidal graphite cast iron and a steel material, the spheroidal graphite in the spheroidal graphite cast iron deforms flat by friction welding and remains at the joint. Such flat deformed graphite has the problem that the strength of the joint is reduced, and the greater the amount of deformation of the graphite, the lower the strength of the joint. An object of the present invention is to provide a method of friction welding a spheroidal graphite cast iron and a steel material which can prevent or suppress the formation of the graphite deformable layer and obtain a high bonding strength.

[0006]

According to a first aspect of the present invention, in the friction welding of spheroidal graphite cast iron and a steel material, an iron-based metal material or a nickel-based metal material is inserted into a press-contact surface of the spheroidal graphite cast iron. And

According to this means, the iron-based metal material of the insert material has the same iron as the main component of the spheroidal graphite cast iron and the steel material, and the nickel-based metal material is the spheroidal graphite cast iron and the steel material. Solid solution with iron, the main component of the material,
Does not degrade the bondability of the joint. Therefore, good bonding can be performed in a state where the formation of the deformation layer is small.

[0008] The means of the second invention is characterized in that in the friction welding of the spheroidal graphite cast iron and the steel material, the pressure contact surface of the spheroidal graphite cast iron is made concave.

In this means, since the pressure contact surface of the spheroidal graphite cast iron is formed in a concave shape, it becomes difficult to form a deformed layer at the center of the joint. The reason for this is that the central part of the spheroidal graphite cast iron does not contribute much to the friction and pressurization at the start of rotation, but the pressure is applied slightly after the peripheral deformation progresses, and the frictional heat is sufficiently transmitted. Thus, it is considered that the friction welding operation is completed before or when the deformation layer is formed.

[0010] The means of the second invention is preferably used in combination with the means of the first invention. As a result, the effects of both inventions appear synergistically, a deformed layer is not formed, good joining is performed, and a strong joint is obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The materials to be joined were FCD450 as spheroidal graphite cast iron and S45C of carbon steel for machine structure as a steel material. In general friction welding, joining is performed by the following joining process. First, materials to be joined are pressed together and one of them is rotated to generate frictional heat. The friction surface and its vicinity become high temperature by the friction heat. The friction surface and its vicinity undergo plastic deformation at high temperatures, and a part of the deformed portion is discharged as a flash outside the substantial joint. As a result of the plastic deformation being performed at the contact portion, the clean surfaces of the materials are joined to each other to complete the joining.

According to the present invention, in selecting an insert material to be used, an active metal which is expected to promote heat generation during friction and is expected to be joined without deforming the material is used for the insert material. It is conceivable that a metal having good bondability is used for the insert material. The insert materials having the former function are the active metals titanium (Ti), niobium (Nb) and molybdenum (M
o), tantalum (Ta), zirconium (Zr), and magnesium (Mg). The material used as the insert material having the latter function is iron (Fe).
And nickel (Ni). As a result, the former idea was found to be inappropriate, but was described as a comparative example for reference.

As the material to be joined, as shown in FIG. 1, the spheroidal graphite cast iron material 1 formed into a stepped round bar and the carbon steel material 2 having the same shape are prepared. The press contact surfaces 11 and 12 to be joined were turned into a plane perpendicular to the direction of the axis. As shown in the figure, the insert material 10 was placed over the pressure contact surface 11 on the side of the spheroidal graphite cast iron material 1 and fastened and fixed with a thin metal wire 13.

The friction welding was performed as follows. As the compression cycle of friction welding, a brake type shown in FIG. 2 was applied. In practical use, it is not necessarily limited to the brake type, and the well-known inertia type (the friction pressure P1 and the upset pressure P
2 may be the same pressure and rotationally driven by inertial force) or a pressure proportional control type (pressure increases with friction time). The welding conditions were as shown in Table 1. The joining material subjected to friction welding was formed on a tensile test piece 14 shown in FIG.

[0015]

[Table 1]

Table 2 shows the insert materials used, their thicknesses, and the results of the joining results expressed in three stages of ◎ (very good), （(good), and × (bad). .

[0017]

[Table 2]

Further, the metal structure of the joined portion 15 was examined. In Comparative Examples 1 to 6, it was recognized that the heat generation phenomenon as expected during friction welding was not observed, and the insert material was not discharged to the burrs, but remained as small pieces at the joint. . In the central part on the side of the spheroidal graphite cast iron material, the graphite was deformed flat, and it was found that there was no effect of using the insert material. In Examples 1 to 4, there is no effect of promoting the generation of frictional heat, but it is recognized that an intermediate layer exists between the two joining materials, and the entire joint area 1
5, it was recognized that graphite was slightly deformed at the center of the spheroidal graphite cast iron material 1 side of the joint. Since the deformation area of the graphite is narrow,
The decrease in strength is small and practical depending on the application.

From the above results, as shown in FIG. 4, the depth D of the spheroidal graphite cast iron material 1
Examples 5 to 8 were prepared by providing a concave portion (about 0.5 mm) provided with the concave portion 16 and performing friction welding corresponding to the above-described Examples 1 to 4 using this. This is shown in Table 3 of items substantially similar to Table 1.

[0020]

[Table 3]

As shown in Table 3, good results were obtained. It should be noted here that changing the friction time and the thickness of the insert material changes the tensile strength.The longer the friction time, the better, and the thicker the insert material. is there. For example, if the insert material is iron (thickness 50
μm, 100 μm), in the case of friction welding with a friction pressure of 30 MPa and an upset pressure of 60 MPa, when the friction time is 20 seconds and 60 seconds, as shown in FIG. It is recognized that the thicker the insert material, the greater the tensile strength of the joint. When the insert material is iron, the thickness is 100 μm, and the friction time is 60 seconds, the maximum tensile strength is 400 MPa.
And this value is the tensile strength of the base material FCD450 of 470.
It is about 85% of MPa. Also, from the result of a similar test in which nickel was used for the insert material, the thickness was 100%.
μm, when the friction time is 60 seconds, the tensile strength is 400M
Pa was confirmed.

In addition to the above embodiment, when friction welding is performed in the same manner as that shown in FIG. 4 except that the insert material 10 is removed, the deformed layer of graphite becomes considerably smaller than when the recess 16 is not provided. Was confirmed.

[0023]

According to the first aspect of the invention, the main component of the iron-based metal material of the insert material is the same as the main component of the spheroidal graphite cast iron and the steel material. Since it forms a solid solution with the main components of the graphite cast iron and the steel material, the joining is favorably performed in a state where the deformed layer is little formed, and the strength of the joint is improved. The invention described in claim 2 is
Providing the concave portion has an effect that it is difficult to form a deformable layer at the center of the joint. According to the third aspect of the present invention, the effects of both the first and second aspects of the invention are exhibited synergistically, a deformed layer is not formed, good bonding is performed, and a strong bonding portion is formed. Is obtained.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional front view showing the shape of a test piece before friction welding in Examples and Comparative Examples of the present invention.

FIG. 2 is a graph showing a compression cycle of a brake type friction welding machine applied to an example of the present invention and a comparative example.

FIG. 3 is a front view showing a state in which a test piece after pressure contact is processed into a tensile test piece in Examples and Comparative Examples of the present invention.

FIG. 4 is a longitudinal sectional front view of a main part showing a state before pressure welding of Examples 11 to 14 of the present invention.

FIG. 5 is a graph showing a difference in tensile strength when the friction time and the thickness of the insert material are changed in the example of the present invention.

FIG. 6 is a front view showing a state where friction welding is performed by a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spheroidal graphite cast iron material 2 Iron and steel material 3 Joining part 4 Graphite deformation layer 5 Burr 10 Insert material 11 Pressure contact surface 12 Pressure contact surface 13 Fine metal wire 14 Tensile test piece 15 Joint

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mikio Saito 3-12 Kanbei-cho, Otsu-ku, Himeji-shi, Hyogo Pref. No.12, Nijigi Co., Ltd., Himeji East Plant (72) Inventor Masatoshi Aritani 3-2-2, Kashinodai, Nishi-ku, Kobe-shi, Hyogo F-term (reference) 4E067 AA02 AA04 AB02 AB05 AD02 BG00 DA13

Claims (3)

[Claims] 1. A method for friction welding of a spheroidal graphite cast iron and a steel material, wherein an iron-based metal material or a nickel-based metal material is inserted into a pressed surface of the spheroidal graphite cast iron. 2. A method for friction welding of a spheroidal graphite cast iron and a steel material, wherein a pressing surface of the spheroidal graphite cast iron has a concave shape. 3. The friction welding method according to claim 1, wherein the pressure welding surface of the spheroidal graphite cast iron has a concave shape in the friction welding of the spheroidal graphite cast iron and a steel material.