JP3646742B2 - Low alloy steel shaft or joining method of steel shaft and titanium aluminide rotating body - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a low alloy steel shaft or a joining method of a steel shaft and a titanium aluminide rotating body, and particularly, due to a change in crystal structure that occurs during cooling after heating, such as low alloy steel or ordinary steel. The present invention relates to a method for joining a material having a large constitution change and a material having a small ductility such as titanium aluminide.
[0002]
[Prior art]
In general, materials called new materials such as ceramics and titanium aluminide have excellent characteristics not found in conventional metals such as ordinary steel. However, since these materials have low ductility, not only welding but also friction welding, cracks may occur during pressure welding or subsequent cooling, and sufficient strength can be obtained. Some materials are not. For example, in the case of titanium aluminide, titanium aluminide is an intermetallic compound, so that it is difficult to weld and bond with dissimilar metals, and silver brazing has been used so far. After that, a method was proposed in which ordinary steel was joined by a joining method such as electron beam welding with a heat-resistant alloy having good joining properties to titanium aluminum as a mediating member, and then the mediating member and titanium aluminum were friction welded.
[0003]
Such steel is joined to ordinary steel by a joining method such as electron beam welding using a heat-resistant alloy such as Incoloy 903, which has good joining properties with titanium aluminum, as an intermediate member, and then the intermediate member and titanium aluminum are friction welded. For example, Japanese Patent Laid-Open No. 2-157403 discloses a method for doing this. In this example, a steel shaft and a heat-resistant alloy hollow insert material are joined, and then the insert material and a titanium aluminum turbine wheel are friction welded.
[0004]
In the example of JP-A-2-157403, ordinary steel and a heat-resistant alloy insert are joined by electron beam welding or the like, and the heat-resistant alloy insert is hollow in order to reduce the amount of heat transfer to the shaft.
[0005]
FIG. 4 shows a conventional method of joining a titanium aluminum turbine wheel disclosed in the above publication. a is a titanium aluminum turbine wheel of a turbocharger, and b is a steel shaft. c is a hollow insert material interposed between the titanium aluminum turbine wheel a and the steel shaft b. The insert material c and the shaft b are first joined (e) by a joining method such as an electron beam, and then the insert c and the turbine wheel a are joined (f) by friction welding.
[0006]
Further, in order to solve the above-described problems of the conventional technique, the applicant of the present application is as shown in FIG. 3, as shown in FIG. 3, the joining surface of either the titanium aluminide member 2 and the low alloy steel member or the ordinary steel member 1. And a step of fitting a mediator material 3 thicker than the depth of the concave portion 4 into the concave portion 4. The titanium aluminide member 2 and the low alloy steel member or the ordinary steel member 1 are rotated relative to each other for friction. Invented a method of joining titanium aluminide and low alloy steel or ordinary steel, which has a step of pressing and joining while heating and a step of naturally cooling these integrated members, and filed a patent application (patent application) Hei 7-81013 (unpublished)).
[0007]
[Problems to be solved by the invention]
However, the silver brazing described above has low strength, and becomes weaker as the temperature rises, so that the reliability is not sufficient.
[0008]
In addition, even in joining by friction welding, ordinary steel and a heat-resistant alloy insert material must be joined by electron beam welding or the like, and the heat-resistant alloy insert material must be hollow in order to reduce the amount of heat transfer to the shaft.
[0009]
In the technology of Japanese Patent Application No. 7-81013 (unpublished) relating to the application of the present applicant, a concave portion is provided on the joining surface of one of a titanium aluminide member and a low alloy steel member or a normal steel member, and a mediating material is provided in the concave portion. Even in joining that is pressed while heating by friction, for the convenience of providing a recess on the joining surface, the outer diameter must be larger only at the edge of the recess than the product dimension, and the amount of processing after joining is increased. Increase significantly.
There were problems such as.
[0010]
The present invention has been devised in view of the above problems, and easily and wastefully uses a low alloy steel shaft or steel shaft having a large change in constitution due to cooling after heating and a titanium aluminide rotating body having a small ductility. An object of the present invention is to provide a joining method for joining together.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, in the first invention of the low alloy steel shaft or the method of joining the steel shaft and the titanium aluminide rotating body of the present invention, the low alloy steel shaft or the steel shaft and the titanium aluminide rotation A joining method with the body,
Placing the heat-resistant alloy member provided with a hole on the low alloy steel shaft or the joining surface of the steel shaft;
Welding the portion of the hole with a heat-resistant alloy and fixing the low alloy steel shaft or the steel shaft and the heat-resistant alloy member integrally;
The low alloy steel shaft or the steel shaft and the titanium aluminide rotating body are relatively rotated and pressed while being heated by friction to be joined.
[0012]
In the second invention, the heat-resistant alloy member is formed in a disc shape.
[0013]
In the third invention, a low alloy steel shaft or a method of joining a steel shaft and a titanium aluminide rotating body, wherein a heat resistant alloy is formed in a disc shape on the joining surface of the low alloy steel shaft or the steel shaft. And a step of covering the low alloy steel shaft or the steel shaft and the titanium aluminide rotating body by relatively rotating and pressing and joining them while heating by friction.
[0014]
According to the above-described joining method, the heat-resistant alloy member provided with the hole is placed on the joining surface of the low alloy steel shaft or the steel shaft having an outer diameter substantially the same as the shaft diameter of the titanium aluminide rotating body, After the part is welded with a heat-resistant alloy and the low-alloy steel shaft or the steel shaft and the heat-resistant alloy member are fixed together, or the heat-resistant alloy is applied to the joint surface of the low-alloy steel shaft or the steel shaft. After covering the plate with welding by welding, the low alloy steel shaft or the steel shaft and the titanium aluminide rotating body are rotated relative to each other and pressed and joined while being heated by friction. Since the difference in volume change between ordinary steel or low alloy steel and titanium aluminide that occurs during cooling is absorbed, it is possible to prevent the occurrence of cracks or the like at the joint.
[0015]
If a low alloy steel shaft or a steel shaft having an outer diameter substantially the same as the shaft diameter of the titanium aluminide rotating body is joined, the machining cost after friction welding can be minimized.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 and 2 are side views in which a part of a joint according to an embodiment of the present invention is cut away.
In FIGS. 1 and 2, 11 is a low alloy steel shaft or a plain steel shaft, which is one member to be joined, and 12 is a titanium aluminide rotating body, which is the other member to be joined. Reference numeral 13 denotes a heat-resistant alloy member having a hole 14 in the center placed on the joining surface of the low alloy steel shaft or the plain steel shaft 11. It is a heat resistant alloy in which an alloy steel shaft or a plain steel shaft 11 is fixed. Further, reference numeral 16 shown in FIG. 2 denotes a heat-resistant alloy member in which the joint surfaces of the low-alloy steel shaft and the ordinary steel shaft 11 are covered with a weld plate in a disk shape instead of the heat-resistant alloy member 13.
[0017]
The low-alloy steel shaft and the ordinary steel shaft 11 and the titanium aluminide rotating body 12 are joined by using a friction welding apparatus (not shown). The heat-resistant alloy member 13 provided with the hole 14 or the heat-resistant alloy member 15 that is covered with a metal plate by welding is joined as a medium.
[0018]
【Example】
Hereinafter, examples of the present embodiment will be described in detail.
In the joining test, chromium molybdenum steel (SCM435 steel) is used for one member to be joined, titanium aluminide compound is used for the other member, and the dimensions of chromium molybdenum steel (low alloy steel member) 1 are 15 mm in outer diameter and length. The dimensions of the titanium aluminide compound 2 were 30 mm and the outer diameter was 15 mm and the length was 25 mm. In addition, at first, the heat-resistant alloy member 13 provided with the holes 14 shown in FIG. 1 was used for joining, and the heat-resistant alloy member 13 was a disk of nickel alloy material (NCF600-JIS standard) having a thickness of 2 mm. Next, it joined using the member 16 made from a heat-resistant alloy which was covered by welding as shown in FIG. In addition, the nickel alloy material (Inco Weld82) marketed was used for the welding rod used for these welding. In addition, welding was performed by general Tig welding, and fixed or metallized.
[0019]
In the first joining test, that is, the joining test using the heat-resistant alloy member 13 provided with the holes 14,
Rotation speed: 2000rpm
Frictional pressure and offset: 294 MPa, 1.5 mm
Upset pressure and time: 392 MPa, 6 sec
Under this condition, after performing twice, the tensile test of the joining test piece was performed at room temperature, and the result is as follows.
[0020]
The test results were confirmed to have a tensile strength of 270 MPa and 350 MPa.
In the second joining test, that is, the joining test using the heat-resistant alloy member 16 coated with welding by welding, a height of 1.5 mm to 2.0 mm is formed on the joining surface of the low alloy steel member (SCM435 steel). The metal plating was applied. After this metal plating, the friction welding was performed twice under the same conditions as the first bonding test, and then the tensile test of the bonding test piece was performed at room temperature. The results are as follows. is there.
[0021]
The test results were confirmed to have tensile strengths of 414 MPa and 480 MPa. This strength is substantially equal to that of the titanium aluminide base material, and the joint efficiency is close to 100.
[0022]
【The invention's effect】
As described above, the present invention is a low alloy to be joined even when joining a low alloy steel shaft or a normal steel shaft having a large volume change due to cooling after heating and a titanium aluminide rotating body having a small ductility. Relative rotation by placing a heat-resistant alloy member with holes on the joint surface of an alloy steel shaft or ordinary steel shaft and welding the holes to fix them, or by mediating the heat-resistant alloy members coated with welding by welding Because it is heated and pressed by friction and joined, the heat-resistant alloy absorbs the difference in volume change at the time of cooling, can prevent the occurrence of cracks etc., and obtain sufficient strength It has excellent effects such as
[Brief description of the drawings]
FIG. 1 is a side view in which a part of a joint according to an embodiment of the present invention is cut away.
FIG. 2 is a side view in which a part of a joint according to another embodiment of the present invention is cut away.
FIG. 3 is a side view showing a joint portion of Japanese Patent Application No. 7-81013 relating to an existing application.
FIG. 4 is a cross-sectional view showing a joint portion by a conventional method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Low alloy steel or ordinary steel member 2 Titanium aluminide member 3 Mediating member 4 Recess 11 Low alloy steel shaft and ordinary steel shaft 12 Titanium aluminide rotating body 13 Heat-resistant alloy member 14 Hole 15 Welded portion 16 Welded by welding Heat-resistant alloy member

Claims (3)

A low alloy steel shaft or a joining method of a steel shaft and a titanium aluminide rotating body,
Placing the heat-resistant alloy member provided with a hole on the low alloy steel shaft or the joining surface of the steel shaft;
Welding the portion of the hole with a heat-resistant alloy and fixing the low alloy steel shaft or the steel shaft and the heat-resistant alloy member integrally;
The low alloy steel shaft or the steel shaft and the titanium aluminide rotating body are relatively rotated and pressed while being heated by friction and joined together.
A low alloy steel shaft or a joining method of a steel shaft and a titanium aluminide rotating body. The low-alloy steel shaft or the steel shaft and the titanium aluminide rotating body according to claim 1, wherein the heat-resistant alloy member is formed in a disk shape.   A method of joining a low alloy steel shaft or a steel shaft and a titanium aluminide rotating body, wherein a heat-resistant alloy is welded in a disk shape to the joining surface of the low alloy steel shaft or steel shaft. A low alloy steel shaft or a steel shaft, and a step of relatively rotating the low alloy steel shaft or the steel shaft and the titanium aluminide rotating body and pressing them while being heated by friction. Bonding method with titanium aluminide rotating body.

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