JPH0255684A - Different material joint - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance and the joining strength of a different material joint by controlling a range of a junction part heated at a specific temperature to a prescribed distance or below from a joining interface. CONSTITUTION:At the time of bringing a member 2 consisting of stainless steel, etc., to solid phase joining to a member 1 consisting of a Zr compound stock, etc., a range of a junction part heated at a temperature of >=800 deg.C is limited to a distance of <=10mm from joining end faces 3, 4, respectively, and joining is executed. In this case, pressing force of the prescribed pressure range is allowed to work on vertical end faces 3, 4 of the members 1, 2, and by setting a transformation temperature of the member 1 as a boundary, heating is executed by a heat cycle by upper and lower suitable temperature width. Since ranges 7, 8 of a heating junction part are limited to <=10mm, an expanse of heat affected zones 5, 6 of the junction part decreases. In such a way, since generated thickness of an intermetallic compound of the junction part decreases, the corrosion resistance and the joining strength of the junction part are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a dissimilar material joint using a solid phase joining method.

[Conventional technology] Solid phase welding is a concept that includes pressure welding, ultrasonic welding, friction welding, explosion welding, diffusion welding, etc., but the conventional solid phase welding method cannot join dissimilar metal joints. As shown in FIG. 3(a), it is customary to perform this on a plane perpendicular to the joining direction. That is, the vertical end surfaces 3 and 4 of the members 1 and 2 are abutted, the abutted portions are heated by resistance heating by direct energization, and then a pressing force P is applied in the axial direction to join them. At this time, the heat affected zones 5 and 6 undergo plastic deformation and expand as shown in FIG. 3(b).

[Problems to be Solved by the Invention] Therefore, in conventional dissimilar metal joints, there is a problem in that the heat-affected zone expands significantly, causing changes in the metal structure and deteriorating mechanical properties and corrosion resistance.

Further, since the amount of plastic deformation cannot be limited to the vicinity of the joint interface, it is not possible to maintain high adhesion at the joint interface, and the joint strength is unstable and low.

Therefore, the present invention aims to stabilize and increase the joint strength by minimizing the spread of the heat-affected zone and ensuring a sufficient amount of plastic deformation near the joint interface. The purpose is to provide a joint.

[Means for Solving the Problems] In the dissimilar metal joint according to the present invention, when making a joint of dissimilar metal materials using a solid phase joining method, the joint part is heated to 800°C or higher, and the range of the joint part is heated to a joining interface. Each of these is limited to 10 dragons or less.

[Function] In the dissimilar material joint according to the present invention, since the range of the joint parts heated to 800°C or higher is limited to 10 mm or less from the joint interface, the spread of the heat-affected zone is small, and the joint strength is stabilized. High strength can be achieved. This is because by limiting the distance from the bonding interface, the thickness of the fragile intermetallic compound layer generated at the bonding portion can be made as thin as possible.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of a dissimilar material joint formed by joining under superplastic transformation, which is a type of diffusion joining method. In this example, member 1
A Zr-based material (including pure zirconium and its alloy) is used for the member 2, and a stainless steel material (SUS304L) is used for the member 2. Then, the vertical end faces 3.4 of the member 1.2 are butted together with a pressing force in the range of 0.01 to 1.0 kg/+11112, and electricity is applied directly to the abutted portion to heat this part, so that the transformation temperature of Zr is 862 ° C. Give the required number of human cycles at an appropriate temperature range above and below.

FIG. 2 shows an example of a heat cycle pattern. The peak temperature is 1027°C, the bottom temperature is 677°C, and the heating/cooling rate when passing the transformation temperature is 20°C/sec.
It is said that Moreover, the number of cycles is 1 to 5 times.

By applying such a heat cycle, the Zr-based material undergoes transformation superplasticity, and therefore, under this superplastic state, a load P is applied to members 1 and 2 to join them together under pressure. As shown in FIG. 1(b), a part of the Zr-based material 1 that has undergone transformation superplasticity is removed from the bonding interface and becomes solid and fixed, so that it is finally machined to a predetermined size.

In joining under such transformation superplasticity, the range 7.8 of the heated joint can be limited to 10 or less, so the spread of the heat affected zone 5.6 is smaller than in the conventional case.

According to experiments, the relationships between the pressing force (kg/mu2), the thickness (μm) of the intermetallic compound layer, and the bonding strength (kg/mm2) were as shown in Table 1.

In the case of the conventional example shown in Table 1, Table 2, and Figure 3, the thickness of the intermetallic compound layer is 90 μm and the bonding strength is 25 kg/++us” or less, whereas in the case of the present invention, the thickness is 50 μm or less and 26 μm or less, respectively.
) cg/mm2 or more, and an improvement in bonding strength was observed,
And there is little variation.

Further, in an accelerated corrosion resistance test using a boiling nitric acid aqueous solution containing 1.0 g/N of Cr6+, extremely excellent corrosion resistance was shown as shown in Table 2.

Note: In the table, O indicates no selective corrosion at the joint interface, Δ indicates selective corrosion at the joint interface, and × indicates severe selective corrosion at the joint interface.

Note that the present invention is applicable not only to Zr-based materials but also to corrosion-resistant iron-based materials and materials that cannot be fusion-welded, such as Ti.

This can be similarly applied to V, etc. The same applies not only to bar joints but also to pipe joints. moreover,
The shape of the bonding interface may be a Taber shape.

[Effects of the Invention] As described above, the dissimilar material joint according to the present invention has the effect of having high joint strength and corrosion resistance, and stable joint strength.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are a diagram showing the configuration of a dissimilar material joint according to the present invention and a state diagram during joining, Figure 2 is a diagram showing an example of a heat cycle pattern, and Figures 3 (a) and (b) are conventional FIG. 2 is a configuration diagram of an example and a state diagram at the time of joining. 1゜2...Joining member 3゜4...Vertical end surface

Claims (1)

[Claims] A joint made of dissimilar metal materials produced by a solid-phase joining method, characterized in that the range of the joint parts heated to 800° C. or higher is 10 mm or less from the joint interface.