JPS62107004A - Manufacture of capsule for hip - Google Patents

Abstract

PURPOSE:To prevent the occurrence of defects in weld zones when four members are assembled into a capsule by welding, by carrying out welding at positions away from the corners so as to relieve stress produced in the weld zones. CONSTITUTION:A metallic capsule for HIP is composed of a bottom wall, a tubular wall and a top wall having a degassing pipe. At this time, a bottom wall 1, a tubular wall 2, a top wall 3 and a degassing pipe 4 having shapes obtd. by dividing a capsule along planes which meet at right angles to an axial direction at positions away from the top and bottom are prepd. and those four elements are welded in vacuum or an inert gaseous atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a capsule filled with powder such as a superalloy when solidifying (sintering) the powder by HIP.

(Prior art) HIP has recently begun to be widely used as a technology for solidifying powders such as superalloys, but capsules filled with powder are usually made of thin sheets of mild steel or stainless steel, as shown in Figures 8 and 9. ,
Bottom wall 20 serving as the bottom plate. Cylinder wall 21, top wall 22 serving as the upper lid
and a small-diameter degassing pipe 23, which is located at the center of the top wall 22 and communicated with the inside, are assembled by welding. TIG welding is usually used for this welding.
In order to facilitate deformation during HIP, thin plates and pipes with a thickness of less than a few inches are used.

(Problems to be Solved by the Invention) As is clear from FIGS. 8 and 9, the welded portions 24 are the corners where the four members intersect, and as shown in FIG. Air is sucked in during welding, making the weld metal part brittle and prone to micro defects such as pinholes. To explain this point in more detail, since the materials of the four members are thin, even if welding is done from the outside, the welding part and the inner base metal in the vicinity will be in a high temperature state and oxidize due to the heat of the welder. . And the scale generated by this oxidation is a quaternary scale even if the material is stainless steel.
As shown in the photo, the situation is quite severe. usually,
Before use, capsules are cleaned to remove foreign matter adhering to their inner surfaces, but scale formed by high-temperature oxidation cannot be completely removed.If this is mixed into the powder, the required characteristics of the powder solidifying material may be affected. It will cause a loss.

In addition, by filling the powder into the capsules shown in Figures 8 and 9,
When IP is applied, deformation as shown in FIG. 1O occurs. At this time, a large stress builds up in the highly rigid part of the corner, which is the welding part 24, due to the deformation of the capsule, and in combination with the aforementioned brittle structure and micro defects, gas as a pressure medium intrudes during HIP. It may inhibit the solidification and sintering of the powder.

(Means for Solving the Problems) The present invention, when welding and assembling the above-mentioned four members (elements) constituting the capsule, separates the welded part from the corner part, so that the welded part can be removed at the time of HIP. This was done with the purpose of reducing the stress applied to the machine and preventing the pressure medium from entering during HIP, and the following configuration was adopted as a means to achieve this purpose. That is, in forming a metal capsule consisting of a bottom wall, a cylinder body wall, and a top wall having a degassing pipe, the present invention provides for The four elements of the bottom, cylinder body, top, and degassing pipe are prepared and are assembled by welding, which are separated by a plane perpendicular to the axial direction at slightly distant positions.

(Example) FIG. 1 is a sectional view of a capsule obtained by the method of the present invention. In the figure, 1 is a bottom part, 2 is a barrel part, 3 is a top part, and 4 is a degassing pipe part. In a capsule consisting of a bottom wall, a barrel wall, and a top wall with a degassing tube, these four elements are located at a position slightly further away from the bottom wall and top wall, at a position where the barrel rests, and at a distance from the top wall of the degassing tube. It has a shape that is divided along a plane perpendicular to the axial direction (not in a strict sense). Therefore, the dividing planes are the welded portions 5, and in other words, these welded portions 5 are located slightly away from the corner portions 6 of the capsule. In the figure, l is the distance from the end surface of the corner part 6 to the welding part 5, and 5 < j! <35 (am) is preferable; if it is more than 35 mm, it is economically disadvantageous; if it is less than 5 mm, it is no different from the conventional one, and the object of the present invention cannot be achieved. Note that the materials of the four elements used in the present invention include stainless steel, mild steel, etc., and the welded portion 5 is formed with a groove etc. according to a usual method and is performed by TIG welding or the like. Next, during welding and for a while after welding (until the temperature of the welded part decreases), welding is carried out while flowing an inert gas such as 8R into the capsule, or in a state where it is replaced with an atmosphere of ^R. Alternatively, the entire capsule may be welded in a vacuum or in an inert gas atmosphere. This type of welding is carried out because the material is a thin plate, so the welding heat heats the welded area and its vicinity to a high temperature and oxidizes it, making the welded area brittle and allowing Ar gas to enter during HIP. This is to prevent scale from being mixed into the powder and damaging its mechanical properties.

The present invention will be described below along with more specific examples and comparative examples. As shown in Figure 1, SUS with an outer diameter of 101.6φ
A bottom plate (bottom part 1), a top cover (top part 3), and a degassing pipe part 4 cut out from a SUS 304 plate were TIG-welded to a 304TP steel pipe (tube body part 2) at each weld part 5. The distance between the corner 6 of the bottom l and the welded part 5 of the cylinder body 2 is 1.
5 mm, the distance from the corner 6 of the top 3 to the weld 5 of the cylinder body 2 is 1 (In), the distance from the weld 5 between the top 3 and the degassing pipe 4 is l (1 m, and the material of each part is The wall thickness used was that of 3 dragons.

FIG. 2 shows a conventional capsule of the same size and shape as the capsule of the present invention, which was manufactured by a conventional method for comparison.

Figure 3 shows the case where welding is carried out in an atmospheric oxidizing atmosphere,
It is a capsule for testing the condition of welded parts when carried out under an inert gas atmosphere, and has an outer diameter of 101.6φ5US.
304 TP steel pipe with Wl as shown in the figure.

Take the groove of W2, and apply Ar gas to the inner surface of Wl at 81/mi.
W2 was welded from the outside in an oxidizing atmosphere of the air while flowing at a rate of n, and the oxidation state near the weld on the inside was compared. The results are as shown in the enlarged photographs (x1) in Figures 4 and 5. Figure 4 shows the weld in W2, and Figure 5 shows the weld in Wl, with the inner surface of the former being in a normal oxidizing atmosphere. In the latter case, the welded part is severely oxidized, whereas it is clearly seen that oxidation is prevented in the latter case.

Next, in order to confirm the effects of the present invention, a super heat resistant alloy was used as the powder, and a low cycle fatigue test was conducted on the HIP solidified material. The table below is Ni-based super superalloy AF115 alloy)
This is a powder produced by argon atomization. A capsule for HIP was manufactured by the method shown in FIGS. 1 and 2.

(Next leaf) Both HIPs are 1160℃ x 1000 k+r
/cA
h /AC solution treatment and aging were performed to obtain test materials A (Fig. 1) and B (Fig. 2). In the fatigue test, the parallel part was 7φ
Using a smooth specimen of No. 161, strain rate at 760°C, ε=
The test was conducted under strain-controlled oscillation conditions of 0.4%/S. The results are shown in FIG.

As shown in FIG. 6, the fatigue life of the HIP solidified material obtained using the capsule of the present invention is high (and its variation is small).On the other hand, the conventional capsule has a large variation,
In extreme cases, the lifespan is 1/lθ or less compared to healthy materials. This is because, as shown in the micrograph (X100) in Figure 7, in the case of conventional capsules, Ar gas, the pressure medium, entered from the welded part during HIP and existed as a bore, resulting in a notch effect. It had a short lifespan.

From the above, it was found that the present invention is a very effective method in terms of fatigue life reliability.

(Effects of the invention) The capsules produced by the method of the invention have the following properties during HIP:
The stress applied to the welded part can be reduced, and the occurrence of defects in the welded part can be prevented, which prevents the pressure medium from entering during HIP.
It is excellent in that it does not impair the fatigue properties of IP solidified materials and improves the reliability of important characteristic values of HIP solidified materials of various other materials.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a capsule manufactured by the method of the present invention, Figure 2
The figure is a cross-sectional view of a conventional capsule, Figure 3 is a cross-sectional view of a comparative test capsule, Figure 4 is a comparison of the oxidation state of the W2 weld in Figure 3, and Figure 5 is the W1 weld in Figure 3. FIG. 6 shows a fatigue test graph, and FIG. 7 shows a microphotograph showing defects in the HIP solidified material using the conventional capsule shown in FIG. 2. 8 and 9 are explanatory diagrams of a conventional capsule, FIG. 1O is an explanatory diagram of a deformed capsule after HIF', and FIG. 11 is an explanatory diagram of air entrapment during welding. 1... Bottom, 2... Cylinder body, 3... Top, 4...
- Degassing pipe part, 5... Welding part, 6... Corner part. Patent applicant: Kobe Steel, Ltd. Figure 8
Figure 9 Figure 1o Figure 11 Figure 1 Figure 211 Figures 3-4
Figure 5 Figure 6 Fa, tLJut lj, je-, AIIcoycJ
tx) Proceeding City Authorization (Method) February 19, 1985

Claims (3)

[Claims] (1) When forming a metal capsule consisting of a bottom wall, a cylindrical body wall, and a top wall having a degassing pipe, there are two positions: a position slightly closer to the cylindrical body wall than the bottom wall and the top wall, and a position slightly closer to the cylindrical body wall than the top wall of the degassing pipe. 2. A HIP capsule characterized by preparing four elements, a bottom, a barrel, a top, and a degassing pipe, which are separated from each other in a plane orthogonal to the axial direction, and assembling these four elements by welding. manufacturing method. (2) The scope of claims characterized in that welding is carried out while an inert gas is flowing inside the welding area until the temperature of the welded part falls during and after welding, or while the inside is replaced with an inert atmosphere. 2. A method for producing a HIP capsule according to item 1. (3) HIP according to claim 1, characterized in that welding is performed in a vacuum or in an inert gas atmosphere.
method for manufacturing capsules for