KR20010057954A - Creep testing apparatus of specimen with welding part - Google Patents

Abstract

PURPOSE: A creep testing device for a workpiece formed with a welded portion is provided to obtain a large volume of data for various different materials, small-sized materials, or local parts of a material by a single test in a short time by using a testing piece manufactured with a small size. CONSTITUTION: A creep testing device for a workpiece formed with a welded portion includes upper and lower fixing dies(1,2) formed with a through hole in the center and fixing a workpiece in the center, a load transmission die(3) inserted into the through hole of the upper fixing die to transmit a load to the workpiece, a displacement measuring die(8) inserted in the through hole of the lower fixing die to be displaced by the deformation of the workpiece, a pressing element(30) for applying a load from an upper part of the load transmission die, a strain gauge(9) mounted below the displacement measuring die for measuring the displacement of the displacement measuring die, and a heating furnace(18) formed with a plurality of through holes at to and bottom surfaces correspondingly to each other to be inserted by the upper and lower fixing dies, wherein the upper and lower fixing dies are received in the heating furnace in such a manner that an upper part of the upper fixing die is exposed to the top surface and a lower part of the lower fixing die is exposed to the bottom surface.

Description

Creep testing apparatus of specimen with welding part

The present invention relates to a creep test apparatus for evaluating creep of a metal material in a short time, and in particular, it is possible to test a small test piece manufactured to measure creep in a region where a characteristic of the metal material is locally changed, such as a welded part. The present invention also relates to a creep test apparatus capable of simultaneously measuring a plurality of test pieces.

In general, many of the highly functional materials are locally different in the properties of the material, and quantitatively evaluating such differences in local properties serves as an important factor in terms of material development and reliability.

On the other hand, most structures are manufactured through a process of welding a plurality of materials. However, since the weld is heated to a high temperature, a local metallic change occurs around the weld, and the mechanical properties are also complicated. For this reason, quantitative evaluation of the different characteristics around the welds is essential to ensure the stability of the structure and to develop welded steels and materials.

On the other hand, when the material is used in a high temperature environment, in particular, when it is used for a long time in an environment of 40% or more of the melting temperature of the material, deformation may gradually occur over time, and the air supply may be subject to breakage accidents. do.

For this reason, materials used at high temperatures must have good creep properties and accurate creep properties must be identified to evaluate the development of the material or the life of the product.

In order to evaluate the mechanical properties of these localized parts and creep characteristics at high temperatures, conventionally, tensile test pieces have been manufactured and subjected to a tensile test. However, due to the shape of the test pieces, only the weld part or the creep of the local part to be evaluated is properly Evaluating is difficult in practice. In addition, the conventional method that has been used to evaluate the creep characteristics takes a few months to several years, and the conventional creep test apparatus has a disadvantage that only one test piece can be evaluated per unit.

The present invention is provided to solve the problems of the prior art as described above, the mechanical properties and creep characteristics of the weld or the local changes in the site using a test piece of 0.5mm ~ 1mm, diameter of about 10mm The purpose of the present invention is to provide a creep test apparatus capable of simultaneously evaluating the characteristics of a plurality of specimens in a short time.

1 is a cross-sectional view of a creep test apparatus of a small test piece is formed welded according to an embodiment of the present invention,

2 is a plan view of the creep test apparatus shown in FIG.

3 is a perspective view showing the upper and lower fixing rods, load transfer rods, displacement measuring rods and other components shown in FIG.

4 is a cross-sectional view of the upper and lower fixing rods, load transfer rods, displacement measuring rods and other components shown in FIG.

5 is a detailed view showing the test piece shown in FIG. 4 in detail;

6 is a detailed view showing the lever and the rotating hinge and other components shown in FIG.

FIG. 7 is a cross-sectional view illustrating the push rod and the load transfer rod illustrated in FIG. 6.

8 is data measured by a creep test apparatus for a small test piece having a welded part according to the present invention.

♠ Explanation of symbols on the main parts of the drawing ♠

1: upper holder 2: lower holder

3: load transfer rod 4: test piece

6: first steel ball 7: second steel ball

8: displacement measuring rod 9: electric displacement gauge

14 weight 18 electric furnace

21: thermometer measuring instrument 27: load center holding jaw

According to the present invention for achieving the object as described above, in the creep test apparatus for measuring the creep of the test piece, a through hole is formed in the center, and the upper and lower fixtures for fixing the test piece in the middle, and formed in the upper fixture A load carrier inserted into the through hole to transfer the load to the test piece, a displacement gauge inserted into the through hole formed in the lower holder and displaced according to the deformation of the test piece, and pressurizing the load from the upper part of the load carrier. A means, a displacement meter installed under the displacement measuring unit to measure displacement of the displacement measuring unit, and a plurality of through holes corresponding to each of the upper and lower surfaces are formed so that the upper and lower fixing rods are inserted into the through holes. Exposed to an upper surface, and a lower portion of the lower holder is exposed to a lower surface; The creep test apparatus including a furnace for receiving the lower support unit is provided.

Further, according to the present invention, a steel ball is located between the load carrier and the test piece, and between the test piece and the displacement measuring table.

In addition, according to the present invention, a protrusion is formed on an upper surface of the load carrier, and a groove is formed on the bottom of the pressing means to match the protrusion.

In the following, with reference to the accompanying drawings, a preferred embodiment of the creep test apparatus of the small test piece formed welded according to the present invention will be described in detail.

1 is a cross-sectional view of a creep test apparatus of a small test piece having a welded portion according to an embodiment of the present invention, FIG. 2 is a plan view of the creep test apparatus shown in FIG. 1, and FIG. 3 is shown in FIG. 1. 4 is a perspective view showing the upper and lower fixing rods, the load transmitting rods, the displacement measuring rods, and other components, and FIG. 4 is a cross-sectional view of the upper and lower fixing rods, the load transmitting rods, the displacement measuring rods, and other components, and FIG. 5 is shown in FIG. Figure 6 is a detailed view showing the test piece in detail, Figure 6 is a detailed view showing the lever and the rotating hinge and other components shown in Figure 1, Figure 7 is a cross-sectional view showing the push rod and the load transfer rod shown in Figure 6, 8 is the data measured by the creep test apparatus of the small test piece with a welded part which concerns on this invention.

1 to 5, in the creep test apparatus of the test piece, a test piece 4 having a thickness of 0.5 mm and a diameter of 10 mm is placed between the upper holder 1 and the lower holder 2, and the upper holder 1 and By fastening the fixing bolt 5 connecting the lower holder 2, the upper holder 1 and the lower holder 2 are fixed in a state in which the test piece 4 is accommodated.

In particular, a hole is formed in the center of the upper fixing stand (1) in the longitudinal direction, the load transfer rod (3) is inserted into this hole can be moved in the vertical direction, the central hole of the lower fixing stand (2) along the longitudinal direction Is formed, and the displacement measuring rod 8 is inserted into the hole and can move in the vertical direction.

In order to minimize deformation at high temperature, the smallest outer diameter of the upper fixing stand 1 should be at least five times the central hole diameter, and in the case of the lower fixing stand 2, the outer diameter should be at least seven times the central hole diameter. do. In other words, as shown in FIG. 4, the ratio of D1 / D2 should be 5 or more, and the ratio of D3 / D4 should be 7 or more.

In addition, the locking jaw 1a of the upper holder 1 is processed to a size larger than the diameter of the hole processed in the upper lid 19 of the electric furnace 18, so that the upper holder 1 is formed on the upper lid 19. Even when inserted into the hole, the upper lid 19 is caught in the locking jaw 1a of the upper holder 1 and is always positioned in the vertical direction.

In this state, when the load transfer rod 3 inserted in the upper stator 1 receives a load from the upper portion, the load is the first steel ball 6 located between the load transfer rod 3 and the test piece 4. Is transmitted to the test piece 4, and the test piece 4 is deformed according to the magnitude of the load. Here, the reason why the 1st steel ball 6 is located is in order to concentrate the load on the test piece 4 to one point.

On the other hand, as shown in Figure 7, the load center rod (27) is formed on the upper surface of the load transfer rod (3) so that the load is applied in a constant vertical direction, the load center holding jaw (27) It matches with the hole formed in the center part of the pressure reduction rod 12 which contacts the upper surface of the load transfer rod 3, and presses. Therefore, when the pressure reducing rod 12 matched with the load center holding jaw 27 moves downward, the load applied to the load transfer rod 3 is always transmitted only in the vertical direction.

When the test piece 4 is deformed by such a load, the deformation amount is transmitted to the electric displacement meter 9 fixed to the displacement gauge support 11 by the displacement measuring rod 8 and finally recorded on the displacement recorder 22. . Meanwhile, the second steel ball 7 is positioned between the test piece 4 and the displacement measuring rod 8, and the center point of the first steel ball 6 and the center point of the second steel ball 7 are placed on a vertical line. Located.

On the other hand, the upper and lower fixtures (1, 2) and the components contained therein can be mounted to the number of holes processed in the upper lid 19, it is possible to test the creep of several test pieces (4) at once.

6 shows a load transmission mechanism, even if a weight 14 having a low weight P1 acts on the weight support 13, two levers 16, six rotary hinges 17, and a plurality of weights. By the action of the lever support 25, the pressing rod 12 acts as a load P2. This may be represented as in Equation 1.

P2 = P1 (L1 / L2) (L3 / L4)

Where L is the distance from the lever base to the rotating hinge, P1 is the weight of the weight, and P2 is the load on the push rod.

By varying the length of each lever 16, even if a low weight 14 acts, the load on the push rod 12, the load transfer rod 3 and the test piece 4 becomes large.

On the other hand, the upper and lower fixtures (1, 2) and the components contained therein are fixed by the upper lid 19 and the lower lid 20, the test piece 4 by the electric furnace 18, the predetermined temperature atmosphere Exist within. Then, the test piece 4 is subjected to creep deformation by the load transmission mechanism. In addition, the lower fixing table 2 has a temperature sensing hole 10 formed near the test piece 4, and a thermometer 26 is inserted into the temperature sensing hole 10 to sense the temperature of the test piece 4. , The temperature is recorded by the thermometer 21.

In addition, the device support 23 is fixed to the lower lid 20, the device level holding system 24 is used to maintain the level of the entire test equipment.

The operation relationship of the creep test apparatus of the small test piece in which the welded part comprised as mentioned above is demonstrated in detail.

First, the test piece 4 is seated on the upper surface of the lower fixing table 2, the upper fixing table 1 is matched to the upper surface of the lower fixing table 2, and then the fixing bolt 5 is tightened, so that the test piece 4 is It is to be located between the upper fastening (1) and the lower fixing (2) integrally fastened. Then, the first steel ball 6 is inserted into the test piece 4 through the hole in the center of the upper fixing stand 1, and the load transfer rod 3 is inserted into the hole of the upper fixing stand 1. In this way, the assembled test piece 4, the upper fixing stand (1), the lower fixing stand (2), the upper steel ball (6), the load transfer rod (3) is inserted into the hole of the upper lid (19).

In this state, a very low weight weight 14 is placed on the weight support 13 so that a small load is not applied to the test piece 4, and then the hole and the load transfer rod of the pressure reducing rod 12 are placed. The load center retaining jaw 27 of (3) is matched. Next, the second steel ball 7 is inserted through the hole of the lower fixing stand 2, the displacement measuring rod 8 is inserted therein, and then the second steel ball (using the tension of the spring of the electric displacement gauge 9) is used. 7) make contact with the underside of the specimen (4) and fix the electric displacement meter (9) to the displacement support (28).

After completing the above operation for the plurality of test pieces as many as the number of holes processed in the upper lid 19, power is supplied to the electric furnace 18, and the temperature of the test piece 4 is raised to a target temperature. Let's do it. At this time, when the temperature shown in the thermometer measuring instrument 21 through the thermometer 26 reaches the target temperature, the weight 14 of the weight P1 as much as the weight to be calculated as P2 in the equation (1) When placed on, the specimen 4 creep deformation over time and the deformation is transmitted to the displacement recorder 22 through the second steel ball 7, the displacement measuring rod 8, and the electrical displacement meter 9. do.

8 is a result of measuring creep at the same temperature with the same test piece. The load applied to the test specimen is the largest load 1, the smallest load 3, and the load 2 is the size between the load 1 and the load 3.

At this time, when the creep is generated, it can be seen that the load is generated in the order of the larger order.

As described in detail above, since the creep test apparatus of the small test piece having the welded part according to the present invention uses the small test piece, as a single test on a small material and a material having a locally different property such as a weld part within a short time, The advantage is that a lot of data can be obtained.

Although the technical idea of the creep test apparatus of the small test piece with the welded part of the present invention has been described above with the accompanying drawings, this is illustrative of the best embodiment of the present invention and is not intended to limit the present invention. In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims (3)

In the creep test apparatus for measuring the creep of the test piece, A through hole is formed in the center, and the upper and lower fixtures for fixing the test piece in the middle; A load transmitter inserted into the through hole formed in the upper stator to transfer a load to the test piece; A displacement measuring base inserted into the through hole formed in the lower fixing stand and displaced according to the deformation of the test piece; Pressing means for applying a load at the top of the load carrier; A displacement meter provided below the displacement measurement stand and measuring a displacement of the displacement measurer; A plurality of through holes corresponding to the upper and lower surfaces are formed so that the upper and lower holders are inserted into the through holes, the upper part of the upper holder is exposed to the upper surface, and the lower part of the lower holder is heated to accommodate the upper and lower holders to be exposed to the lower surface. Creep test apparatus comprising a furnace. The method of claim 1, A creep test device, characterized in that a steel ball is located between the load carrier and the test piece, and between the test piece and the displacement measuring table. The method according to claim 1 or 2, A protrusion is formed on the upper surface of the load carrier, the bottom of the pressing means creep test apparatus, characterized in that the groove is formed to match the protrusion.