JP2018200188A - Thermal fatigue test method, test piece, thermal fatigue test apparatus - Google Patents

Abstract

To obtain a thermal fatigue test method, a test piece, and a thermal fatigue test apparatus capable of suppressing relaxation of restraint of the test piece in the course of the thermal fatigue test as compared to a case where V-shaped blades are press-fitted into both end portions of the test piece from a direction orthogonal to the direction of elongation and contraction of the test piece to restrain both end portions of the test piece by a jig.SOLUTION: In the restraining step, a shim member is brought into contact with the restraining portion 12 (both end portions) of the test piece 10 from the longitudinal direction to restrain the restraining portion 12 of the test piece 10 to the jig. In the expansion restraining process, heating and cooling are repeated to constrain the longitudinal expansion and contraction of the test piece 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thermal fatigue tester, a test piece, and a thermal fatigue test apparatus.

  Patent Document 1 includes a test piece having an evaluation portion with a small cross-sectional area, and a low expansion material having a thermal expansion coefficient smaller than that of the test piece in the test temperature range and having no temperature singularity at which the thermal expansion coefficient changes rapidly. Two holders are prepared and a thermal fatigue test method for materials used at high temperatures is described.

JP 2003-35644 A

  Conventionally, the test piece used for the thermal fatigue test method is elongate. And the both ends of the test piece were restrained by the jig | tool by press-fitting a V-shaped blade to the both ends of the test piece from the direction orthogonal to the expansion / contraction direction of the test piece. For this reason, the part where the blade was press-fitted at both ends of the test piece was plastically deformed. Therefore, a thermal fatigue test was performed and the test piece expanded and contracted, so that the plastically deformed area was widened and the test piece was loosely restrained during the test.

  The subject of this invention is compared with the case where the both ends of a test piece are restrained to a jig | tool by press-fitting a V-shaped blade into the both ends of a test piece from the direction orthogonal to the expansion-contraction direction of a test piece. It is to suppress loosening of the test piece during the test.

  In the thermal fatigue test method according to claim 1 of the present invention, the both end portions of a long test piece having an evaluation portion having a smaller cross-sectional area than the both end portions at the center portion are set to have a thermal expansion coefficient with respect to the test piece. Is a thermal fatigue test method that is performed by constraining to a different jig, a constraining step of constraining both ends of the test piece to the jig by bringing a constraining member into contact with the both ends from the longitudinal direction of the test piece; An expansion / contraction restraint step of repeatedly constraining the expansion and contraction of the test piece in the longitudinal direction by repeating heating and cooling in a state where the both ends are constrained by the jig.

  According to the above configuration, in the restraining step, the restraining member is brought into contact with both ends from the longitudinal direction to restrain the both ends of the test piece to be restrained by the jig. Then, in the expansion and contraction restraining step, heating and cooling are repeated in a state where both ends are constrained by the jig, thereby restraining the expansion and contraction of the test piece in the longitudinal direction.

  Here, the both ends of a test piece are restrained by the jig | tool by making a restraint member contact both ends from a longitudinal direction. As a result, compared with the case where both ends of the test piece are restrained by the jig by pressing the V-shaped blades into the both ends of the test piece from the direction perpendicular to the expansion / contraction direction of the test piece, It is possible to suppress loosening of the restraint of the test piece.

  The thermal fatigue test method according to claim 2 of the present invention is the thermal fatigue test method according to claim 1, wherein the both ends have a first surface facing the opposite side to the evaluation portion side in the longitudinal direction. And a second surface facing the evaluation portion side in the longitudinal direction, respectively, and the jig has a first facing surface facing the first surface and a second facing the second surface. An opposing surface is formed, and in the restraining step, the first surface and the first opposing surface are opposed to each other, and the second surface and the second opposing surface are opposed to each other. And a shim member as the restraining member is inserted into a gap formed between the first opposed surface and between the second surface and the second opposed surface.

  According to the above configuration, in the restraining step, the shim member for filling the gap generated between the first surface and the first facing surface and between the second surface and the second facing surface is inserted into the gap. . In this manner, the restraint portion of the test piece is restrained by the jig by filling the gap by inserting the shim member into the gap. For this reason, even when the length of the test piece varies, the restraint portion of the test piece can be restrained by the jig.

  A thermal fatigue test method according to a third aspect of the present invention is the thermal fatigue test method according to the second aspect, wherein, at the both end portions, between the first surface and the first opposing surface, and the second surface. And a gap between the second facing surface and the second facing surface, respectively, and in the restraining step, at one end, the gap formed between the first surface and the first facing surface is filled. The shim member is inserted into a gap formed between the second surface and the second facing surface, and is inserted from a direction opposite to the insertion direction of the shim member, and at the other end, the first surface The shim member that fills the gap formed between the first facing surface and the first facing surface is inserted in the gap formed between the second surface and the second facing surface, opposite to the insertion direction of the shim member. It is characterized by being inserted from the direction.

  According to the above configuration, in the restraining step, the shim member that fills the gap formed between the first surface and the first facing surface is formed between the second surface and the second facing surface at one end. It is inserted from a direction opposite to the insertion direction of the shim member to be inserted into the gap. In addition, at the other end of the shim member, the shim member that fills the gap generated between the first surface and the first facing surface is inserted into the gap generated between the second surface and the second facing surface. Insert from the opposite direction to the insertion direction. Thus, by inserting the shim members, the end of the test piece is displaced in the insertion direction of the shim members with respect to the jig as compared with the case where all the shim members are inserted into the gap from the same direction. Can be suppressed.

  A test piece according to claim 4 of the present invention is a long test piece used in the thermal fatigue test method according to any one of claims 1 to 3, and is formed at a central portion in a longitudinal direction. A cylindrical evaluation portion, a rectangular parallelepiped shape formed at both ends in the longitudinal direction, the first surface facing the side opposite to the evaluation portion side in the longitudinal direction, and the evaluation in the longitudinal direction And a restraint portion having a second surface facing the portion side.

  According to the said structure, the restraint part currently formed in the both ends of the longitudinal direction of a test piece is made into the rectangular parallelepiped shape. For example, the maximum length of the restraint portion may be determined in the orthogonal direction orthogonal to the longitudinal direction of the test piece. In such a case, the constraining portion is a rectangular parallelepiped extending in a direction different from the direction in which the maximum length is determined, so that the constraining portion is circular when viewed from the longitudinal direction. The area with the second surface can be increased.

  A thermal fatigue test apparatus according to claim 5 of the present invention is a thermal fatigue test apparatus used in the thermal fatigue test method according to any one of claims 1 to 3, wherein A first facing surface facing the first surface facing the side opposite to the evaluation portion side at both ends of the test piece, and a second facing surface facing the second surface facing the evaluation portion side at both ends of the test piece A gap formed between the first surface and the first facing surface, and between the second surface and the second facing surface, and the both end portions A plurality of shim members for restraining the jig by the jig, and a heating / cooling tester for repeating heating and cooling in a state where the both ends are restrained by the jig.

  According to the above configuration, the gap generated between the first surface of the test piece and the first opposing surface of the jig, and between the second surface of the test piece and the second opposing surface of the jig. By filling, both ends are constrained by a jig. As a result, compared with the case where both ends of the test piece are restrained by the jig by pressing the V-shaped blades into the both ends of the test piece from the direction perpendicular to the expansion / contraction direction of the test piece, It is possible to suppress loosening of the restraint of the test piece.

  According to the present invention, as compared with the case where both ends of the test piece are restrained by the jig by press-fitting V-shaped blades into the both ends of the test piece from the direction orthogonal to the expansion / contraction direction of the test piece. It is possible to suppress loosening of the restraint of the test piece during the test.

It is the disassembled perspective view which showed the test piece and jig | tool used for the thermal fatigue test method which concerns on embodiment of this invention. It is the partially exploded perspective view which showed the test piece, shim member, and jig | tool used for the thermal fatigue test method which concerns on embodiment of this invention. It is the perspective view which showed the test piece, shim member, and jig | tool used for the thermal fatigue test method which concerns on embodiment of this invention. (A) (B) It is sectional drawing which showed the test piece and jig | tool used for the thermal fatigue test method which concerns on embodiment of this invention. (A) (B) It is sectional drawing which showed the test piece, shim member, and jig | tool used for the thermal fatigue test method which concerns on embodiment of this invention. It is the front view which showed the test piece and jig | tool used for the thermal fatigue test method which concerns on embodiment of this invention. It is the front view which showed the test piece used for the thermal fatigue test method which concerns on embodiment of this invention, the side view, the top view, and the bottom view. (A) (B) It is the perspective view which showed the heating-cooling testing machine used for the thermal fatigue test method which concerns on embodiment of this invention. It is drawing which showed the thermal expansion amount used for the test piece and jig | tool used for the thermal fatigue test method which concerns on embodiment of this invention with the graph. It is drawing which showed the heating and cooling conditions of the thermal fatigue test method which concerns on embodiment of this invention with the graph. In the thermal fatigue testing method concerning the embodiment of the present invention, it is the figure which showed the thermal strain of the test piece with the graph. It is the disassembled side view which showed the test piece and thermal fatigue testing apparatus which are used for the thermal fatigue testing method which concerns on the comparison form with respect to the thermal fatigue testing method which concerns on embodiment of this invention. It is the side view which showed the test piece and thermal fatigue testing apparatus which are used for the thermal fatigue testing method which concerns on the comparison form with respect to the thermal fatigue testing method which concerns on embodiment of this invention.

(overall structure)
An example of a thermal fatigue test method, a test piece, and a thermal fatigue test apparatus according to an embodiment of the present invention will be described with reference to FIGS. In addition, the arrow H shown in the figure is the vertical direction of the jig used in the thermal fatigue test method and indicates the vertical direction, the arrow D is the depth direction of the jig and indicates the horizontal direction, and the arrow W is The horizontal direction is the width direction of the jig. In the thermal fatigue test, both ends of the long test piece to be evaluated are restrained by a jig having a different thermal expansion coefficient (linear expansion coefficient) from the test piece, and heating and cooling are repeated. Then, the thermal strain generated by the difference in thermal expansion between the test piece and the jig (generated by restraining the expansion and contraction in the longitudinal direction of the test piece) is concentrated on the evaluation part formed between the both ends of the test piece. The thermal fatigue life of the test piece is determined by the number of heating and cooling cycles when the evaluation part is broken.

  First, the test piece 10 and the thermal fatigue test apparatus 30 used for the thermal fatigue test method of this embodiment are demonstrated. In addition, about the test piece 10, it demonstrates by the attitude | position restrained by the jig | tool 32 which comprises the thermal fatigue test apparatus 30. FIG.

[Test piece 10]
The test piece 10 is formed using an aluminum alloy (JIS-AC2B), and has a long shape extending in the vertical direction as shown in FIG. The thermal expansion coefficient of the aluminum alloy is 21.5 × 10 ⁻⁶ [/ K]. The graph of FIG. 9 shows the thermal expansion curve of the aluminum alloy. The horizontal axis of this graph is temperature [° C.], and the vertical axis is the coefficient of thermal expansion [%]. It can be seen that the amount of thermal expansion increases as the temperature increases.

  Moreover, when viewed from the depth direction and the width direction, the test piece 10 is, in the width direction and the depth direction, with respect to a straight line C1 that passes through the center of gravity G1 of the test piece 10 and extends in the vertical direction, as shown in FIG. It has a symmetrical shape. Further, when viewed from the depth direction and the width direction, the test piece 10 is symmetrical in the vertical direction with respect to a straight line C2 that passes through the center of gravity G1 and extends in the width direction and a straight line C3 that passes through the center of gravity G1 and extends in the depth direction. ing.

  In the present embodiment, the length of the test piece 10 in the vertical direction (L1 in the figure) is 64 [mm]. The test piece 10 includes a restraining portion 12 formed at both ends in the vertical direction (longitudinal direction), an evaluation portion 14 formed at the central portion in the vertical direction, an evaluation portion 14 and the restraining portion 12. And a connecting portion 16 for connecting the two.

The evaluation unit 14 has a columnar shape extending in the vertical direction, and has a smaller cross-sectional area than the restraint unit 12 and the connection unit 16. In the present embodiment, the diameter (E1 in the figure) is 4 [mm], and the length (E2 in the figure) is 6 [mm]. And the cross-sectional area of the evaluation part 14 is 12.6 [mm < ² >].

  The constraining portion 12 has a rectangular parallelepiped shape, and in this embodiment, the length in the vertical direction (L2 in the figure) is 5 [mm], and the length in the width direction (L3 in the figure) is 12 [mm]. The length in the depth direction (L4 in the figure) is 10 [mm].

  The restraining portion 12 has a first surface 12A facing the evaluation portion 14 side in the vertical direction (longitudinal direction of the test piece 10) and a second surface 12B facing the evaluation portion 14 side in the vertical direction. Is formed. This 2nd surface 12B is divided | segmented by the connection part 16, and is formed in a pair.

The area of the first surface 12A is 120 [mm ² ], and the area of the pair of second surfaces 12B is 60 [mm ² ]. That is, the area of the first surface 12 </ b> A and the area of the pair of second surfaces 12 </ b> B are larger than the cross-sectional area of the evaluation unit 14. In other words, the cross-sectional area of the evaluation part 14 is made smaller than the cross-sectional area of the restricting part 12.

  The connecting portion 16 has a smaller cross-sectional area than the restraining portion 12. The connecting portion 16 is formed between the rectangular parallelepiped portion 16A extending from the restraining portion 12 toward the evaluation portion 14, and between the rectangular parallelepiped portion 16A and the evaluation portion 14, and the cross section gradually changes. And a deformed portion 16B. In the present embodiment, the length in the width direction (L5 in the drawing) of the rectangular parallelepiped portion 16A is 6 [mm], and the length in the depth direction (L4 in the drawing) of the rectangular parallelepiped portion 16A is 10 [mm]. .

[Thermal fatigue testing device 30]
The thermal fatigue test apparatus 30 includes a jig 32 for restraining the test piece 10, shim members 40 and 46, and a heating and cooling test machine 60 that repeatedly heats and cools the test piece 10 and the jig 32. ing.

-Jig 32
The jig 32 is formed using Incoloy 904 alloy (trade name HRA904, manufactured by Hitachi Metals), and has a long shape extending in the vertical direction as shown in FIG. The coefficient of thermal expansion of Incoloy 904 alloy is 3.0 × 10 ⁻⁶ [/ K]. That is, the jig 32 is formed of a material having a low thermal expansion coefficient as compared with the material used for the test piece 10. The graph of FIG. 9 shows the thermal expansion curve of Incoloy 904 alloy. From this graph, it can be seen that the Incoloy 904 alloy has a lower coefficient of thermal expansion in a wide temperature range than the aluminum alloy.

  The jig 32 has a symmetrical shape in the width direction and the depth direction with respect to a straight line C10 extending in the vertical direction through the center of gravity G2 of the jig 32 when viewed from the depth direction and the width direction (see FIG. 1). Further, when viewed from the depth direction and the width direction, the jig 32 has a first opposing surface 36A described later with respect to a straight line C20 extending in the width direction through the center of gravity G2 and a straight line C30 extending in the depth direction through the center of gravity G2. The shape is symmetrical in the vertical direction except for the inclination of the second facing surface 36B (see FIG. 1).

  And the jig | tool 32 is a member by which the space 34 by which the test piece 10 is arrange | positioned is formed in the rectangular parallelepiped block extended to an up-down direction, as FIG. 1 shows. In the present embodiment, the length of the jig 32 in the vertical direction (L11 in the figure) is 78 [mm], the length in the width direction (L12 in the figure) is 22 [mm], and the length in the depth direction. (L13 in the figure) is 10 [mm]. The vertical length of the space 34 (L14 in the figure) is 68 [mm].

  The space 34 extends in the vertical direction and penetrates in the depth direction. The space 34 has a pair of first spaces 36 in which the restraining portions 12 of the test piece 10 are disposed, and a second space 38 formed between the pair of first spaces 36.

  The first space 36 has a rectangular parallelepiped shape extending in the width direction. In this embodiment, the length of the first space 36 in the width direction (L15 in the drawing) is 12 [mm], and the vertical direction. The length (L16 in the figure) is 9 [mm].

  The first space 36 includes a first facing surface 36A facing the first surface 12A of the restraining portion 12 of the test piece 10 and the restraining portion 12 of the test piece 10 in a state where the test piece 10 is disposed in the space 34. It is formed including a pair of second facing surfaces 36B facing the second surface 12B.

  Further, as shown in FIG. 4A, the first facing surface 36 </ b> A has a depth side portion in the depth direction positioned below the depth direction front side portion as viewed from the width direction. In this way, it is inclined with respect to the depth direction. Similarly, the second opposing surface 36B is inclined with respect to the depth direction so that the portion on the back side in the depth direction is positioned below the portion on the near side in the depth direction when viewed from the width direction. ing. The gradient (degree of inclination with respect to the horizontal plane) of the first opposed surface 36A and the second opposed surface 36B is 1/100. Note that the gradient shown in the figure is exaggerated so that the gradient can be easily understood.

  4B, the test piece 10 is placed in the space 34 of the jig 32, and the test piece 10 is placed with the center of gravity G1 of the test piece 10 and the center of gravity G2 of the jig 32 overlapped. There is a gap between the first surface 12A of the ten restraining portions 12 and the first facing surface 36A. Furthermore, a gap is generated between the second surface 12B of the restraining portion 12 of the test piece 10 and the second facing surface 36B. The distance in the vertical direction of these gaps is about 2 [mm].

Further, in the first facing surface 36A, the area of the portion facing the first surface 12A of the test piece 10 is 120 [mm ² ], and the second surface 12B of the test piece 10 is in the pair of second facing surfaces 36B. The area of the part that faces is 60 [mm ² ].

  Moreover, the 2nd space 38 is made into the rectangular parallelepiped shape extended in an up-down direction, as FIG. 1 shows. In the present embodiment, the length in the width direction of the second space 38 (L17 in the figure) is 6.4 [mm]. In the width direction, a clearance of about 0.2 mm is provided between the test piece 10 and the jig 32.

-Shim members 40, 46-
Two shim members 40 are provided as plate-like members, and as shown in FIGS. 2 and 3, the shim members 40 have a rectangular shape when viewed in the vertical direction. The shim member 40 is disposed between the first surface 12A of the test piece 10 and the first facing surface 36A of the jig 32. Further, in the shim member 40, the gradient of the plate surface 40A on the first facing surface 36A side is 1/100 with respect to the opposite surface, and as shown in FIGS. As viewed from the direction, it is inclined so as to come into contact with the first facing surface 36A. The shim member 40 fills a gap generated between the first surface 12A and the first facing surface 36A.

  In the present embodiment, as shown in FIG. 2, the shim member 40 has a length in the width direction (L21 in the figure) of 12 [mm] and a length in the depth direction (L22 in the figure) of 15 [mm]. The thickness is about 2 [mm].

  Two shim members 46 are provided as plate-like members, and as shown in FIGS. 2 and 3, when viewed from the vertical direction, the shim member 46 has a U shape in which one side in the depth direction is open. . The shim member 46 is disposed between the second surface 12B of the test piece 10 and the second opposing surface 36B of the jig 32, and sandwiches the connecting portion 16 of the test piece 10 from the width direction. Furthermore, the gradient of the plate surface 46A on the second facing surface 36B side in the shim member 46 is 1/100 with respect to the opposite surface, and as shown in FIGS. 5 (A) and 5 (B), the width As viewed from the direction, it is inclined so as to come into contact with the second facing surface 36B. The shim member 46 is configured to fill a gap generated between the second surface 12B and the second facing surface 36B.

  In the present embodiment, as shown in FIG. 2, the shim member 46 has a length in the width direction (L25 in the figure) of 12 [mm] and a length in the depth direction (L26 in the figure) of 17 [mm]. The thickness is about 2 [mm].

-Heating / cooling tester 60-
The heating / cooling tester 60 is a so-called heat cycle tester, and is used to load a test piece with a temperature change between a high temperature and a low temperature and evaluate the durability of the test piece against the temperature change in a short time.

  As shown in FIGS. 8A and 8B, the heating / cooling tester 60 includes a door 64 that opens and closes the internal test tank 62, and opens the test tank 62 by operating the door 64. In this state, the jig 32 that restrains the test piece 10 is placed in the test tank 62. And the heating / cooling testing machine 60 repeats heating and cooling with respect to the jig | tool 32 which has restrained the test piece 10 in the state which operated the door 64 and closed the test tank 62. FIG.

[Thermal fatigue test method]
Next, the thermal fatigue test method will be described in comparison with the thermal fatigue test method according to the comparative embodiment. First, regarding the test piece and the thermal fatigue test apparatus used in the thermal fatigue test method according to the comparative embodiment, portions different from the test piece 10 and the thermal fatigue test apparatus 30 of the present embodiment will be mainly described.

  As shown in FIG. 12, the restraint portions 112 formed at both ends of the test piece 110 used in the thermal fatigue test method according to the comparative embodiment are in the shape of a rectangular parallelepiped extending in the vertical direction. And the restraint part 112 does not have the surface which faces the evaluation part 14 side, but has a pair of restraint surfaces 112A which face the width direction. Further, the constraining portion 112 is formed with a through hole 112B having a circular cross section penetrating in the width direction.

  The thermal fatigue test apparatus 130 used in the thermal fatigue test method according to the comparative form includes a pair of jigs 132, two bolts 140, and two nuts 146.

  The jig 132 has a long shape extending in the vertical direction, and a rectangular parallelepiped pressing portion 134 extending in the vertical direction is formed at each end of the jig 132. The pressing portion 134 has a pressing surface 134A that faces the restraining surface 112A of the restraining portion 112, and a plurality of V-shaped blades 136 are formed on the pressing surface 134A. Further, the pressing portion 134 is formed with a through hole 134B having a circular cross section penetrating in the width direction.

  The screw diameter of the bolt 140 is smaller than the hole diameter of the through hole 112B and the hole diameter of the through hole 134B.

  Then, the respective bolts 140 are sequentially inserted from one side in the width direction into the through hole 134B formed in the pressing portion 134 of one jig 132 and the through hole 112B formed in the restraining portion 112 of the test piece 110. To do. Further, each bolt 140 is inserted into a through hole 134 </ b> B formed in the pressing portion 134 of the other jig 132. Then, the nut 146 is fastened to the bolt 140 from the other side in the width direction.

  Thus, as shown in FIG. 13, the blade 136 formed on the pressing surface 134A is press-fitted into the restricting surface 112A by pressing the pressing surface 134A of the pressing portion 134 against the restricting surface 112A of the restricting portion 112. Then, when the blade 136 is press-fitted into the restraining surface 112A of the restraining portion 112, the restraining surface 112A is plastically deformed into an uneven shape. Thereby, the restraining part 112 of the test piece 110 is restrained by the jig 132.

  It is more desirable to press-fit the blade 136 into the constraining surface 112A with a compression device such as a hydraulic press. Thereby, restraint can be strengthened by making the press-fit of the blade 136 deeper. After the press-fitting, loosening of the restraint can be prevented by fixing with the bolt 140 and the nut 146.

  Next, the thermal fatigue test method of this embodiment will be described.

  First, as shown in FIG. 1, a strain gauge 92 for measuring thermal strain is attached to the evaluation unit 14 of the test piece 10. The strain gauge 92 is electrically connected to a measuring instrument (not shown).

  Then, in the state of room temperature (for example, 22 [° C.]), the test piece 10 with the strain gauge 92 attached is inserted into the space 34 of the jig 32 as shown in FIGS. .

  Further, as shown in FIGS. 3, 5 </ b> A and 5 </ b> B, a shim is formed in the gap formed between the first surface 12 </ b> A of the restraining portion 12 of the test piece 10 and the first facing surface 36 </ b> A of the jig 32. The member 40 is inserted. In addition, the shim member 46 is inserted into a gap generated between the second surface 12B of the restraining portion 12 of the test piece 10 and the second opposing surface 36B of the jig 32. Thereby, the gravity center G1 of the test piece 10 and the gravity center G2 of the jig 32 are overlapped.

  Specifically, with respect to the gap generated above and below the upper restraining portion 12, the plate surface 40A is such that the first facing surface 36A of the jig 32 and the plate surface 40A of the shim member 40 are in contact with each other. The shim member 40 facing upward is inserted into the gap from the front side in the depth direction with respect to the jig 32. Next, the shim member 46 with the plate surface 46A facing downward is placed in the depth direction with respect to the jig 32 so that the second facing surface 36B of the jig 32 and the plate surface 46A are in contact with each other. Insert in the gap.

  Further, with respect to the gap generated above and below the lower restraining portion 12, the shim member 40 is configured such that the plate surface 40A faces downward so that the first facing surface 36A of the jig 32 and the plate surface 40A are in contact with each other. Is inserted into the gap from the back side in the depth direction with respect to the jig 32. Next, the shim member 46 with the plate surface 46A facing upward so that the second facing surface 36B of the jig 32 and the plate surface 46A are in contact with each other is spaced from the front side in the depth direction with respect to the jig 32. To insert.

  By inserting the shim members 40 and 46 into the gaps, the distal ends and the base ends of the shim members 40 and 46 protrude from the jig 32, and each gap is filled. Thereby, the restraining part 12 of the test piece 10 is restrained by the jig. That is, in the thermal fatigue test method of the present embodiment, the restraint portion 12 of the test piece 10 is restrained by the jig 32 by bringing the shim members 40 and 46 into contact with the restraint portion 12 from the longitudinal direction of the test piece 10 ( Restraint process).

  Next, the test piece 10 and the jig 32 in which the restraining portion 12 is restrained by the jig 32 are placed in the test tank 62 (see FIG. 8) of the heating / cooling tester 60. And the temperature change of high temperature and low temperature is loaded to the test piece 10 and the jig | tool 32, and heating and cooling are repeated. In the present embodiment, as shown in the temperature waveform of the graph of FIG. Further, the temperature was maintained at 2 [min] or higher at a high temperature, held at 0.4 [min] or higher at a low temperature, and heating and cooling were repeated with one cycle being 6 [min].

  As a result, thermal strain caused by the difference in thermal expansion between the test piece 10 and the jig 32 is concentrated on the evaluation unit 14 of the test piece 10. In this embodiment, since the thermal expansion coefficient of the jig 32 is smaller than the thermal expansion coefficient of the test piece 10, the evaluation unit 14 is relatively vertically moved (longitudinal direction) during heating (at a high temperature). The evaluation unit 14 is relatively pulled in the vertical direction (longitudinal direction) at the time of cooling (at the time of low temperature) (stretching and restraining step).

  Here, in this embodiment, as described above, the restraint portion 12 of the test piece 10 is restrained by the jig 32 by bringing the shim members 40 and 46 into contact with the restraint portion 12 from the longitudinal direction of the test piece 10. ing.

  On the other hand, in the thermal fatigue test method of the comparative form, as described above, the blade 136 formed on the pressing surface 134A by pressing the pressing portion 134 of the jig 132 against the restraining portion 112 of the test piece 110 from the width direction. Is press-fitted into the restraining surface 112A. Then, the blade 136 is press-fitted into the restraining surface 112A of the restraining portion 112, so that the restraining surface 112A is plastically deformed into an uneven shape. Thereby, the restraining part 112 of the test piece 110 is restrained by the jig 132. That is, in the thermal fatigue test method of the comparative form, the blade 136 formed on the pressing surface 134A is press-fitted into the restraining surface 112A from the direction (width direction) orthogonal to the expansion / contraction direction (vertical direction) of the test piece 110. Thus, the test piece 110 is restrained by the jig 132.

  For this reason, in the expansion / contraction restraint step, the concave and convex concave portions of the restraint surface 112A expand in the vertical direction due to the force acting when the test piece 110 tries to expand and contract in the vertical direction. Due to the widening of the recess, the restraint of the test piece 110 was loosened during the test.

  In FIG. 11, the change of the distortion of the evaluation part 14 of the test piece 10 of this embodiment accompanying a heating and cooling cycle is shown by the graph. The horizontal axis indicates the number of heating and cooling cycles, and the vertical axis indicates the total strain range [%] that is the difference between the peak values at the end of cooling and at the end of heating in each cycle.

  When the restraint of the restraint portion 12 is loosened during the test, the total strain range is reduced. However, in this embodiment, since the total strain range is not reduced during the test, it is considered that the restraint of the restraint portion 12 is not loose. It is done. In addition, it is thought that the total strain range rapidly increased immediately before the fracture because a crack occurred in the evaluation unit 14.

(Summary)
As described above, in the present embodiment, the restraint portion 12 of the test piece 10 is restrained by the jig 32 by bringing the shim members 40 and 46 into contact with the restraint portion 12 from the longitudinal direction of the test piece 10. For this reason, compared with the thermal fatigue test method which concerns on a comparison form, it can suppress that the restraint of a test piece loosens.

  In the above-described embodiment, the gap in the vertical direction is filled by inserting the shim members 40 and 46 into the gap generated between the restraining portion 12 of the test piece 10 and the jig 32 in the vertical direction. . For this reason, even when the vertical length of the test piece 10 and the vertical length of the jig 32 vary, the restraining portion 12 of the test piece 10 can be restrained by the jig 32.

  In the restraining process of the above embodiment, the shim member 40 that fills the gap between the first surface 12A and the first facing surface 36A in the upper restraining portion 12 is replaced with the second surface 12B and the second facing surface 36B. The shim member 46 is inserted from the opposite direction to the insertion direction of the shim member 46 to be inserted into the gap. Similarly, in the lower restraining portion 12, the shim member 40 that fills the gap between the first surface 12A and the first facing surface 36A is inserted into the gap between the second surface 12B and the second facing surface 36B. The shim member 46 is inserted from a direction opposite to the insertion direction. For this reason, compared with the case where all the shim members are inserted into the gap from the same direction, the restraint portion 12 can be prevented from shifting in the insertion direction of the shim members 40 and 46 with respect to the jig 32. .

  Moreover, in the test piece 10, the restraint part 12 is made into the rectangular parallelepiped shape. For this reason, for example, when the maximum width in the width direction of the restraint portion is determined, the restraint portion has a rectangular parallelepiped shape extending in the depth direction. The area of the surface 12A and the second surface 12B can be increased. Further, for example, when the maximum length in the depth direction of the restraint portion is determined, the restraint portion is formed in a rectangular parallelepiped shape extending in the width direction. The area of 12A and the 2nd surface 12B can be expanded.

  Moreover, in the thermal fatigue test apparatus 30, compared with the case where the thermal fatigue test apparatus 130 which concerns on a comparison form is used, it can suppress that the restraint of the test piece 10 loosens during a test.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments can be taken within the scope of the present invention. This will be apparent to those skilled in the art. For example, in the above-described embodiment, a total of four shim members 40 and 46 are used. However, by bringing one surface of the restraint portion 12 into direct contact with the jig 32, a total of three shim members 40 and 46 are used. Also good.

  Moreover, in the said embodiment, although the thermal expansion coefficient of the jig | tool 32 was small compared with the thermal expansion coefficient of the test piece 10, the thermal expansion coefficient of the test piece 10 compared with the thermal expansion coefficient of the jig | tool 32. Can be small.

  Moreover, in the said embodiment, although the clearance gap which the distance varied by providing the gradient to the shim members 40 and 46 was filled, you may fill the clearance gap where the distance varied by preparing several types of shim members.

  Moreover, the material of the test piece 10 described in the above embodiment is an example, and a test piece of another material may be used.

  Further, it is desirable that the inclination directions of the gradients of the first facing surface 36A and the second facing surface 36B of the jig 32 are all parallel. In the present invention, it is important for the clearance between the jig 32 and the test piece 10 and the shim members 40 and 46 to coincide with each other in order to eliminate the clearance with high accuracy. By making the first opposing surface 36A and the second opposing surface 36B of the jig 32 parallel, it is possible to process all the surfaces simultaneously. Thereby, the gradient of the gap becomes constant and the gap can be eliminated with high accuracy.

DESCRIPTION OF SYMBOLS 10 Test piece 12 Restraint part 12A 1st surface 12B 2nd surface 14 Evaluation part 30 Thermal fatigue testing apparatus 32 Jig 36A 1st opposing surface 36B 2nd opposing surface 40 Shim member (an example of a restraining member)
46 Shim member (an example of restraint member)
60 Heating / cooling testing machine

Claims (5)

A thermal fatigue test method in which the both end portions of a long test piece having an evaluation portion having a smaller cross-sectional area than both end portions at the center portion are restrained by a jig having a different thermal expansion coefficient with respect to the test piece. There,
A restraining step of bringing a restraining member into contact with the both ends from the longitudinal direction of the test piece and restraining the both ends of the test piece with a jig;
In a state where both ends are constrained by the jig, heating and cooling are repeated, and an expansion and contraction restraining step of constraining the expansion and contraction of the test piece in the longitudinal direction,
A thermal fatigue test method comprising: A first surface facing the opposite side of the evaluation part side in the longitudinal direction and a second surface facing the evaluation part side in the longitudinal direction are respectively formed at the both ends.
The jig is formed with a first facing surface facing the first surface and a second facing surface facing the second surface,
In the restraining step, the first surface and the first facing surface are opposed to each other, the second surface and the second facing surface are opposed to each other, and the first surface and the first facing surface are between The thermal fatigue test method according to claim 1, wherein a shim member as the restraining member is inserted into a gap formed between the second surface and the second facing surface. In the both end portions, a gap is generated between the first surface and the first facing surface, and between the second surface and the second facing surface, respectively.
In the restraining step, at one end, the shim member that fills a gap formed between the first surface and the first opposing surface is generated between the second surface and the second opposing surface. The shim member is inserted from a direction opposite to the insertion direction of the shim member to be inserted into the gap, and fills the gap generated between the first surface and the first facing surface at the other end. The thermal fatigue test method according to claim 2, wherein the thermal fatigue test method is inserted from a direction opposite to an insertion direction of the shim member to be inserted into a gap formed between the second surface and the second facing surface. A long test piece used in the thermal fatigue test method according to any one of claims 1 to 3,
Formed in the central part in the longitudinal direction, and a cylindrical evaluation part;
A rectangular parallelepiped formed at both ends in the longitudinal direction, the first surface facing the side opposite to the evaluation part side in the longitudinal direction, and the second surface facing the evaluation part side in the longitudinal direction A restraint part formed with,
A test piece having A thermal fatigue test apparatus used in the thermal fatigue test method according to any one of claims 1 to 3,
In the longitudinal direction of the test piece, a first facing surface facing the first surface facing the opposite side to the evaluation part side at both ends of the test piece, and a second facing the evaluation part side at both ends of the test piece A jig formed with a second facing surface facing the surface;
A plurality of shim members that fill gaps formed between the first surface and the first facing surface and between the second surface and the second facing surface and restrain the both ends with the jig. When,
A heating and cooling tester that repeats heating and cooling in a state where both ends are constrained by a jig, and
A thermal fatigue test apparatus comprising: