JPS6338563A - Sheet having resistance to deformation at high temperature and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture a sheet having high resistance to deformation at high temp. and causing cracking in four directions when deformed in an Erichsen test by rolling an ingot in one direction until a specified draft is attained and by further rolling it to the final thickness in a direction perpendicular to the rolling direction. CONSTITUTION:When an Mo or W alloy ingot as stock for a panel heater is rolled to the final thickness at 100% draft, the stock is rolled in one direction until 76-84% draft is attained and then it is rolled to the final thickness in a direction perpendicular to the rolling direction. Thus, a sheet causing cracking 1 in four directions as shown by the figure when deformed in an Erichsen test is obtd. Since the grains of the stock are uniformly drawn in the longidudinal and lateral directions, the sheet reacts uniformly to strain and the grain boundaries have uniform strength. Accordingly, a panel heater having high resistance to deformation at high temp. is obtd.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to a method of manufacturing a high temperature deformation resistant plate material.

In particular, the present invention relates to a method for manufacturing a plate material that is resistant to high temperature deformation and that changes the grain arrangement of the plate material during rolling.

[Conventional technology] Generally, a vacuum furnace at a high temperature of 1300°C or higher.

Heaters for reducing atmosphere furnaces, inert gas furnaces, etc.
Molybdenum or tungsten, which is a high melting point material, is used, and the shape of the heater, such as a wire, rod, stranded wire, or plate, is selected in order to equalize the temperature distribution inside the furnace.

However, depending on the furnace, for a given temperature.

Some products require an accuracy of ±0.1% (for example, 1500°C ±0.15°C), and at this time, deformations such as twisting, warping, and drooping may occur while the heater is energized and heated. When this occurs, the distance between the object to be heated and the heater changes, which impairs the uniformity of temperature distribution.

[Problems to be solved by the invention] However, conventionally, molybdenum and tungsten materials, which are the materials for heating heaters, have been forged or rolled.

The plate has been subjected to plastic processing such as wire drawing and rolling, and as a result, the residual strain that occurs inside the plate is uneven.

It is unsuitable for furnaces that require highly accurate temperature distribution.

In particular, plate-shaped heaters are used in furnaces that require a soaking zone with a wide range of temperatures, unlike pond-shaped heaters, which improves their high-temperature deformation resistance. The reality is that there is a high demand for this.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, an object of the present invention is to provide a plate material with high resistance to high temperature deformation and a method for manufacturing the same.

[Means for solving the problem] According to the present invention, among the crack surfaces obtained by deforming the plate material to a value equal to or higher than the Erichsen value, the crack directionality of the crack surface exhibits four directions. High temperature deformation resistant plate material can be replaced.

Furthermore, according to the present invention, the processing rate of rolling from the ingot to the final plate thickness is 76% to 84%, and then rolling is performed in one direction.

A method for manufacturing a high temperature deformation resistant plate material is obtained, which is characterized in that rolling is carried out in a direction perpendicular to the rolling direction.

[Example] Embodiments of the present invention will be described with reference to the drawings.

First, when rolling molybdenum, tungsten, or their alloys, which are the materials for a plate heater, the processing rate from the ingot to the final thickness of the material is 100%.
%, up to the specified processing rate.

The plate material is rolled in one direction, and then re-rolled (hereinafter referred to as cross-rolling) in a direction perpendicular to the previous rolling direction.

Specifically, the thickness of the ingot is To, the final thickness is to,
When the plate thickness during cross-rolling is tx.

Cross rolling is performed within the thickness range shown by the following formula.

tx=ETo+(1-E) to...(a) However,
0.1G≦E≦0.24 For example, tx at 60% machining rate from To to to.

tx=0.4(To-to)+t.

=0.4To+0.8to...(b)

Next, tx at 40-60% machining from tx to to.

tx=0.40~0. H (tx -to) ten to...
-Represented by (c).

Here, if we substitute equation (b) into equation (C).

tx=0.4 ~O, GE (0,4TO+0.6tO)
-Toko +t.

=0.4-0.6(0,4To-0,4to)+t.

=E (To-to)+t.

=ETo+(1-E)t.

becomes.

Next, among the crack surfaces obtained by deforming the plate material to a value higher than the Erichsen value of the plate material, the crack directionality of the crack surface is measured,
Based on the crack directionality, a high temperature deformation resistance test was conducted to test the high temperature deformation resistance of the plate material.

As shown in Table 1, samples of different thicknesses (30 mm, 2θam, 101 mm) obtained by the known powder metallurgy method
) Three types of molybdenum ingots, hot and warm.

Repeated cold rolling and intermediate annealing.

When rolling each ingot, plate materials Ab and B are rolled with cross rolls defined by the E value according to the present invention.
b, Cb, plate material Ac + Bc + Cc rolled with cross rolls other than E value, and plate material A a + B rolled in one direction (hereinafter referred to as straight roll)
Divide into b + Cc and pressurize to the final finished thickness.

Next, as shown in Figure 1, each rolled plate material is
An indenter ball for Erichsen test is extruded 3 mm deeper than the Erichsen value of JIS B7729 to obtain 1 crack surface 1.

As shown in Figure 2, the crack directionality of the crack surface obtained from each plate shown in Table 1 is as follows for Ab, Bb, and Cb plates:
It has four directions; other plates have two or three directions. That is, Ab and Bb are subjected to a cross roll defined by the E value.

This is because in the cb plate, the crystal grains of the rolled plate are uniformly stretched vertically and horizontally, so they react uniformly to strain, and the strength of the grain boundaries is uniform.

Next, as shown in FIG. 3, each plate shown in Table 1 was cut into a plate shape of 20 mm width x 20 Q mm length using another high temperature deformation resistance test method, and installed as heater material 2 in vacuum furnace 3. , vacuum degree I x 10 Torr, heating temperature 17
The heating conditions were 00 degrees Celsius and a holding time of 10 hours. Thereafter, the cooled molybdenum plate 2 was taken out, and its maximum deformation amount was determined as shown in FIG.

It was measured. The results are shown in Table 2.

Table-1 The following is a clue table-2 [Invention Effect] According to the present invention, by rolling with cross rolls defined by the E value, it is possible to provide a plate material with high high temperature deformation resistance and a method for manufacturing the same. .

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a plate material cracked according to an embodiment of the present invention, Fig. 2 is a schematic diagram without showing the crack direction of the crack surface according to an embodiment of the present invention, and Fig. 3 is a conventional A schematic diagram of the high temperature deformability test method, FIG. 4 is a schematic diagram of the method of measuring the maximum amount of deformation. 1... Cracked surface, 2... Molybdenum plate, 3... Vacuum furnace. Agent (7783) Patent Attorney Noriyasu Ikeda Figure 1 Figure 2-1111-aS Winter Roll Direction

Claims (1)

[Scope of Claims] 1) A high-temperature deformation-resistant plate material, characterized in that among the crack surfaces obtained by deforming the plate material to a value greater than the Erichsen value, the crack directions of the crack surfaces exhibit four directions. 2) The processing rate of rolling from the ingot to the final plate thickness, the processing rate of 76 to 84% is rolling in one direction,
A method for manufacturing a high temperature deformation resistant plate material, which is then rolled in a direction perpendicular to the rolling direction.