JP2702631B2 - Hearth opening cover support members - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member for supporting a hearth opening cover, and more particularly, to a movable beam post of a walking beam type transfer mechanism for transferring a material to be heated in a heating furnace. The present invention relates to a hearth opening cover supporting member attached to a post portion of the moving beam so as to support a cover for shielding a hearth opening to be inserted from the inside of the furnace.

[0002]

2. Description of the Related Art A heating furnace provided with a walking beam type transfer mechanism is used, for example, to heat or keep a material to be heated such as a slab in a stage before a hot rolling step following a continuous casting step. . The hearth of the heating furnace is provided with a hearth opening through which the post portion of the moving beam of the walking beam type transfer mechanism is movably inserted. At the hearth opening, the post part is installed laterally.
The hearth opening cover supporting member (hereinafter, referred to as a cover supporting member) formed of a stick-like body attached thereto is locked and supported.
The covered cover shields the inside of the furnace, so that heat loss in the furnace is suppressed as much as possible. Conventionally, as the cover supporting member, a member made of a heat-resistant Co-Cr-Ni-based cast steel has been mainly used so as to withstand use in the heating furnace. In addition, Cr in the heat-resistant cast steel
The content is set under conditions (for example, Cr: 28% or less) to avoid a region where a fragile σ phase appears in the alloy phase diagram on the low Cr side.

[0003]

In recent years, the heating furnace has been
A high temperature exceeding 1300 degrees Celsius (for example, 13 degrees Celsius)
(50 ° C.), the cover supporting member made of the heat-resistant cast steel has a problem that it cannot withstand use under the high-temperature operating conditions. That is, the cover supporting member is provided on the post portion in a lateral direction.
Because it consists of a rod attached to the
Receive the load of the locking and supporting cover as a cantilever
Moreover, the cooling effect from the post part is
When exposed to the high-temperature operating conditions, creep deformation occurs even though it is made of the heat-resistant cast steel.
Therefore, there is a problem that it cannot withstand long-term use . Therefore, in order to solve the above-mentioned problem, deformation, melting, oxidative damage, and the like do not occur even under the high-temperature operating conditions.
Although a cover supporting member made of ceramics such as iC is also used, the cover supporting member made of ceramics is liable to crack or break due to thermal shock. There is a problem that it cannot withstand use under high-temperature operating conditions. The present invention has been made in view of such circumstances, and avoids the occurrence of deformation, erosion, oxidative damage, and the like under the high-temperature operating conditions, and has a thermal shock under the high-temperature operating conditions. It is an object of the present invention to provide a cover supporting member capable of avoiding the occurrence of cracks, breakage, and the like due to cracks and thereby enduring use under the high-temperature operating conditions.

[0004]

A hearth opening cover supporting member according to the present invention is a hearth opening cover supporting member according to the first aspect, wherein the rod-like member is made of 75 to 90% by weight of chromium,
The first characteristic configuration is that the balance is formed of a chromium-based alloy substantially composed of iron .

Further, 1 to 3% by weight of tantalum and 1 to 3% by weight
One or two elements of the weight percent of molybdenum, the total triple
If it (i.e. containing less amount%, while containing 75-90% by weight of chromium, the total of 3 wt% or less, 1
3% by weight of tantalum and 1-3 wt% of one or molybdenum, contain, and the balance substantially that of iron) as the second characterizing feature.

[0006]

The cover supporting member having the first characteristic configuration is:
High temperature properties such as deformation resistance, erosion resistance and oxidation resistance at high temperatures
The chromium content of the provided chromium-based alloy is 75-90% by weight
As the remainder is iron , unlike the conventional heat-resistant cast steel, it is possible to avoid the occurrence of the creep deformation , melting damage, oxidation damage, and the like even when exposed to the high-temperature operating conditions.
You . Further, the cover supporting member has a chromium content ,
Since it is 75% by weight or more, while the rest is iron,
In the alloy phase diagram, deviate from the region where the fragile σ phase appears .
In addition , while having excellent high-temperature characteristics as described above, it prevents embrittlement under the high-temperature operating conditions, and is excellent not only in crack resistance but also in creep resistance .
Accordingly, the cover supporting member, it so different from those made of ceramics such as SiC, generation of cracks and breakage due to thermal shock under the conditions of operation the high temperatures are avoided
In addition, it is hard to cause creep deformation . In other words,
By using a chromium-based iron alloy with excellent creep properties
Therefore, the durability of the cover supporting member is improved.
It is. The reason why the chromium content is suppressed to 90% by weight or less is that if the chromium content exceeds 90% by weight, the creep resistance under the above-mentioned high-temperature operating conditions decreases.
You .

The cover supporting member having the second characteristic configuration is made of a material containing an appropriate amount of tantalum or molybdenum as an alloy element for particularly improving the deformation resistance, and therefore, under the above-mentioned high-temperature operating conditions. Is further improved in creep deformation resistance . In other words, either tantalum or molybdenum
Content, or the total content of both, to 3% by weight or less.
The properties of chromium-based iron alloys are substantially maintained.
It is done.

[0008]

Therefore, the cover supporting member having the first characteristic configuration can avoid the occurrence of creep deformation, melting damage, oxidation damage, and the like under the high-temperature operating conditions, and can avoid the occurrence of the high-temperature operating conditions. look like cracks or damage due to thermal shock under is avoided, with it, it is possible to impart durability against the use under conditions of operating the hot.

Further, in addition to the above-described effects, the cover supporting member having the second characteristic configuration can more reliably prevent deformation under the high-temperature operating conditions, and can prevent creep resistance under the high-temperature operating conditions. sex is further improved, more durable for use
Will be able to give sex .

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show a main part of a heating furnace (a cover supporting member according to the present invention) used for heating or keeping a material to be heated as a pretreatment of a hot rolling step subsequent to a continuous casting step. FIG. 3 shows an outlet portion of the heating furnace.

S in FIG. 3 is a slab as the material to be heated, which is obtained by cutting a continuous cast material cast in a continuous casting step into an appropriate length. The slab S is provided in the heating furnace. The heating beam is conveyed in the heating furnace by the walking beam type conveyance mechanism, and is heated or kept at a temperature suitable for the hot rolling step in the course of the conveyance.

The above-mentioned walking beam type transport mechanism comprises a fixed beam 1 and a moving beam 2 (both beams are formed into a substantially inverted U-shape by joining pipe members, and the post portions 1a,
2a and horizontal portions 1b and 2b).
Are arranged alternately in the furnace width direction in the heating furnace, with the longitudinal direction along the conveying direction of the material to be heated (see FIG. 4).

The fixed beam 1 has a post portion 1a.
Is mounted on the hearth 3 of the heating furnace in a fixed state, and a large number of skid buttons 4 carrying the slab S are mounted on the horizontal portion 1b. A post portion 2a of the moving beam 2 is movably inserted into a hearth opening 3a opened in the hearth 3, and a large number of skid buttons 4 carrying the slab S are provided on a horizontal portion 2b thereof. Pieces are attached. The moving beam 2 has its post portion 2a repeatedly driven by a driving mechanism (not shown) in the order of ascending, advancing, descending, and reversing. Based on the repetitive driving, the horizontal portions 1b, The slab S placed on the 2b via the skid button 4 is gradually transported forward.

If the hearth opening 3a opened in the hearth 3 is left unshielded, heat in the furnace is released from the hearth opening 3a, causing a large heat loss. Therefore, a cover 5 is provided above the hearth opening 3a to suppress heat release in the furnace by shielding. The cover 5 is provided on the post part 2 of the moving beam 2.
The supporting member 6 is supported by the cover supporting member 6 according to the present invention mounted on a.

The cover 5 includes the cover supporting member 6.
Are formed by combining a large number of plate-shaped ceramic fiber boards 5a each having an insertion hole through which the hole is inserted. Then, the ceramic fiber boards 5a are fixed to the post portions 2a of the moving beam 2 by being fixed to the post portions 2a of the moving beam 2 by inserting the cover support members 6 into the respective insertion holes and fixing the ceramic support boards 6 in a close contact state. Is locked through.

As shown in FIGS. 1 and 2, the cover supporting member 6 is provided in the direction of conveyance of the material to be heated, directly or via a mounting member with respect to the post portion 2a of the moving beam 2. And a round bar attached in a posture extending in the opposite direction. As the material, a heat-resistant alloy containing 75 to 90% by weight of Cr and substantially consisting of Fe is used. In addition, Cr: 75 to 90% by weight% and Ta: 1 to 1
It is more preferable to use a heat-resistant alloy containing 3% and Mo: 1 to 3% of one or two elements, that is, a total of 3% or less and the balance substantially consisting of Fe. Such a heat-resistant alloy can be manufactured by various manufacturing methods that avoid contact with the atmosphere during the manufacturing process in order to suppress impurities such as nitrogen (nitrogen causes fragile chromium nitride) during the manufacturing process, for example, a hot isostatic sintering method. (HIP
), Cold isostatic sintering (CIP), vacuum melting, and vacuum casting.

The cover supporting member 6 is made of chromium having high temperature characteristics such as deformation resistance, erosion resistance and oxidation resistance at high temperatures.
The Cr content of the base alloy is 75 to 90% by weight , and the balance is
Since Fe is used , creep deformation, melting damage, oxidation damage, and the like can be avoided even under conditions where the furnace is operated at a high temperature (for example, 1350 degrees Celsius) where the temperature in the furnace exceeds 1300 degrees Celsius. Moreover, the cover supporting member 6 is
Since the Cr content is set to a condition that avoids the region where the fragile σ phase appears on the high Cr side, it has excellent high-temperature characteristics as described above, but also has crack resistance under the high-temperature operating conditions. In addition, cracking and breakage due to thermal shock under the high-temperature operating conditions can be avoided. Furthermore,
When the cover supporting member 6 is made of a material containing an appropriate amount of Ta or Mo as an alloy element for particularly improving the deformation resistance, the deformation resistance of the member 6 under the high-temperature operating conditions is further improved. Is done.

Next, with respect to the high-temperature characteristics (deformation resistance) of the material of the cover supporting member 6, a conventional material (heat-resistant cast steel) was used.
The result of comparison with will be described. Table 1 is a list of the comparison results described above.

[0019]

[Table 1]

In the table, the contents of the alloying elements are shown by weight%. Deformation resistance is 1350 degrees Celsius for the sample.
4.9 N / mm ² load (compression load) in an atmosphere of 1 degree
It is shown as the amount of creep deformation (%) that occurs over time. Sample Nos. 1 to 7 correspond to Examples of the present invention, and Sample Nos. 11 and 12 correspond to Comparative Examples in which the conditions of the present invention were deviated.
When the content exceeds 90%, sample No. 12 has a Cr content of 7
Sample number 13 corresponds to a conventional example (heat-resistant cast steel). Sample No. 3 to Sample No. 7
Contains an appropriate amount of Ta or Mo as an alloy element for particularly improving deformation resistance. From Table 1, it can be seen that the examples of the present invention have better deformation resistance than the conventional examples. It is also found that those containing an appropriate amount of Ta or Mo have further improved deformation resistance.

Next, another embodiment will be described. The member for supporting a hearth opening cover according to the present invention can be applied to a heating furnace other than the above-described embodiment in which a material to be processed other than the slab is heated while being conveyed by a walking beam type conveyance mechanism. Needless to say.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an installation portion of a cover supporting member according to the present invention.

FIG. 2 is a plan view thereof.

FIG. 3 is a longitudinal sectional view showing a heating furnace provided with a walking beam type transport mechanism.

FIG. 4 is a sectional view showing a walking beam type transport mechanism.

[Explanation of symbols]

 2 Moving beam 2a Post part 3a Hearth opening 5 Cover

Claims (2)

(57) [Claims] A hearth opening (3a) through which a post (2a) of a moving beam (2) of a walking beam type transport mechanism for transporting a material to be heated in a heating furnace is movably inserted.
Consisting refractory to perform shielding from the furnace inner side against the cover (5), in order to lock the support, said post portion (2a)
A hearth opening cover supporting member constituted by a rod-shaped body (6) attached to a lateral direction, wherein the rod-shaped body (6) is composed of 75 to 90% by weight of chromium and the balance A member for supporting a hearth opening cover formed of a chromium-based alloy substantially consisting of iron . 2. The method according to claim 1, wherein said chromium-based alloy has a
Element or molybdenum of 1% by weight or more
Is the content of any one of the above elements,
The member for supporting a hearth opening cover according to claim 1 , wherein the total content of the two elements is 3% by weight or less .