JPS59173220A - Heat treatment of metallic bar material having different wall thickness - Google Patents

Abstract

PURPOSE:To uniformly heat-treat the whole body of steel pipe without irregularity, by a method wherein in heat-treating the heavy steel pipe having thick wall parts at both ends, annular inductors of different diameters are respectively arranged at the thick wall part and the intermediate regular part, and the induction heating and the successive heat-treatment by water cooling are carried out moving said annular conductors. CONSTITUTION:In heat-treating the heavy steel pipe having thick wall parts 1a and 1b at both end parts and consisting of a regular part 1 through its intermediate part, annular conductors 2 and 4 having water cooling jackets 2a and 4a are respectively arranged at both end parts 1a and 1b and the annular conductor 3 having water cooling jacket parts 3a and 31a through the regular part 1c, too. After heating the thick wall part 1a to a fixed temperature by applying power to the conductor 2 at first, the conductor is raised supplying the power compensating for the cooling of heat part by radiation convection and the heat-treatment is carried out by cooling the wall spraying water from the nozzle 2b of jacket 2a. Successively the regular part 1c and the thick wall part 4 are heat-treated by spraying water from respective conductors 3 and 4 and water cooling jackets 3a, 31a and 4a, and the toughness is raised by uniformly heat- treating the entire body of steel pipe 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently and uniformly heat treating metal strips having different wall thicknesses, particularly large ones with large thickness differences.

Gold FfG'M has recently been used for ocean development, etc. Structures are often destroyed by wind and waves due to their large size and the harsh natural environment in which they are installed.

Conventionally, from the viewpoint that it is necessary to increase the strength of the above-mentioned structure in order to prevent such destruction, a copper phase with a high tensile strength thickness has been used as a structural material. It is believed that accidents such as collapse of structures occur because there are problems with the low-temperature toughness, weldability, etc. of the above-mentioned structural materials.

Therefore, in order to construct a t+W structure with sufficient strength and excellent toughness, it is necessary to increase the toughness of the structural material by tempering the structure or shape of the structural material to a certain extent, and also to simplify the strength of this structural material. It is also desirable to use threaded joints to avoid welding, which can easily expose defects. Considering this point when steel pipes are used as structural materials, it is necessary to form thick-walled parts at the ends of the steel pipes for threaded joints, and to increase the toughness of steel pipes with different wall thicknesses, it is necessary to This means that uniform heat treatment must be applied to the entire surface.

However, since the steel pipes shown in -[- are used as structural materials, their overall wall thickness is large, and the pipe ends formed into threaded joints are formed to be about three times as thick as other parts. Because of this, the difference in wall thickness is also large (but the overall shape has a diameter of 50cm).
It ranges from about m to several meters, and even has a length of at least 12 m.
2, and weighs at least 7 or 8 tons, depending on conventionally known general heat treatment methods and equipment.
- Fact 1 - It is impossible to efficiently and uniformly heat treat steel pipes as described above.

The present invention is applicable to a metal strip such as a steel pipe, which has a large overall wall thickness, and the thick wall portions formed at the ends are thicker with a larger difference in wall thickness. This was developed with the aim of providing a method that can perform heat treatment efficiently and uniformly, and its structure consists of vertically connecting metal strips with different wall thicknesses, with both ends being thicker than the stationary part. Or, place it in a horizontal position and place it in a horizontal position.
An annular inductor is placed on the starting end side of different parts of the strip, and by moving the inductor in the longitudinal direction of the strip, the strip is continuously heated and the heated portion is heated. In the heat treatment in which cooling water is continuously supplied, the -
The thick part of the ・ side is heated to a predetermined temperature of 43 degrees with the entire thick part surrounded by a 1A inductor for the thick part, and then the radiation convection loss of the part heated by the inductor ・ is heated. Supply electric power to compensate for the inductor and move the inductor to the rear end side or to the boundary with the stationary part or the vicinity thereof.In synchronization with this movement, 1) Applying heat treatment to the thick wall portion described in item 11 by supplying cooling water to At the same time, the inductor is not moved toward the other end of the stationary section, and in synchronization with the movement, cooling water is continuously supplied to the section heated by the inductor. In some cases, the steady region is continuously heat-treated, while the entire thick-walled part is heated in the time required to reach the end of the steady-state part from the nh inductor in the middle of the heat treatment of the steady-state part. Power is supplied to the other thick part inductor to start heating the thick part so as to match the time required for heating to a predetermined temperature by the 1A conductor for the steady part, and the steady part inductor starts heating the thick part. When the inductor for the stationary section reaches the end of the stationary section or its vicinity, the power supply to the inductor for the stationary section is stopped. While supplying sufficient power to compensate for convection losses, the inductor is moved from the boundary side of the stationary part to the other end, and in synchronization with this movement, cooling water is continuously supplied to the part heated by the inductor. It is characterized by supplying.

Next, embodiments of the present invention will be described with reference to the drawings.

In order to form threaded joints at both ends, 1 is a steel pipe serving as a structural member in which these parts are formed into thick walled parts 1a and Ib, and IC is a stationary part between the two thick walled parts.

On the other hand, the steel pipe 1 has, for example, a nominal diameter of 500 m, a total length of 12 m, a wall thickness of the stationary part IC of 25n*n, and a wall thickness of the thick walled parts 1a and lb at both ends of 75 mm. Although there are pipes in which the length of the section is 700 strokes, the metal strip to which the present invention can be applied is, of course, not limited to the above-mentioned steel pipe. Incidentally, the structure shown in FIG. 1 is different in the form of the thick portions Ia and Ib.

2 is an inductor for the thick section 1a of the steel pipe 1, and 3 is the steady section 1.
4 is an inductor for the thick wall portion 1b; in this case, since the shapes of the γ interiors 1a and lb are different, the inductors for the thick wall portion may be different or different. , thick wall portion 1a, ]
, b have the same form, one thick-walled inductor is sufficient. FIG. 2 shows an example of this case.

Therefore, the inductors 2 and 4 for the thick parts have thick walls la and l, respectively.
A cooling water jacket 2 has a wide band shape that covers the entire area b, and has nozzles 2b and 4b for spouting cooling water at its lower end.
A and 4a are provided.

Further, the inductor 3 for the steady section is narrower than the above-mentioned inductor J'2.4, and has two types of cooling water jet nozzles 3b and 31b as shown in FIG.
], a.

The above-mentioned inductors 2 to 4 are set in the state shown in FIG. 1 with respect to a steel pipe fixed in a vertical direction for carrying out the method of the present invention, and are shown in FIGS. 5 to 10. -Depending on the process, steel pipe l
Continuously heat-treated. .

First, as shown in Figure 5, with the Ω element 3 in place,
Electric power is supplied to the knob to start heating the inside 1a of the knob, and the diameter portion 18 is heated in a stationary state until it reaches a predetermined temperature, for example, 100°C. At this time, the other guides r3 and r4 are not activated. The opening in the figure is the heated part.

When the thick part 1d is heated to a predetermined temperature, the induction T-2
At the same time, the inductor 2 begins to move in the L direction, and -), the inductor 1-2a Nozzle 2b or 1. Spray cold chisel 11 water (2 2) (see Figure 6).

'', the thick wall portion 1a is successively heat-treated in the direction from the bottom to the bottom. Since there is no descent, homogeneous heat treatment of the thick portion 1a can be achieved. Note that C in the figure is a portion that has been cooled after heating.

When the inductor 2 continues to move upward and the entire area of the part I heated by the inductor 2 is heat-treated, power is supplied to the inductor 2 and cooling water is spouted at the same time as 11: Mero. An inductor 3 for the stationary section is set at the lower end of the stationary section 1c.
Electric power is supplied to the inductor, the inductor 3 starts to operate, and the stationary part 1c is heat-treated by the inductor 3 (see FIG. 7). Furthermore, L
When the thick inner part 1b of the other side has the same shape as the already heat-treated thick part 18, the inductor 2 for the thick part is further moved upward u4.
The heat treatment of the steady part C is performed by setting the heat treatment in the part of the thick part 1b of the inductor 3.
: Cooling water C3 or Jakeno 1-3a, nozzle 3 along with movement.
When the inductor 3 reaches a predetermined position in the stationary part 1c, the inductor 4 set in the upper thick part 1b collapses continuously by being ejected from the core part 1b. (See Figure 8).

That is, the predetermined position is the stationary part] c From an appropriate position during the movement of the heating inductor 3 to the end of the stationary part 1c! It is determined that the time required to reach this temperature and the time required to heat the upper thick part 1b to a predetermined temperature, for example, 900°C by the inductor 4, match, and 5-Vl, (S: For stationary part 1
Induction j' 3 (7) 452 'J movement 1 FIJ distance mm, ■: moving speed of the inductor 3 + um/sec,
t: It is determined from the equation of 11JI (5eC) required to heat the thick portion 1b to a predetermined temperature.

Then, when the thick portion 1b on the opposite side begins to be heated by the stationary heating of the induction 71'-4 and is heated to a predetermined temperature, for example, 900°C, the inductor 3 for the steady portion]C is heated to the diameter portion 1c. Reach the first end. Here, the steady portion 1c is a nozzle 3b of a cooling water jacket 3a disposed below the inductor 3.
Since the inductor 3 is cooled by the cooling water C3 ejected from the inductor 3, when the 71 inductor 3 reaches Ft to the point where it cannot move further by 1-Vj, it becomes possible to cool the area immediately below the inductor. Therefore, the salmon l provided in the upper half of the inductor 3-
, 3121 and the cooling water C3 is passed through the nozzle 31b.
1 is spouted out to cool the upper end of the stationary portion 1c (see FIG. 9).

On the other hand, when the heat treatment of the entire area of the stationary part 1c is completed as described in J-, the inductor 4 that was subsequently heating the upper thick part 1b compensates for the radiation convection loss of heat. The nozzle 1 of the cooling water jacket 4a begins to move upward at the same time as the heating output of the
Cooling water is ejected from 1b, and the thick interior 1b is continuously heat-treated (see Fig. 10).

In this way, metal strips such as pipes with different wall thicknesses can be continuously heat treated, but the method of the present invention is suitable for treating large objects with large differences in wall thickness. This method is unique in that it is possible to heat-treat a uniform crystalline layer with good effect even if there is a heat treatment, which is not possible with the conventional method.

That is, in the present invention, a plurality of induction r's corresponding to the wall thickness are used, and after heating including preheating is applied to the inside of the thick wall, the heating output of the inductor is controlled by the radiation convection of the heat of the heated part. After reducing the amount to a level that compensates for the loss, we start moving it, and the heated part is cooled and heat treated continuously.
There is almost no uneven heat treatment in the heat treatment of the thick part, and the steady part following the thick part is treated with a dedicated induction r.
・By continuously applying effective heating and cooling,
For other thick parts following this steady part, heating is started in the middle of the process of the steady part using an inductor for jq, and immediately after the heat treatment of the steady part is completed, the inductor is moved. This is because cooling is performed at the same time as the heat treatment is started, so that even though a plurality of inductors are used, strips of different thickness can be subjected to continuous heat treatment without uneven treatment.

It is theoretically possible to heat strips with different wall thicknesses with a single inductor, but if the strips are all made of dolls and there is a large difference in wall thickness, it is possible to heat strips with extremely large thicknesses. This method not only requires a power supply device, is extremely expensive, and lacks practicality, but also has drawbacks such as poor heating efficiency due to the large difference in wall thickness.

In the present invention, since the object to be treated is an εm tube with a large wall thickness, if sufficient heat treatment effect cannot be obtained by external heating alone, a heat treatment tube is installed inside the steel tube 1 for internal heat treatment as shown in Fig. 3. Inductor 5 equipped with a cooling jacket h, 5.1
may be operated in synchronization with the heat treatment operation described in the previous embodiment.

In this case, the guide 1'3 for the constant part JC is the core part 1.
When the cooling water C31 reaches the second end of the cooling water jacket h31a, the inductor 5 on the inner surface of the
The cooling water c5 is spouted from the nozzle 5b while the guide 7-
Only the portion corresponding to 3 is quickly moved ■θ to synchronize with the movement of the inductor 4 for the thick portion 1b.

This is to prevent a difference in cooling time from occurring between the inner and outer surfaces of the steel pipe.

The present invention is as follows: In particular, a metal strip such as a steel pipe, which is a doll as a whole and has a large difference in wall thickness, is provided with a plurality of heating inductors and a cooling inductor. This method is extremely useful as a heat treatment method for structural materials of individual prostheses because it can be heat-treated continuously and efficiently and uniformly using a water supply means.

[Brief explanation of the drawing]

Fig. 1 is a front view taken in cross section at section 1, showing the method of the present invention being carried out; j is a partially enlarged sectional view of the steady-state heating guide P, and FIGS. 5 to 10 are goni diagrams of examples of the method of the present invention. 1 Steel pipe, Ia, lb Thick walled part, I[: Steady part, 2
~5 Inductor, 2 a-5a, 31 a-cooling water jacket 1-12b ~ 5b, 31h cooling water jet nozzle,
Agent Yoshikawa Koizumi Figure 1 Figure 2 Figure 3 Figure 1/ Figure 5 Figure 6 Figure 7 281 Figure 9 Lena Figure 10 Figure 119

Claims (1)

[Claims] 1 Metal strips with different wall thicknesses with both ends thicker than the stationary part are placed vertically or horizontally, and annular inductors are placed at the starting ends of the parts with different wall thicknesses. While continuously heating the strip by piping and moving the inductor in the longitudinal direction of the strip,
During the heat treatment in which cooling water is continuously supplied to heated ij; The 3A inductor is heated to the rear end side or at or near the boundary with the stationary part by supplying power to the inductor to compensate for radiation convection loss in the heated part. Heat treatment is applied to the thick wall portion by continuously supplying cooling water to the heated portion in synchronization with this movement, and following this treatment, the thick wall portion is heated. Then, when power is supplied to the inductor for the stationary section placed at the starting end of the stationary section and heating of the stationary section begins, j While continuously heat-treating the stationary part by continuously supplying cooling water to the part heated by the induction=r in synchronization with the movement, 1
) The time required to reach the end of the steady part from the above induction °r during the heat treatment of the steady part described in 1f and the entire other thick wall group to the induction J' for the thick wall part until the specified temperature is reached. Power is supplied to the other thick-walled inductor to start heating the thick-walled portion so that the time required to heat the thick-walled portion coincides with the time required for heating the thick-walled portion. When reaching the part or the vicinity thereof, identification 9: (') Stops the power supply to the inductor for the part, and supplies the inductor for the other thick part to compensate for the radiation convection loss of the heated part. The inductor is moved from the boundary side of the stationary part to the other end side while supplying sufficient electric power, and in synchronization with this movement, cooling water is continuously supplied to the part heated by the inductor. A method for heat treating metal strips with different wall thicknesses.