阅读说明：本技术 一种改善钢结构焊接处应力集中的处理方法 (Treatment method for improving stress concentration of steel structure welding part ) 是由 张俊宝 于 2020-12-21 设计创作，主要内容包括：本发明公开了一种改善钢结构焊接处应力集中的处理方法；涉及钢结构技术领域,包括以下步骤：(1)对钢结构件进行清洗、去油、干燥处理；(2)将钢结构件进行焊接连接到一起；(3)对钢材焊缝进行低温热处理,得到低温热处理件；(4)对低温热处理件的焊缝处进行波段式超声波处理；本发明方法处理后的钢材焊缝处的残余应力大幅度降低,通过大幅度降低焊缝处的残余应力,能够极大的改善其应力集中的问题,进而提高其耐疲劳性能。(The invention discloses a processing method for improving stress concentration at a welding part of a steel structure; relates to the technical field of steel structures, and comprises the following steps: (1) cleaning, deoiling and drying the steel structural part; (2) welding and connecting the steel structural members together; (3) carrying out low-temperature heat treatment on the steel welding seam to obtain a low-temperature heat treatment piece; (4) performing wave-section ultrasonic treatment on the welding seam of the low-temperature heat treatment piece; the residual stress at the welding seam of the steel processed by the method is greatly reduced, and the problem of stress concentration can be greatly improved by greatly reducing the residual stress at the welding seam, so that the fatigue resistance of the steel is improved.)

1. A treatment method for improving stress concentration at a steel structure welding position is characterized by comprising the following steps:

(1) cleaning, deoiling and drying the steel structural part;

(2) welding and connecting the steel structural members together;

(3) carrying out low-temperature heat treatment on the steel welding seam to obtain a low-temperature heat treatment piece;

(4) and performing wave-section ultrasonic treatment on the welding seam of the low-temperature heat treatment piece.

2. The treatment method for improving the stress concentration of the steel structure welding position according to claim 1, is characterized in that: and the steel structural part is soaked and cleaned by sequentially adopting hot alkaline solution and acetone for cleaning and deoiling.

3. The treatment method for improving the stress concentration of the steel structure welding position according to claim 2, is characterized in that: the hot alkali solution is soaked and cleaned for 20-30min at the temperature of 80-90 ℃;

the hot alkali solution is a sodium hydroxide solution with the mass fraction of 10%.

4. The treatment method for improving the stress concentration of the steel structure welding position according to claim 2, is characterized in that: the acetone soaking and cleaning time is 10-15min, and the temperature is 50-55 ℃.

5. The treatment method for improving the stress concentration of the steel structure welding position according to claim 1, is characterized in that: and the welding is carried out in a plasma arc welding mode.

6. The treatment method for improving the stress concentration of the steel structure welding position according to claim 1, is characterized in that: the plasma arc welding speed is 200-.

7. The treatment method for improving the stress concentration of the steel structure welding position according to claim 1, is characterized in that: the low-temperature heat treatment comprises the following steps: under the protection of inert atmosphere, heating to 445-468 ℃, preserving heat for 2-3 hours, and then cooling to room temperature along with the furnace.

8. The treatment method for improving the stress concentration of the steel structure welding position according to claim 7, is characterized in that: the inert atmosphere is a nitrogen atmosphere.

9. The treatment method for improving the stress concentration of the steel structure welding position according to claim 1, is characterized in that: the wave band type ultrasonic treatment is carried out by three times: the first ultrasonic treatment time is 10-14min, the ultrasonic frequency is 25kHz, the second ultrasonic treatment time is 3-5min, the ultrasonic frequency is 40kHz, the third ultrasonic treatment time is 8-10min, and the ultrasonic frequency is 30 kHz.

Technical Field

The invention belongs to the technical field of magnetic materials, and particularly relates to a treatment method for improving stress concentration at a steel structure welding position.

Background

The steel structure factory building refers to a factory building with main bearing parts made of steel, and the factory building comprises steel columns, steel beams, a steel structure foundation, steel roof trusses and steel roof roofs. As the steel quantity in China is increased, steel structure plants are mostly adopted, and particularly, the steel structure plants can be divided into light steel structure plants and heavy steel structure plants. Industrial and civil building facilities built by steel are called steel structure plants, the steel structure plants have the advantages of light building weight, large strength and span, short construction period of the steel structure buildings, correspondingly reduced investment cost, high fire resistance of the steel structure buildings, strong corrosion resistance, convenient movement of the steel structure buildings, no pollution in recycling and the like, and are increasingly applied to plant construction.

When steel in the steel structure factory building is connected, need carry out welded connection, however, welded seam department can produce a large amount of stress concentration after the welding, causes fatigue fracture easily.

Disclosure of Invention

The invention aims to provide a treatment method for improving stress concentration at a steel structure welding part so as to overcome the defects in the prior art.

The technical scheme adopted by the invention is as follows:

a treatment method for improving stress concentration of a steel structure welding part comprises the following steps:

(1) cleaning, deoiling and drying the steel structural part;

(2) welding and connecting the steel structural members together;

(3) carrying out low-temperature heat treatment on the steel welding seam to obtain a low-temperature heat treatment piece;

(4) and performing wave-section ultrasonic treatment on the welding seam of the low-temperature heat treatment piece.

And the steel structural part is soaked and cleaned by sequentially adopting hot alkaline solution and acetone for cleaning and deoiling.

The hot alkali solution is soaked and cleaned for 20-30min at the temperature of 80-90 ℃;

the hot alkali solution is a sodium hydroxide solution with the mass fraction of 10%.

The acetone soaking and cleaning time is 10-15min, and the temperature is 50-55 ℃.

And the welding is carried out in a plasma arc welding mode.

The plasma arc welding speed is 200-.

The low-temperature heat treatment comprises the following steps: under the protection of inert atmosphere, heating to 445-468 ℃, preserving heat for 2-3 hours, and then cooling to room temperature along with the furnace.

The inert atmosphere is a nitrogen atmosphere.

The wave band type ultrasonic treatment is carried out by three times: the first ultrasonic treatment time is 10-14min, the ultrasonic frequency is 25kHz, the second ultrasonic treatment time is 3-5min, the ultrasonic frequency is 40kHz, the third ultrasonic treatment time is 8-10min, and the ultrasonic frequency is 30 kHz.

The invention can effectively reduce the defects by carrying out low-temperature heat treatment on the steel, promote uniform heating, and then carry out ultrasonic treatment in a wave section mode, can effectively improve the microstructure, and can refine weld microstructure grains, so that obvious plastic slip can occur firstly under the action of fatigue tension-compression alternating load, a better plastic deformation layer is formed, the process of generating fatigue cracks is greatly delayed, and the fatigue resistance is improved.

Has the advantages that:

the residual stress at the welding seam of the steel processed by the method is greatly reduced, and the problem of stress concentration can be greatly improved by greatly reducing the residual stress at the welding seam, so that the fatigue resistance of the steel is improved. The method can greatly improve the performance of the steel at the welding position, improve the fatigue resistance and prolong the service life by combining low-temperature heat treatment and wave-band ultrasonic treatment.

Detailed Description

A treatment method for improving stress concentration of a steel structure welding part comprises the following steps:

(1) cleaning, deoiling and drying the steel structural part;

(2) welding and connecting the steel structural members together;

(3) carrying out low-temperature heat treatment on the steel welding seam to obtain a low-temperature heat treatment piece;

(4) and performing wave-section ultrasonic treatment on the welding seam of the low-temperature heat treatment piece.

And the steel structural part is soaked and cleaned by sequentially adopting hot alkaline solution and acetone for cleaning and deoiling.

The hot alkali solution is soaked and cleaned for 20-30min at the temperature of 80-90 ℃;

the hot alkali solution is a sodium hydroxide solution with the mass fraction of 10%.

The acetone soaking and cleaning time is 10-15min, and the temperature is 50-55 ℃.

And the welding is carried out in a plasma arc welding mode.

The plasma arc welding speed is 200-.

The low-temperature heat treatment comprises the following steps: under the protection of inert atmosphere, heating to 445-468 ℃, preserving heat for 2-3 hours, and then cooling to room temperature along with the furnace.

The inert atmosphere is a nitrogen atmosphere.

The wave band type ultrasonic treatment is carried out by three times: the first ultrasonic treatment time is 10-14min, the ultrasonic frequency is 25kHz, the second ultrasonic treatment time is 3-5min, the ultrasonic frequency is 40kHz, the third ultrasonic treatment time is 8-10min, and the ultrasonic frequency is 30 kHz.

The following will clearly and completely describe the technical solutions of the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A treatment method for improving stress concentration of a steel structure welding part comprises the following steps:

(1) cleaning, deoiling and drying the steel structural part; and the steel structural part is soaked and cleaned by sequentially adopting hot alkaline solution and acetone for cleaning and deoiling. The hot alkali solution is soaked and cleaned for 20min at the temperature of 80 ℃; the hot alkali solution is a sodium hydroxide solution with the mass fraction of 10%. The acetone soaking and cleaning time is 10min, and the temperature is 50 ℃.

(2) Welding and connecting the steel structural members together; and the welding is carried out in a plasma arc welding mode. The plasma arc welding speed is 200mm/min, the wire feeding speed is 180mm/min, the ionic gas flow is 2.5L/min, and the welding current is 115A.

(3) Carrying out low-temperature heat treatment on the steel welding seam to obtain a low-temperature heat treatment piece; the low-temperature heat treatment comprises the following steps: heating to 445 ℃ under the protection of inert atmosphere, preserving heat for 2 hours, and then cooling to room temperature along with the furnace. The inert atmosphere is a nitrogen atmosphere.

(4) And performing wave-section ultrasonic treatment on the welding seam of the low-temperature heat treatment piece. The wave band type ultrasonic treatment is carried out by three times: the first ultrasonic treatment time is 10min, the ultrasonic frequency is 25kHz, the second ultrasonic treatment time is 3min, the ultrasonic frequency is 40kHz, the third ultrasonic treatment time is 8min, and the ultrasonic frequency is 30 kHz.

Example 2

A treatment method for improving stress concentration of a steel structure welding part comprises the following steps:

(1) cleaning, deoiling and drying the steel structural part; and the steel structural part is soaked and cleaned by sequentially adopting hot alkaline solution and acetone for cleaning and deoiling. The hot alkali solution is soaked and cleaned for 30min at the temperature of 90 ℃; the hot alkali solution is a sodium hydroxide solution with the mass fraction of 10%. The acetone soaking and cleaning time is 15min, and the temperature is 55 ℃.

(2) Welding and connecting the steel structural members together; and the welding is carried out in a plasma arc welding mode. The plasma arc welding speed is 225mm/min, the wire feeding speed is 190mm/min, the ionic gas flow is 2.8L/min, and the welding current is 118A.

(3) Carrying out low-temperature heat treatment on the steel welding seam to obtain a low-temperature heat treatment piece; the low-temperature heat treatment comprises the following steps: heating to 468 ℃ under the protection of inert atmosphere, preserving heat for 3 hours, and then cooling to room temperature along with the furnace. The inert atmosphere is a nitrogen atmosphere.

(4) And performing wave-section ultrasonic treatment on the welding seam of the low-temperature heat treatment piece. The wave band type ultrasonic treatment is carried out by three times: the first ultrasonic treatment time is 14min, the ultrasonic frequency is 25kHz, the second ultrasonic treatment time is 5min, the ultrasonic frequency is 40kHz, the third ultrasonic treatment time is 10min, and the ultrasonic frequency is 30 kHz.

Example 3

A treatment method for improving stress concentration of a steel structure welding part comprises the following steps:

(1) cleaning, deoiling and drying the steel structural part; and the steel structural part is soaked and cleaned by sequentially adopting hot alkaline solution and acetone for cleaning and deoiling. The hot alkali solution is soaked and cleaned for 25min at the temperature of 87 ℃; the hot alkali solution is a sodium hydroxide solution with the mass fraction of 10%. The acetone soaking and cleaning time is 14min, and the temperature is 52 ℃.

(2) Welding and connecting the steel structural members together; and the welding is carried out in a plasma arc welding mode. The plasma arc welding speed is 212mm/min, the wire feeding speed is 183mm/min, the ionic gas flow is 2.72L/min, and the welding current is 116A.

(3) Carrying out low-temperature heat treatment on the steel welding seam to obtain a low-temperature heat treatment piece; the low-temperature heat treatment comprises the following steps: heating to 451 ℃ under the protection of inert atmosphere, preserving heat for 2.5 hours, and then cooling to room temperature along with the furnace. The inert atmosphere is a nitrogen atmosphere.

(4) And performing wave-section ultrasonic treatment on the welding seam of the low-temperature heat treatment piece. The wave band type ultrasonic treatment is carried out by three times: the first ultrasonic treatment time is 12min, the ultrasonic frequency is 25kHz, the second ultrasonic treatment time is 4min, the ultrasonic frequency is 40kHz, the third ultrasonic treatment time is 9min, and the ultrasonic frequency is 30 kHz.

Test of

Taking Q235 steel as a sample, respectively processing by using comparative example methods of embodiments, after welding, respectively testing the residual stress of the welding seam of the sample along the direction of the vertical welding seam by using an XStress3000X ray stress tester, measuring 5 different points in total, and taking an average value;

TABLE 1

	Residual stress/MPa
		Example 1	-151
Example 2	-150
		Example 3	-153
Comparative example 1	-141
		Comparative example 2	-125
Control group	158

Control group: the difference from the example 3 is that only the step (1) and the step (2) are carried out for treatment;

comparative example 1: the difference from the example 3 is that the low-temperature heat treatment is not carried out;

comparative example 2: the difference from example 3 is that the ultrasonic wave is continuously treated for 25min only by using the frequency of 25 kHz;

as can be seen from Table 1, the residual stress at the weld joint of the steel processed by the method of the invention is greatly reduced, and the problem of stress concentration can be greatly improved by greatly reducing the residual stress at the weld joint, so that the fatigue resistance of the steel is improved.

The fatigue test is carried out at room temperature by adopting a longitudinal tension-compression loading mode of a German SIN-COTEC high-frequency fatigue testing machine, the dynamic load is +/-1.5 kN, the stress cycle curve is a sine line, the frequency is 41.5Hz, the tension-compression load ratio R = -1, and the cycle base number is 10⁷：

The frequency of the alternating load applied to the comparative examples and the comparative samples is greatly changed;

TABLE 2

	Alternating load action/times
		Example 1	2.79×106
Example 2	2.80×106
		Example 3	2.83×106
Comparative example 1	2.42×106
		Comparative example 2	2.14×106
Control group	1.58×104

Control group: the difference from the example 3 is that only the step (1) and the step (2) are carried out for treatment;

comparative example 1: the difference from the example 3 is that the low-temperature heat treatment is not carried out;

comparative example 2: the difference from example 3 is that the ultrasonic wave is continuously treated for 25min only by using the frequency of 25 kHz;

as can be seen from Table 2, the method of the invention can greatly improve the performance of the steel at the welding position, improve the fatigue resistance and prolong the service life.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention, and the present invention is not limited to the illustrated embodiments, and all the modifications and equivalents of the embodiments may be made without departing from the spirit of the present invention.