A method for eliminating residual stress in steel structure welding

Abstract

This invention discloses a method for eliminating residual stress in steel structure welding, comprising the following steps: S1, grinding and cleaning the weld between the first and second steel components; S2, placing the large steel structure in a heating furnace, raising the furnace temperature from room temperature to 610-630°C, holding it at that temperature for 30 minutes, and then transferring the large steel structure to a heating furnace with a furnace temperature between 180-200°C for the first cooling, while keeping the furnace temperature constant during the cooling process. When the temperature of the steel structure drops to the same level as the furnace temperature, the power supply to the heating furnace is cut off, and the second cooling is continued until it drops to room temperature; S3, drilling two rows of first drill holes at both ends of the weld along its length and two rows of second drill holes at both ends of the weld along its width. This method eliminates local stress in the weld and its surroundings, and also prevents invisible and inconspicuous cracks from extending to the surrounding area, greatly reducing the residual welding stress in the entire steel structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of steel structure welding residual stress elimination. More particularly, the present application relates to a steel structure welding residual stress elimination method. BACKGROUND

[0002] Welding is a conventional operation in the application of steel structure, and it is a process that can connect and fix two steel structures. In the actual welding process, due to temperature gradient and uneven stress, combined with unfavorable structural conditions, welding stress almost inevitably exists. The steel structure in the field of building construction is usually thick and has many welds, so more and more serious welding stress problems are inevitably present. If the welding residual stress is not released, it may be too large to produce welding cracks, which will have a very serious adverse effect on the processing quality of the steel structure and its later use.

[0003] Therefore, it is urgent to develop a steel member stress elimination method to overcome the above problems. SUMMARY

[0004] In order to achieve these objects and other advantages of the present application, a preferred embodiment of the present application provides a steel structure welding residual stress elimination method, wherein the large steel structure is welded by a first steel member and a second steel member, and the connection between the two forms a weld. The steel structure welding residual stress elimination method comprises the following steps:

[0005] S1, polishing and cleaning the weld between the first steel member and the second steel member;

[0006] S2, placing the large steel structure in a heating furnace, increasing the temperature in the furnace from room temperature to 610-630 DEG C, and keeping the temperature for 30 minutes. Then, the large steel structure after heating and keeping is transferred to a heating furnace with a temperature of 180-200 DEG C in the furnace, and the first cooling is carried out. During the cooling process, the temperature in the furnace is kept unchanged. When the temperature of the steel structure is reduced to the same as the temperature in the furnace, the power of the heating furnace is cut off, and the second cooling is continued until it is reduced to room temperature.

[0007] S3, drilling two rows of first drill holes at the two ends of the weld along the length direction, and drilling two rows of second drill holes at the two ends of the weld along the width direction.

[0008] According to a preferred embodiment of the present application, the S3 further comprises:

[0009] S4, cutting two rows of spaced grooves along the length direction of the weld to form two rows of grooves, the two rows of grooves are arranged in parallel, and the grooves in the two rows of grooves are arranged staggered.

[0010] According to a preferred embodiment of the present application, the cross section of the groove is V-shaped, the included angle of the groove is 35°, the depth of the groove is kept at 0.8-1.0 cm, and the distance between two adjacent grooves is kept at 30-35 cm.

[0011] According to a preferred embodiment of the present application, the temperature rising and falling processes of S2 are both carried out in an ultrasonic environment.

[0012] According to a preferred embodiment of the present application, in S3, the diameter of the first / second drill hole is controlled at

[0013] 6-8 mm, and the distance between two adjacent second drill holes is kept at 15-20 cm, and the distance between two adjacent first drill holes is kept at 1-2 cm.

[0014] According to a preferred embodiment of the present application, in S2, the falling rate of the first falling is less than the falling rate of the second falling.

[0015] According to a preferred embodiment of the present application, in S2, the falling rate of the first falling is less than the falling rate of the second falling.

[0016] According to a preferred embodiment of the present application, S4 is further followed by:

[0017] S5, using a welding torch to blow fire on the weld surface to heat the metal at the weld to a bright red state, and then using a hammer to knock the metal at the weld, until the metal at the weld is dark red.

[0018] The tip of the hammer is a circular arc, the radius of the circle where the circular arc is located is 12-15 mm, and the angle corresponding to the circular arc is controlled at 30-35°. In the whole knocking process, a protective atmosphere is used, the knocking frequency is controlled at 200-230 times / min, the force of each knock is controlled at 180-200 N, the center of the weld is taken as the first knocking point, and the knocking is gradually performed outward.

[0019] According to a preferred embodiment of the present application, in the knocking process of S5, a clamp is used to clamp the first steel member and the second steel member, respectively.

[0020] According to a preferred embodiment of the present application, in the knocking process of S5, a clamp is used to clamp the first steel member and the second steel member, respectively.

[0021] The present application at least has the following beneficial effects:

[0022] 1. The present application drills two rows of first drill holes at the two ends of the weld along the length direction, and drills two rows of second drill holes at the two ends of the weld along the width direction, which can reduce the possibility of the cracks that are not obvious to the naked eye extending to the two ends along the length direction and the two ends along the width direction, and can release the local stress near the drill holes and reduce the possibility of crack generation; and cutting two rows of interval distributed groove bodies on the weld along the length direction of the weld, using the groove bodies to eliminate the local stress around the weld, especially on the weld, the drill holes and the groove bodies act simultaneously, which can eliminate the local stress around the weld and avoid the invisible cracks extending to the surrounding.

[0023] 2. The present application first heats the large steel structure to 610-630 DEG C in the heating furnace, then performs the first cooling in the heating furnace at 180-200 DEG C, and finally performs the second cooling by powering off the heating furnace, the two times of temperature maintaining and cooling can well utilize the stress caused by the plastic deformation of the weld during the temperature maintaining and cooling process to rearrange, so as to reduce the residual stress, and can also reduce the temperature difference between the steel structure body and the weld, thereby reducing the internal stress caused by the temperature difference.

[0024] 3. The present application uses the arc-shaped hammer tip of the special-shaped knocking hammer to continuously knock the weld between the first steel structure and the second steel structure, in the process of knocking, the metal at the weld will be gradually thinned by beating and gradually elongated to the surrounding, in the process of gradually elongating, the weld will gradually shrink, so that the welding residual stress gradually becomes smaller.

[0025] Other advantages, objects, and features of the present application will be apparent to those skilled in the art from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a distribution diagram of the first drill hole, the second drill hole and the groove body in the weld. DETAILED DESCRIPTION

[0027] The present application will be further described below in conjunction with the drawings, so that those skilled in the art can implement the present application according to the description.

[0028] The following description is used to disclose the present application so that those skilled in the art can implement the present application. The preferred embodiments in the following description are only as examples, and other obvious modifications can be thought by those skilled in the art. The basic principles of the present application defined in the following description can be applied to other embodiments, modifications, improvements, equivalents and other technical solutions without departing from the spirit and scope of the present application.

[0029] It can be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of one element can be one, and in another embodiment, the number of the element can be multiple, and the term "one" cannot be understood as a limitation on the number.

[0030] A preferred embodiment of the present application provides a steel structure welding residual stress elimination method, wherein the large steel structure is welded by a first steel member and a second steel member, and the connection of the two forms a weld.

[0031] Embodiment 1

[0032] The steel structure welding residual stress elimination method comprises the following steps:

[0033] S1, polishing and cleaning treatment is performed on the weld between the first steel member and the second steel member;

[0034] S2, the large steel structure is placed in a heating furnace, the temperature in the furnace is increased from room temperature to 630 DEG C, and the temperature is kept for 30 minutes, and the large steel structure after heating and keeping is transferred to a heating furnace with a furnace temperature of 200 DEG C, and the first cooling is carried out, and the furnace temperature is kept unchanged during the cooling process, when the temperature of the steel structure is reduced to the same as the furnace temperature, the power of the heating furnace is cut off, and the second cooling is continued until it is reduced to room temperature; the heating and cooling process of S2 is carried out in an ultrasonic wave environment with a frequency of 20 MHz.

[0035] S3, two rows of first drill holes P1 are drilled at the two ends of the weld along the length direction, and two rows of second drill holes P2 are drilled at the two ends of the weld along the width direction

[0036] of the weld. The diameter of the first drill hole P1 / second drill hole P2 is controlled to be 8 mm, and the distance between adjacent two second drill holes P2 is kept to be 20 cm, and the distance between adjacent two first drill holes P1 is kept to be 1 cm.

[0037] S4, two rows of interval distributed groove bodies P3 are cut on the weld along the length direction of the weld, the two rows of groove bodies P3 are arranged in parallel, and the groove bodies in the two rows are staggered. The cross section of the groove body is V-shaped, the included angle of the groove body is 35 DEG, the depth of the groove body is kept to be 1.0 cm, and the distance between adjacent two groove bodies is kept to be 35 cm.

[0038] S5, the weld surface is heated by using a welding gun, when the metal at the weld is turned into bright red state, knocking is performed on the weld surface by using a hammer, and the knocking is performed along the length direction of the weld.

[0039] The hammer is used to knock the metal at the welding seam, and the knocking is continued until the metal at the welding seam is dark red. The hammer tip of the hammer is an arc, the radius of the circle where the arc is located is 15 mm, and the angle corresponding to the arc is controlled to be between 35°. In the whole knocking process, a protective atmosphere is used, the frequency of the knocking is controlled to be 230 times / min, the strength of each knocking is controlled to be 200 N, and the center of the welding seam is taken as the first knocking point and the knocking is gradually performed outward. In the knocking process of S5, the first steel member and the second steel member are clamped by the clamps respectively.

[0040] It is detected that the welding stress at the welding seam of the large steel structure treated by the method of Example 1 is reduced from 208.5 MPa to 48.9 MPa.

[0041] Example 2

[0042] The difference from Example 1 is that, in S5, the radius of the circle where the arc of the hammer tip of the hammer is located is 25 mm, and the angle corresponding to the arc is controlled to be 20°.

[0043] It is detected that the welding stress at the welding seam of the large steel structure treated by the method of Example 2 is reduced from 208.5 MPa to 76.5 MPa.

[0044] Example 3

[0045] The difference from Example 1 is that, in S5, the radius of the circle where the arc of the hammer tip of the hammer is located is 8 mm, and the angle corresponding to the arc is controlled to be 20°.

[0046] It is detected that the welding stress at the welding seam of the large steel structure treated by the method of Example 3 is reduced from 208.5 MPa to 94.7 MPa.

[0047] Compared with Example 2 and Example 3, it can be seen that, compared with Example 2 and Example 3, the welding stress of Example 1 is reduced more, which indicates that only the hammer with the arc-shaped hammer tip in the protection scope of the present application is used for continuous knocking, the welding residual stress can be reduced to the greatest extent, and the welding residual stress reducing capability of the hammer with the shape outside the protection scope of the present application is reduced.

[0048] Example 4

[0049] The difference from Example 1 is that the step of S2 is different. Specifically, in S2, the large steel structure is placed in a heating furnace, the temperature in the furnace is increased from room temperature to 630℃, and the temperature is kept for 30 minutes. The power supply of the heating furnace is cut off, and the temperature is reduced until it is reduced to room temperature. The temperature increasing and temperature reducing processes of S2 are both performed in an ultrasonic wave environment with a frequency of 20 MHz.

[0050] It is detected that the welding stress of the welds of the large steel structure treated by the method of Example 4 is reduced from 208.5 MPa to 112.3 MPa.

[0051] Comparing Example 1 and Example 4, it can be seen that the welding stress of Example 1 is reduced more than that of Example 4, because the two times of holding and cooling can well utilize the stress rearrangement caused by the plastic deformation of the welds during the holding and cooling process, so as to achieve the purpose of better reducing the residual stress, and can also reduce the temperature difference between the steel structure body and the welds, thereby reducing the internal stress caused by the temperature difference.

[0052] Example 5

[0053] The difference from Example 1 is that only two rows of first drill holes are drilled in S3, and no two rows of second drill holes are drilled, and two rows of groove bodies P3 are cut in S4.

[0054] It is detected that the welding stress of the welds of the large steel structure treated by the method of Example 5 is reduced from 208.5 MPa to 118.8 MPa.

[0055] Example 6

[0056] The difference from Example 1 is that only two rows of second drill holes are drilled in S3, and no two rows of first drill holes are drilled, and two rows of groove bodies P3 are cut in S4.

[0057] It is detected that the welding stress of the welds of the large steel structure treated by the method of Example 7 is reduced from 208.5 MPa to 91.4 MPa.

[0058] Example 7

[0059] The difference from Example 1 is that S3 is cancelled, that is, no two rows of second drill holes are drilled and no two rows of first drill holes are drilled, but two rows of groove bodies P3 are cut in S4.

[0060] It is detected that the welding stress of the welds of the large steel structure treated by the method of Example 7 is reduced from 208.5 MPa to 131.6 MPa.

[0061] Comparing Example 1 and Example 5, Example 6 and Example 7, it can be seen that the welding stress of Example 1 is reduced more than that of Example 5, Example 6 and Example 7, which shows that only the first drill hole in the longitudinal direction, the second drill hole in the transverse direction and the groove body can be used to eliminate the local residual stress of the welds and the surrounding thereof to the greatest extent.

[0062] In summary, it can be seen that the welding stress of Example 1 treated by the method of the application has the best reduction effect.

[0063] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method of eliminating welding residual stress of a steel structure, wherein, The steel structure is welded by a first steel component and a second steel component, and a welding seam is formed at the joint of the two components, characterized in that the steel structure welding residual stress elimination method comprises the following steps: S1, polishing and cleaning the welding seam between the first steel component and the second steel component; S2, placing the steel structure in a heating furnace, increasing the temperature in the furnace from room temperature to 610-630 DEG C, maintaining for 30 minutes, and transferring the steel structure after heating and maintaining to a heating furnace with a furnace temperature of 180-200 DEG C, for the first time to cool, and keeping the furnace temperature unchanged during the cooling process, when the temperature of the steel structure is reduced to the same as the furnace temperature, the power of the heating furnace is cut off, and the second cooling is continued until it is reduced to room temperature; S3, drilling two rows of first holes at the two ends of the welding seam along the length direction, and drilling two rows of second holes at the two ends of the welding seam along the width direction; the diameter of the first / second hole is controlled at 6-8 mm, and the distance between adjacent two first holes is kept at 1-2 cm, and the distance between adjacent two second holes is kept at 15-20 cm; S4, cutting two rows of interval distributed groove bodies along the length direction of the welding seam, the two rows of groove bodies are arranged in parallel, and the groove bodies in the two rows are staggered; the cross section of the groove body is V-shaped, the included angle of the groove body is 35 DEG, the depth of the groove body is kept at 0.8-1.0 cm, and the distance between adjacent two groove bodies is kept at 30-35 cm; S5, using a welding gun to heat the surface of the welding seam, when the metal at the welding seam becomes bright red, using a knocking hammer to knock the metal at the welding seam, and the metal at the welding seam is dark red, the tip of the knocking hammer is a circular arc, the radius of the circle where the circular arc is located is 12-15 mm, and the corresponding angle of the circular arc is controlled at 30-35 DEG, wherein the whole knocking process is carried out in a protective atmosphere, the knocking frequency is controlled at 200-230 times / min, the force of each knocking is controlled at 180-200 N, the center of the welding seam is the first knocking point, and the knocking is gradually outward.

2. The method of claim 1, wherein the method is characterized by: The temperature rising and falling processes of S2 are carried out in an ultrasonic environment.

3. The method of claim 1, wherein the method further comprises: In S2, the first cooling rate is less than the second cooling rate.

4. The method of claim 1, wherein the method further comprises, In the knocking process of S5, a clamp is used to clamp the first steel component and the second steel component respectively.

Images