Discussion on the control strategy of steel structure welding deformation and defects

soldereddeformation controlThere are many kinds of methods, which can be applied flexibly for different situations. Because the welding process is complicated and numerous, and the shape of the steel structure varies greatly, therefore, finding effective control methods has always been the key point of research in the field of steel structure welding, so as to achieve the purpose of controlling the welding deformation efficiently, and ultimately provide a strong guarantee for the quality and stability of the steel structure project.

01 Basic theory of welding deformation

Definition of welding distortion and its effects

In the steel structure welding process, due to the local high temperature, material non-homogeneous factors such as the impact to be, the weld seam and the surrounding area will often appear deformation. This deformation not only has an impact on the overall aesthetics of the steel structure, but may also reduce its serviceability. In-depth understanding of the definition of welding deformation and its influencing factors, for the development of effective control measures have important significance.

In the welding, due to high temperature, the welding material will be expanded, but, as the temperature drops, the material will be contracted, this thermal expansion and contraction of the situation will lead to changes in the shape of the material, that is, to produce welding deformation, it should be noted that the deformation produced by continuous unilateral welding is generally greater than the deformation of the two sides of the cross-welding, because the unilateral welding will lead to higher temperatures, which will aggravate the material's In addition, the uneven distribution of welding temperature will further increase the degree of deformation of the weld, which will have a serious impact on the manufacture of finished products.

Main forms of welding deformation

Among the many forms of welding deformation, there are six common basic types, they are shrinkage deformation, and angular deformation, as well as bending deformation, in addition to distortion deformation, and then wave deformation, and finally is the wrong side of the deformation. The causes of these deformations are different, shrinkage deformation mainly from the longitudinal and transverse contraction of the weld; angular deformation is mostly due to the V-bevel butt weld welding seam layout asymmetry. Resulting in uneven contraction of the weld up and down the transverse; bending deformation often occurs in the “T” beam welding, due to the asymmetry of the weld arrangement, so that the weld more than one side of the contraction is larger, which in turn led to workpiece bending; twisting deformation, that is, helical deformation, more often in the I-beam welding, which is usually caused by the welding sequence and direction of the unreasonable Wave deformation is common in thin plate welding, weld contraction resulting in a large local compressive stress and instability of the thin plate, the final component shows a wave; wrong edge deformation often occurs in the welding process of the two plates, due to inconsistent thermal expansion. May cause length or thickness direction of the wrong side.

02 Welding defect generating factors

Influence of welding equipment

There are many factors that can cause defects in the welding process. The performance of the welding equipment and maintenance situation, will have a direct impact on the quality of welding, equipment failure or improper operation, may lead to welding defects. In the welding of steel structure, welding machine is an indispensable equipment. Its performance and welding quality is directly related. Therefore, it is necessary to carry out regular maintenance and inspection of the welding machine to ensure that its functions are in a normal state, and can accurately output parameters such as current, voltage and airflow. However, in practice, we have found that many welding machines are unstable and difficult to meet high welding standards. In addition, during the maintenance period often just do some surface treatment, not in accordance with the professional provisions of the welding machine to operate, which also has an impact on the performance of the show.

Impact of welders

In the process of steel structure welding, the professionalism and skill level of welders are extremely critical. The knowledge level and skills of the welders have an impact on the welding quality, and the lack of skills may cause damage to the welding quality. Welders should not only have the appropriate technical level and qualification certificate, but also have to be proficient in all kinds of welding methods, and to have a wealth of practical experience as well as rigorous and serious attitude to work like however. In the actual operation, we found that some of the welders' skill level does not meet the standard requirements.

Welding processImpact of the level of technology

Welding technology is crucial for the quality of weld seams, and a slight deviation may lead to welding defects. Welding technology plays a key role in steel structure welding, which directly affects the welding quality and results. Therefore, it is necessary to ensure the quality of welding in actual welding work. This requires that the welders have the appropriate level of welding skills and that they operate in strict accordance with the established welding procedures.

03 Welding Deformation Control Strategy

Design phase control strategy

On the welding process of steel structure, plays a key role in the design stage for welding deformation control. In order to effectively reduce the deformation caused by welding, we must carry out a scientific and appropriate structural design of the steel structure. By means of rational design, we can ensure that the number and size of weld seams can be effectively controlled to reduce the risk of welding deformation due to excessive heat input.

Construction Phase Control Strategies

In the steel structure welding process, in order to facilitate the effective control of welding deformation, we have to analyse the node structure and the type of weld thoroughly. During the construction period, the rigid fixation method can be implemented, the assembly welding sequence can be properly arranged, and there are also initiatives such as the anti-deformation method. In addition, the anti-deformation method is an effective preventive method. Before welding, the scale and direction of deformation of the components must be identified in advance, so that after welding to meet the design criteria.

In modern technology, welding is a key link, which is extremely important for the production of products to ensure the significance. However, the deformation produced in the welding process, will directly affect the product's own moulding quality! Therefore, when carrying out product welding operations, we must attach great importance to this issue, and to continue to explore new welding technology, in order to ensure that the welding process has a lasting, and then be able to prevent welding deformation, and ultimately protect product quality.