The Laser welding machine mainly refers to a welding method that uses laser energy as a heat source to melt and connect workpieces. During the laser welding process, the laser irradiates the surface of the material to be welded and has an effect on it. A part of it is reflected and the rest is absorbed into the material to complete the welding target. In short, the process of laser welding is to use a high-power laser beam focused by an optical system to irradiate the surface of the material to be welded, and then make full use of the material to absorb light energy for heating and other treatments, which are cooled to form a welded joint. Kind of melting welding process. Under normal circumstances, laser welding is mainly divided into thermal conductivity welding and deep penetration welding.

As a new type of material, stainless steel has been widely used in aerospace, auto parts, and other fields due to its corrosion resistance and formability. The application of laser welding in stainless steel occupies a very important position, especially in the automotive industry, where all car bodies are connected by welding. However, due to many factors, the welding of stainless steel plates has deformation problems and is difficult to control, which is not conducive to the sustainable development of related fields. Therefore, it is of great significance to strengthen the research on laser welding deformation of stainless steel plates.

1. The hazards of welding deformation and the main factors affecting welding deformation:

The main factors affecting welding deformation are welding current, pulse width, and frequency. As the welding current increases, the width of the weld seam also increases, and phenomena such as splashes gradually appear, resulting in oxidation and deformation of the weld seam surface, accompanied by roughness; the increase in pulse width increases the strength of the welded joint. When the pulse width reaches a certain level, The heat conduction energy consumption on the surface of the material also increases. The evaporation causes the liquid to splash out of the molten pool, which causes the cross-sectional area of the solder joint to become smaller and affects the strength of the joint; the influence of the welding frequency on the welding deformation of the stainless steel plate is closely related to the thickness of the steel plate. For example, for a 0.5mm stainless steel plate, when the frequency reaches 2Hz, the overlap rate of the weld is higher; when the frequency reaches 5Hz, the weld is burned seriously, the heat-affected zone is wider, and deformation occurs. This shows that it is imperative to strengthen the effective control of welding deformation.

2. Effective countermeasures to avoid laser welding deformation:

In order to reduce the problem of laser welding deformation and improve the welding quality of stainless steel plates, we can start with optimizing welding process parameters. The specific operation methods are as follows:

(1) Actively introduce the orthogonal experiment method

The orthogonal experimental method mainly refers to a mathematical-statistical method that analyzes and arranges multi-factor experiments through orthogonal tables. It can use fewer experiments to obtain effective results and infer the implementation plan. At the same time, it can also conduct in-depth analysis, obtain more relevant information, and provide a basis for specific work. Generally, welding current, pulse width, and laser frequency are selected as the inspection objects, welding deformation is regarded as an indicator, and the principle of reasonableness is adhered to, and the factor level is controlled within an appropriate range. For example, for a stainless steel plate with a thickness of 0.5mm, the current can be controlled between 80~96I/A; the frequency is between 2~5f/Hz, etc.

(2) The choice of orthogonal table

Under normal circumstances, the number of test factor levels should be consistent with the number of levels in the orthogonal table, and the number of factors should be less than the number of columns in the orthogonal table.  Reasonable design of the orthogonal table can provide corresponding support and help for subsequent research work.

(3) Extremely poor test results analysis

According to the test results of the stainless steel plate with a thickness of 0.5mm, the range of each column is not equal, which proves that the different levels of each element are unique, and the effects are different. The effects on the laser welding deformation are current, pulse width and Frequency, comprehensive factors, the laser welding process parameters should control the current to 85A, the pulse width is 7ms, and the frequency is 3Hz. Controlling the welding process parameters to three values ​​can ensure that the welding deformation of the 0.5mm stainless steel plate is small.

For stainless steel plates with a thickness of 0.8mm, the current, pulse width and frequency parameters should be controlled at 124A, 8ms, and 4Hz to ensure that the deformation is small on the basis of meeting the tensile strength of the weld. The stainless steel plates with a thickness of 1mm are 160A, 11MS, and 5Hz respectively. In the laser welding process, the welder controls various parameters within a reasonable range, which not only improves the welding quality and efficiency but also avoids the deformation of the steel plate and meets the production requirements. With the rapid development of science and technology, the technology of controlling welding deformation has also developed, such as the application of finite element simulation in welding deformation control, etc., by using welding temperature and stress to avoid welding deformation problems, improve the stress balance of stainless steel plates, and avoid steel plates. While welding deformation, it can also improve welding quality, thereby promoting the healthy development of related fields.

3 Conclusion:

According to the above, the laser welding process, as an effective welding technology, plays an active role in improving the quality of welding. However, due to the influence of factors such as laser current, laser welding of stainless steel plates has problems such as deformation. In this regard, welders can take the orthogonal experiment method to obtain the process parameters of different thickness steel plates, combine the parameters to perform welding work, and continuously improve the welding quality, so as to avoid the occurrence of steel plate deformation.