Stainless steel is a new type of environmentally friendly material. With its characteristics of corrosion resistance and formability, it has been widely used in the field of auto parts.
In the automotive industry, due to the stainless steel raw material (steel plate), the car bodies must all be connected by welding. Therefore, laser welding plays a very important role in the application of stainless steel in the automotive industry.
Due to the influence of many factors, stainless plates welding have deformation problems and is difficult to control, which will greatly affect the application of stainless plates in the automotive industry. So, what is the countermeasure?
Overview of Laser Welding Stainless Plates
Laser welding mainly refers to a welding method that uses laser energy as a heat source to melt and connect workpieces. In the process of laser welding, the laser irradiates the surface of the material to be welded and affects 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 the 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. Finally, the welding joint is formed by cooling. A kind of melting welding process. Under normal circumstances, laser welding is mainly divided into thermal conductivity welding and deep penetration welding.
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, resulting in a smaller cross-sectional area of the solder joint, which 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. It can be seen that it is imperative to strengthen the effective control of welding deformation.
Effective Countermeasures to Avoid Laser Welding Distortion
To reduce the problem of laser welding deformation and improve the welding quality of stainless steel plates, we can start by optimizing welding process parameters. The specific operation methods are as follows:
1. Actively introduce the orthogonal experiment method
The orthogonal experiment 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 best 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 key observation objects, welding deformation is regarded as an index, and it is controlled to the minimum value, 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. A reasonable design of the orthogonal table can provide corresponding support and help for subsequent research work.
3. Analysis of extremely poor test results
Through the test results of the stainless plates 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 impacts are also different. The effects on the laser welding deformation are current, pulse width, and Frequency, comprehensive factors, the best 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 the smallest welding deformation of the 0.5mm stainless steel plates.
For stainless plates with a thickness of 0.8mm, when the deformation is minimized based on meeting the tensile strength of the weld, the parameters such as current, pulse width, and frequency should be controlled at 124A, 8ms, and 4Hz respectively. 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. Welding deformation can also improve welding quality, thereby promoting the healthy development of related fields.
In Conclusion
As an effective welding technology, laser welding technology plays an active role in improving welding quality. However, due to the influence of factors such as laser current, laser welding of stainless plates has problems such as deformation. In this regard, welders can take the orthogonal experiment method to obtain the best process parameters of different thickness steel plates, combine the parameters to perform welding work, and continuously improve the welding quality, to minimize the occurrence of steel plate deformation.