Stainless steel, a new type of material, is widely used in various industries, including aerospace and auto parts, due to its superior corrosion resistance and ability to be molded into various shapes.
Laser welding of stainless steel plays a crucial role, especially in the automotive industry, where the entire body of a vehicle is connected by welding.
However, the welding process can result in significant deformations due to several factors, making control difficult and hampering the sustainable development of related industries.
Consequently, further research into deformation control during laser welding of stainless steel plates is crucial for continued progress in this field.
1. Laser Welding Overview
Laser welding is a process in which a laser beam is used as a heat source to melt and join two workpieces.
During laser welding, laser energy is directed to the surface of the material to be welded. Part of the energy is reflected, while the rest is absorbed by the material, leading to the completion of the welding process.
In essence, the laser welding process involves focusing a high-power laser beam on the surface of the material to be welded, using the material's absorption of light energy to generate heat, and then forming a welding joint after cooling. .
Laser welding can be broadly classified into two categories: thermal conduction welding and deep penetration welding.
2. Damage caused by welding deformation and main factors affecting welding deformation
The main factors that impact welding deformation are welding current, pulse width and frequency.
An increase in welding current results in an increase in weld width and the gradual appearance of spatter, leading to oxidation deformation and roughness on the weld surface.
When the pulse width reaches a certain point, the heat conduction energy consumption of the material surface also increases, causing the liquid to splash out of the molten pool through evaporation. This results in a decrease in the cross-sectional area of the weld joint and affects its strength.
The influence of welding frequency on the deformation of stainless steel sheets is closely related to the thickness of the steel sheet. For example, a 0.5mm stainless steel plate will experience a higher overlap rate when the frequency reaches 2Hz. However, if the frequency reaches 5Hz, the welding seam will be severely burned, leading to a wide zone affected by heat and deformation.
Therefore, it is essential to effectively control welding deformation.
3. Effective measures to prevent laser welding deformation
To reduce deformation during laser welding and improve the welding quality of stainless steel sheets, the following steps can be taken to optimize the welding process parameters:
3.1 Actively introduce orthogonal experimental method
The orthogonal experiment method is a mathematical statistical technique that involves the analysis and organization of multifactorial experiments using an orthogonal table.
This method allows the efficient collection of results through fewer experiments and the identification of the best implementation scheme. It also allows for more in-depth analysis and provides relevant information to support specific work.
Typically, welding current, pulse width, and laser frequency are selected as key variables, with welding deformation serving as the index to be minimized.
It is important to follow the principle of rationality and control factors within a reasonable range. For example, for a 0.5 mm thick stainless steel sheet, the welding current can be controlled between 80 to 96 I/A and the frequency between 2 to 5 f/Hz.
3.2 Orthogonal table selection
In general, the number of levels of experimental factors should correspond to 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 well-designed orthogonal table provides adequate support and guidance for subsequent research.
3.3 Test result range analysis
According to the test results for a 0.5mm thick stainless steel plate, the range of each column was found to be uneven, indicating that different levels of each factor have unique impacts and are not equally influential.
The order of influence on laser welding deformation is current, pulse width and frequency. Based on these factors, the ideal welding process parameters for laser welding should be a current of 85 A, a pulse width of 7 ms, and a frequency of 3 Hz.
To minimize welding deformation of a 0.5 mm thick stainless steel sheet, these parameters must be controlled within these values.
For a 0.8 mm thick stainless steel plate, the current, pulse width and frequency should be controlled at 124 A, 8 ms and 4 Hz respectively to minimize deformation and at the same time meet to the required tensile strength of the weld.
For a 1.6 mm thick stainless steel plate, the parameters must be controlled at 160 A, 11 ms and 5 Hz.
By controlling the parameters within a reasonable range during laser welding, the welding quality and efficiency can be improved while preventing the deformation of the steel plate, thus meeting production demands.
With advances in technology, control of welding deformation has also developed, for example, through the application of finite element simulation. This makes it possible to improve the tension balance in the stainless steel sheet, avoiding welding deformation by controlling the welding temperature and tension.
By preventing deformation, welding quality can be improved, promoting the continuous growth and development of related industries.
4. Conclusion
As an effective welding technology, laser welding has a positive impact on improving welding quality. However, due to the influence of factors such as laser current, laser welding of stainless steel plates may result in deformation and other problems.
To mitigate these problems, welding personnel can use the orthogonal experimental method to determine the best process parameters for different thicknesses of steel sheets and continuously improve the welding quality by combining these parameters with the welding parameters. This can help prevent the occurrence of deformation of the steel plate.
