There are three main types of cracks during the welding process: crystal cracks, liquation cracks and reheat-like cracks. In the solidification process after laser welding, the weld seam undergoes a temperature zone where the metal has low plasticity, which is brittle temperature zone, and the weld seam metal crystallization is carried out under the action of tensile stress.
This tensile stress is formed because the welded metal is difficult to shrink. The presence of tensile stress causes elastic-plastic deformation of the weld seam. If the welded metal is in the brittle temperature zone, and the plastic deformation exceeds the plasticity of the metal, it will form a crack.
2. The reason why it has pores in the process of welding metal materials:
The air hole is "Scabies" to the laser welding, which seriously affects the strength of the laser welding and also impairs the welding aesthetics. During the laser welding process, the generation of pores is mainly caused by poor protection, nitrogen invades the molten pool from the outside. The solubility of nitrogen in liquid metal is very different from the nitrogen solubility in solid metal, and thus during the cooling and solidification of the metal, since the solubility of nitrogen decreases with the decrease of temperature, when the molten metal cools to the beginning of crystallization, the solubility will suddenly drop sharply. At this time, a large amount of gas is generated to form bubbles. If the floating speed of the bubbles is lower than the metal crystallization rate, pores are formed.
Shenzhen Sunlaser Technology Co., Ltd. is a high-tech company integrating laser equipment research and development, production, sales and service. It has always adhered to the philosophy of “relying on technological innovation and customer service” to eliminate technical problems and provide technology support for customers, ensure the efficiency of equipment and ravel out customer's concerns.
Contact: Yousheng Fang
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