Attention To High Frequency Induction Welding Of Aluminum Tube And Stainless Steel Pipe

Attention to high frequency induction welding of aluminum tube and stainless steel pipe aluminum tube and stainless steel tube high-frequency Induction Welding difficulties are more, summed up mainly in the following aspects: physical properties, different materials molding process characteristics, equipment and mold processing accuracy, high-frequency welding machine and unit operation control accuracy.

　　Specifically:

　　1, aluminum tube and stainless steel tube physical properties

　　The biggest problem with high frequency induction welding of aluminum tubes and stainless steel tubes is the effect of oxides.

　　1 aluminum is easily oxidized to Al2O3, melting point of up to 2050 ℃, and the melting point of pure aluminum is 658 ℃, welding, the oxide film hinders the melting of the base metal fusion, easy to appear without penetration defects.

　　2) similar to aluminum, when stainless steel W (Cr) >12%, chromium than iron priority and oxidation in the base material surface formation of a dense layer of oxide film Cr2O3, melting point up to 2,265 ℃, and the melting point of chromium is 1857 ℃, will appear similar problems.

　　2, different materials of the molding process characteristics

　　1 The linear expansion coefficient and crystallization shrinkage ratio of aluminum is twice times larger than that of steel, which is easy to produce large welding deformation and internal stress.

　　2 The linear expansion coefficient of stainless steel is larger than that of carbon steel, for example, the expansion coefficient of austenitic stainless steel line is 40% larger than that of carbon steel.

　　3 The austenite stainless steel should be treated with solid solution before forming, in order to reduce the hardness and reduce the deformation resistance, the forming should adopt comprehensive bending deformation.

　　3, equipment and mold processing accuracy Unlike welded carbon steels, the units and molds for welded aluminum and stainless steel tubes require very high machining accuracy, with only minimal axial and radial runout in the licensed operation. Large periodic vibrations can lead to weld defects.

　　General requirements of the machining accuracy of radial runout control in the 0.01-0.03mm range.

　　4, High frequency welding machine and unit operation control accuracy Because of the small plastic range of aluminum alloy and stainless steel material, it is necessary to control the input heat precisely when welding. Any large power fluctuation may result in weld slag and gas hole production. The output of the power supply is generally required to fluctuate below 1%.