Application of Tungsten Arc Welding in the Welding of Stainless Steel Sheet
Welding principle
TIG welding is a kind of open arc welding. The arc is stable and the heat is concentrated. Under the maintenance of inert gas (argon), the welding pool is pure and the weld quality is good. However, when welding stainless steel, especially austenitic stainless steel, the reverse side of the weld is also required to stop maintenance, otherwise it will produce severe oxidation, affecting weld formation and welding performance.
Welding characteristics
The welding of stainless steel sheets has the following characteristics:
(1) The stainless steel sheet has poor thermal conductivity and is easily burned directly.
(2) The welding wire is not required for welding, and the base material is directly fused.
Therefore, the quality of stainless steel sheet welding is closely related to the operator, equipment, materials, construction methods, external environment during welding, and testing.
In the welding process of stainless steel sheet, no welding consumables are required, but the following information is requested to be high: First, the purity, flow rate and argon-passing time of argon gas, and second, tungsten electrode.
(1) Argon gas
Argon is an inert gas and is not easy to react with other metal materials and gases. Because of the cooling effect of the airflow, the weld heat affected zone is small and the weldment deformation is small, which is the most ideal maintenance gas for tungsten argon arc welding. The purity of argon must be greater than 99.99%. Argon is mainly effective for stopping the molten pool. During the welding process, the air is prevented from corroding the molten pool and causing oxidation. At the same time, effective air isolation is stopped for the weld area, the weld area is maintained, and the welding performance is improved.
(2) Tungsten
The surface of the tungsten electrode should be lubricated, the end must be sharpened, and the concentricity is good. In this way, the high-frequency arc striking is good, the arc stability is good, the melting is deep, the molten pool can be kept stable, the weld bead is formed well, and the welding quality is good. If the surface of the tungsten electrode is burned out or there are defects such as contaminants, cracks, shrinkage holes, etc., the high-frequency arc striking is difficult during the welding, the arc is unstable, the arc is drifting, the molten pool is dispersed, the appearance is expanded, the penetration is shallow, and the weld is welded. Poor forming and poor welding quality.
Conclusion
1) The stability of tungsten argon arc welding is good, and the shape of different tungsten poles has a great influence on the welding quality of stainless steel sheets.
2) Flat-tipped taper tip tungsten electrode welding can improve the double-sided forming rate of single-sided welding, reduce the heat affected zone of welding, make the weld bead beautiful, and have better comprehensive mechanical properties.
3) Welding defects can be effectively prevented by using the correct welding method.
Oct 29, 2019
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