Can titanium tubes be welded? How to weld
Titanium tubes are mainly divided into seamless titanium tubes and welded titanium tubes. In terms of the production of seamless titanium tubes, in recent years, due to the improvement of the rolling mill body and automation level, the specifications of seamless titanium tubes have been further expanded, and the dimensional accuracy and product quality will be further improved, thereby producing more specialty products.
In terms of titanium welded pipes, with the establishment of titanium strip production lines and the improvement of titanium strip production processes, the quality of strip products has steadily improved, resulting in lower production costs and stable prices for titanium welded pipes. Therefore, titanium pipes can be welded, but you need to pay attention to material differences, welding difficulties and welding process requirements.
How to weld titanium pipe
Argon arc arc welding, submerged arc welding and vacuum electron beam welding, etc. If the thickness is less than 3 mm, use TIG welding, and if it is more than 3 mm, use MIG welding. The gas purity is not less than 99.99%, and the air and water vapor content in the argon gas is strictly controlled. Surface treatments such as oil stain removal, oxide scale removal, and oxide film removal are required before welding.
Because titanium and titanium alloys are chemically active and easily contaminated by oxygen, nitrogen, and hydrogen, welding methods such as arc welding, oxyacetylene gas welding, carbon dioxide welding, and atomic hydrogen welding cannot be selected.
What should we pay attention to when welding titanium pipes?
1. Porosity problem during welding
When welding titanium and its alloys, it is common to notice clustered pores around the fusion line after passing through the weld RT. The focus of pores is hydrogen pores, because the solubility of hydrogen in titanium decreases as the temperature increases. The high temperature around the fusion line during welding will cause hydrogen to desolve out. If the hydrogen partial pressure in the atmosphere near the welding zone is high, the hydrogen in the molten metal will not easily precipitate, so hydrogen pores will accumulate.
2. Crack problem during welding
When welding titanium base materials, because the material contains less sulfur and phosphorus impurities, hot cracks are less likely to occur. However, when welding titanium materials, cold cracks are very likely to occur and may cause delays. The key is that titanium has poor thermal conductivity and dissipates heat slowly, which can easily cause the weld to have coarse grains. When the content of gas impurities is high, the plasticity of the welded joint decreases, and hydrogen embrittlement occurs when a large amount of hydrogen is dissolved in the weld.
3. Gas protection during welding
During the titanium welding process, the purity of the gas is very high, so we use high-purity argon. The scope of protection required by argon is the base metal in the molten pool, heat-affected zone and 10 mm area outside the fusion line on both sides. For this purpose, gas protection equipment should be developed, and gas chamber equipment should be used to protect the inside of the pipeline.
Titanium pipes can be welded, but they need to be distinguished according to their material characteristics and process requirements. Therefore, when welding titanium pipes, you need to pay attention to the selection of appropriate welding materials, gas protection, melting point and skills to ensure the quality and stability of the welding.
