TIG for welding titanium tube(I)

　　Although titanium has a reputation for being difficult to weld, it doesn't have to be problematic. Paying close attention to filler metal selection, cleanness, and use of the shielding gas are three steps to successful GTAW on titanium tube and pipe.Today ,we mainly talk about cleanness and fit-up in welding titanium tube.

　　Cleanness Is Critical

　　Welding titanium tubing requires extreme cleanness—the base metal, filler metal, and welding environment must be immaculate. Contamination by natural body oils, oils from the forming and drawing process, shop dust, paint, dirt, cutting fluids, and lubricants all can lead to embrittlement and weld failure.

　　Start by cleaning the work area and ridding it of any debris, and be certain to choose a place with minimal airflow so as not to disturb the shielding gas during welding. Next degrease both the filler rod and the base metal: Wear nitrile gloves dedicated to this purpose to prevent body oils from rubbing off on these items. Then apply methyl ethyl ketone (MEK) to a clean, lint-free cloth and wipe the titanium to remove any remaining surface contamination. At this point place the filler rod into an airtight container to prevent further contamination.

　　Before welding, remove the oxide scale, which forms when the titanium reacts with oxygen, from the surface of the tubing. This oxide layer provides titanium with its notable corrosion resistance. Still, it must be removed before welding because it melts at a higher temperature than titanium and can enter the molten weld pool to create inclusions that weaken the weld.

　　Either a die grinder with a carbide deburring tool or a carbide file—both dedicated to titanium—works best to remove the oxide layer from the weld joint. Steel wool and abrasives are not recommended because they can cause contamination. Remember to use a low grinding speed to prevent excessive heat. Wipe the joint once more with MEK or acetone-soaked cloth after the oxide layer has been ground away. Wait for the solvent to fully evaporate before striking an arc, because some solvents have low flash points.

　　A Perfect Fit(up)

　　Joint fit-up is arguably more important on titanium tubing than on any other metal tubing because it is critical to prevent oxygen from entering the weld. The joint should be square (do not create a V-notch), which helps minimize the amount of heat and weld metal needed to fill the joint; this in turn lowers the chance of burn-through and contamination.

　　Clamp the pieces into a positioner or on a workstation to make sure the two ends are butted together as tightly and accurately as possible.

　　If you want to know more about welding titanium tube,please concern Baoji Xilitong.