Titanium is a very active metal. It has a strong affinity with carbon, hydrogen, oxygen and nitrogen at high temperature. It forms brittle compounds such as titanium hydride, titanium carbide, titanium oxide and titanium nitride in the weld to make the weld plastic. The toughness is reduced. Titanium has a small thermal conductivity, a high melting point, and is prone to heat concentration during welding. The high temperature residence time is too long, which leads to coarse grain of the weld and reduces the overall performance of the welded joint. Therefore, the welding of titanium must have good gas protection measures and reasonable welding specifications.
Butt welding process of titanium plate
(1) Processing the groove. With a V-shaped groove, 1 + 0. 50mm blunt edge, groove angle 30 + 2. 52. 5 °. The groove is machined by mechanical methods, and the surface must be free of cracks, delamination, slag inclusions and other defects.
(2) Cleaning. Before welding, clean the wire and the surface of both sides of the groove with acetone at least 50mm, and weld within 2h, otherwise clean again.
(3) The tail mop and the back mop protection are strictly implemented during the welding process.
(4) The welding wire does not swing during the welding process.
(5) Check the surface color of the weld after each layer is welded. If the surface color is unqualified, the solder layer should be removed and re-welded.
The copper tube and the baffle of the protective cover are evenly drilled to allow the gas to flow out evenly. A trailing tug is added to the rear of the torch to enhance front protection, and the back tug is placed on the back of the weld and moves according to the welding speed. The drag mask depends on the shape of the weld. It is necessary to ensure that all the titanium plates in the high temperature zone are placed in the protection, and the shielding gas should be input in advance and the gas can be stopped when the weld is cooled to below 400 °C.